Date   

Skies of Hawaii

Roland Christen
 

My wife and I spent a week on the north part of the Big Island of Hawaii, in the Kohala mountain region. The skies there are incredibly dark and transparent with almost no light pollution straight up and just a small amount 35 miles to the south in Kona. In fact we measured the light pollution level to be mag 21.36, which is almost identical to what it is on Mauna Kea on the 9000 foot level.
 
So here is a Milky Way shot, a single 30 second exposure taken with my Sony NEX-7 camera with wide field lens set to 18mm at F4. The camera was attached to my little Vixen Polarie sidereal tracker with only perfunctory polar alignment.
 
 
While we were there, our friend and local astronomy nut, Chris Erickson, let me use his 130EDF refractor, set on his 900 mount to do a little higher resolution shots of some Milky Way objects. I have always enjoyed scanning the southern part of the Milky way with binoculars and two of my favorite bino object were M6 and M7. To me M6 looks like a butterfly in a 10x50 bino, so I tried to capture this effect in the image. M7 is right in the thick of the Milky Way, so this was processed to show the structure of our galaxy with M7 somewhat overexposed. Both of these images are single 10 minute RGB exposures with my QSI 683 camera, guided with the little Lodestar camera, processed in MaximDL. M7 unfortunately had to be severely compressed and made quite small to fit within the 500k limit of Astromart ( I will post a larger version on the Yahoo group files).
 
M6:
 
M7:
 
Marj noticed the dark nebula on the upper left side that she said resembled a finisher or the winner of the Iron Man Marathon which is held on this island this month. You can see his legs running and his arms up in triumph. What do you all think?
 
 
Rolando


Bubble nebula

Roland Christen
 

Hi All,
 
I just posted an image in the photos section of one of the last objects that I photographed with the 12" F8 Mak-Cass astrograph before sending it off to its final location in Chile. The night before we had to pack for our Hawaii trip, the sky at our AP observatory was steady and somewhat clear for about 2 hours before heavy fog settled in and put an end to my testing adventure. The object is the Bubble Nebula, taken with 3 narrow band filters thru haze that was quite thick, so the image is not deep. Nevertheless I did get a nice clear sharp amount of detail in the core of the Bubble. Cannot wait to see how it performs in the basolutely transparent steady skies of Chile, high in the mountains at Las Campanas. It will be installed by December of this year after testing of the rest of the setup out west.
 
This image is in the Photos section of the AP user group. It is a center crop of the much larger 16803 frame. Be sure to click on the largest (original) image:
 
 
Rolando


Re: Meridian Flip - Flop & Flexure compensation factor

Roland Christen
 

Remember that 1 degree of orthogonal error in the scope produces two degrees of error on the sky. Example: if the mount is pointing dead straight up and the scope is pointing 1 degree to the east due to mechanical orthogonal error, when the mount flips sides, it will point dead straight up, but now the scope will point 1 degree due west. Total pointing error is 2 degrees (twice the scope mechanical offset).
 
Rolando


-----Original Message-----
From: Richard Moore
To: ap-gto Sent: Thu, Sep 5, 2013 1:47 am
Subject: Re: [ap-gto] Meridian Flip - Flop & Flexure compensation factor

Hi Joe,

If you decide to use a shim to solve your non-orthogonality, here is the
trigonometric formula for the thickness of the shim:

(thickness of the shim)  equals  (distance between fore and aft connection to
the male D plate)  times
   ( cosine( arc seconds that the target moves after the meridian flip ))

The scientific calculator on my computer required me to convert the arc seconds
to arc degrees by dividing by 3600.

I then went to the hardware store with my micrometer and measured their brass
sheet stock until I found the right combination.

Sketch the geometry of the scope and camera on both sides of the meridian to
find whether to shim fore or aft, (or just trial and error),

Good Luck

Richard


----- Original Message -----
From: Joseph Zeglinski
To: ap-gto@...
Sent: 9/4/2013 18:03:29
Subject: Re: [ap-gto] Meridian Flip - Flop & Flexure compensation factor



Thanks for the confirmation, Rolando.

    Spent all last night using Pempro-2 to adjust the alignment, but as it
turned out -  much to my regret - there wasn’t much to tweak to what I had done
initially with my original manual drift alignment. The alignment seemed to be
pretty decent already. Sky testing clouded out tonight, to see if it made any
difference, or if the target comes closer to FOV on both sides of the pier.

    As for shimming, I am a little dubious about trying to slip a thin piece of
copper under that hefty 75 lb scope. Not much room under the D-plate, or even
knowing which end – fore or aft. Are there procedures to determine which way the
OTA is tilted in its saddle, and roughly how thick a shim might be needed, and
where to place the brass shim? Sure would be a neat feature to add to Pempro, or
any other alignment software

    The software modeling approach might be the easiest.

Joe

From: chris1011@...
Sent: Wednesday, September 04, 2013 3:36 PM
To: ap-gto@...
Subject: Re: [ap-gto] Meridian Flip - Flop & Flexure compensation factor




What you have is classic non-orthogonality. The scope optics point slightly
different direction from the scope mechanical axis. Although it always looks
like a mount problem, it is really simply an inherent offset in the scope
itself. You can try shimming the mounting plate, or you can use one of the
software programs to compensate for this offset.

Rolando




[Non-text portions of this message have been removed]



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Re: Frustrating guiding problem

Roland Christen
 

Hi Peter,
 
Thank you for posting this. It is part of the adjustments that can be made to clear up any Dec guiding issues.
 
Rolando


-----Original Message-----
From: topboxman2000
To: ap-gto
Sent: Wed, Sep 4, 2013 3:20 pm
Subject: [ap-gto] Re: Frustrating guiding problem



Hi Leonardo,

I am not sure what else to say. Take a look at this to see if that's what you
are seeing:

http://www.astro-physics.com/tech_support/mounts/backlash2.pdf

Peter

--- In ap-gto@..., Leonardo Priami  wrote:
>
> Hi Peter,
> thanks for your help.
> About your suggestion:
> - I see (below the PHD screen) that the bigger correction are around
> 150/300 ms, but only when after a few attempt the mount still remain out.
>
> - About the exposure time I set to 3 or 4 seconds. I agree. But still I
> see some jumps as you can see in the pictures I show.
>
> - I can't use the OAG in the main scope because I have only 4 mm from
> the 3"Wynne corrector and the filter wheel flange.
>
> - The FSQ is piggybacked but with very strong system. I would exclude
> flexure.
>
> What I suspect is some "elasticity" somewhere in the gear train that
> bring the motor to rotate a bit and no rotation to the worm gear.
> I think that may occur some stick-slip phenomena between the worm gear
> and the wheel. After have  accumulated sufficient force, than the
> movement will take place, realizing too much movement than requested and
> not when requested.
>
> What do you think about?
>
> Thanks,
>
> Leonardo
>
>
> Il 04/09/2013 17.13, topboxman2000 ha scritto:
> >
> >
> >
> > Hi Leonardo,
> >
> > Your Max Dec Duration of 600msec may be a little too high. Check the
> > log if Dec correction ever hit 600msec. A-P mounts are too smooth and
> > normally have very little to no backlash so Max Dec Duration should
> > not have to be this high. If the seeing is not good and setting Max
> > Dec Duration a little high could cause overshooting. Try set it to as
> > low as 75msec.
> >
> > Also the Min Motion might be a little too small. Small Min Motion can
> > send too many corrections to the mount.
> >
> > Because your mount is high end, I would set the guide exposure times
> > to at least 3 seconds to balance out the seeing and improve guide star
> > image (higher SNR).
> >
> > Can you use OAG for your bigger scope? You can get differential
> > flexure between guide and main scope. You said the guide scope is in
> > parallel with main scope, do you mean side by side or piggyback?
> >
> > Peter
> >
> > --- In ap-gto@..., Leonardo Priami  wrote:
> > >
> > > Sorry, here the link to see the screen shots:
> > >
> > > http://www.lpriami.altervista.org/ImAstro/Service.html
> > >
> > > Thanks for help!
> > >
> > > Leonardo
> > >
> > > Il 04/09/2013 11.37, Leonardo Priami ha scritto:
> > > >
> > > > Hi,
> > > > sorry to being here only when I'm frustrated about something.
> > > >
> > > > Here about the guiding of my AP1200 CP2.
> > > > The handpad has the 4.17 v firmware and the last V2 driver.
> > > >
> > > > - I have a Newton-Wynne 300 mm f/3,8 (1140 mm of focal length) with an
> > > > Apogee U16M and in parallel a FSQ106 (530 mm) with a Apogee F9 (both
> > > > camera with 9 micron pixel).
> > > > - On the main telescope I have a FWHM star about 1,3/1,5 pixel
> > (2,1/2,5
> > > > "), On the FSQ I have a FWHM about 1 pixel.
> > > > - The guiding is performed by a Starlight Lodestar using a MMoag
> > > > off-axis on the FSQ. (3,3/3,4 "/pixel).
> > > > With this parameters I see that I need to perform a guiding with a P-V
> > > > error less than 0,5 pixel (+/- 0,25 pixel). If I found oval stars when
> > > > the error goes to 0,5 pixel.
> > > > - The cable connects directly the Lodestar with the mount.
> > > > - The Lodestar doesn't work under MaximDL, neither with its driver,
> > > > neither with its Ascom driver (it perform a too short calibration even
> > > > if I set 40 sec on setting...)
> > > > -The guiding is performed with PHD
> > > > -The DEC balancing is perfect (may be necessary a little
> > un-balancing?)
> > > > -Polar alignment is very good (I have a Dec Drift of about 1 pixel on
> > > > guider after 10/15 min)
> > > > -I tried more time to adjust the Dec backlash as suggested on the AP
> > > > site. The Dec warm gear shaft can be turn by hand from the gear side
> > > > (dismounting the first gear).
> > > > - Moving manually the gears I see a back-lash of about 1 tooth on the
> > > > first motor gear, moving with handpad I see about of less than 1
> > sec at
> > > > 0,5X to compensate a "1 tooth" backlash (so about 7 arcsec to set
> > the V2
> > > > driver?)
> > > > -I tried with 0,5X and 0,25X without improvement
> > > > -I tried 2s, 3s, and 4 sec, the seeing is 2,3" FWHM, with 4 s I see
> > > > better results, but still I have some Dec jumps
> > > >
> > > > Principally I tried to set "Auto" on the Dec guide setting on PHD,
> > but I
> > > > see a lot of jumps.
> > > > Selecting only one direction the performance is better, but I see some
> > > > jumps every 2-3 min. Also RA seems some times to be correlated.
> > > > I attached three shot that show the graphs. The red line is the Dec.
> > > > Some suggestion to solve?
> > > > Thanks a lot!
> > > >
> > > > Regards,
> > > >
> > > > Leonardo Priami
> > > >
> > > > [Non-text portions of this message have been removed]
> > > >
> > > >
> > >
> >
> >
>




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Re: Frustrating guiding problem

Roland Christen
 

There are several things that you can check and tighten up on the Dec gearbox. First make sure that the spur gear on the end of the worm shaft is tight and this requires that the setscrew is tight on the flat part of the worm shaft. Remove the gearbox cover plate to get to the spur geartrain. If the setscrew is even small amount loose, it will definitely cause your problem.
 
Second, and quite important if the above did not solve the problem, is the end load bearings which hold the worm gear in place. There is a threaded washer at the end of the worm gear which can be tightened so that the worm is held more firmly in place. To do this requires that you remove the gearbox cover plate, then remove the two spur gears ( the large one and then the one which is attached to the end of the worm). Then with a spanner wrench, or two small pins (ends of small diameter drill bits work great for this), you can tighten this threaded washer. Check afterwards that the worm still turns easily by placing the spur gear back on and turning it with your fingers. It should turn smoothly with only small amount of lumpy feel.
Lastly, there are two setscrews on the inside of the gearbox which press against the two end load bearings. To access these, you will need to remove the entire gearbox from the mount and look for these setscrews. If they are loose, the bearings can move sideways, which will not only produce this delay effect during Dec guiding, but will also produce a very small but noticeable RA motion to the telescope. These two setscrews should be hand tightened, but be careful to not tighten so much that it impact the smoothness of the bearings. You can feel this by turning the gears by hand. You will notice a definite lumpy feel when these are too tight.
 
Once all three of the above are adjusted, your mount will guide very smoothly and accurately in Dec. If you have any problem understanding what I have written, then please contact George at AP, and he can talk you thru these adjustments ( I am in Hawaii on vacation right now, but I did forward this to him, so he is aware of your problem).
 
It may also help to put some fresh light lithium grease on the Dec worm and run it back and forth a few times at 1200x. Less friction in Dec means easier reversals.
 
Rolando ( on Kauai at the moment)

-----Original Message-----
From: Leonardo Priami
To: ap-gto <ap-gto@...>
Sent: Wed, Sep 4, 2013 3:04 pm
Subject: Re: [ap-gto] Re: Frustrating guiding problem



Hi Peter,
thanks for your help.
About your suggestion:
- I see (below the PHD screen) that the bigger correction are around 150/300 ms, but only when after a few attempt the mount still remain out.

- About the exposure time I set to 3 or 4 seconds. I agree. But still I see some jumps as you can see in the pictures I show.

- I can't use the OAG in the main scope because I have only 4 mm from the 3"Wynne corrector and the filter wheel flange.

- The FSQ is piggybacked but with very strong system. I would exclude flexure.

What I suspect is some "elasticity" somewhere in the gear train that bring the motor to rotate a bit and no rotation to the worm gear.
I think that may occur some stick-slip phenomena between the worm gear and the wheel. After have  accumulated sufficient force, than the movement will take place, realizing too much movement than requested and not when requested.

What do you think about?

Thanks,

Leonardo


Il 04/09/2013 17.13, topboxman2000 ha scritto:
 


Hi Leonardo,

Your Max Dec Duration of 600msec may be a little too high. Check the log if Dec correction ever hit 600msec. A-P mounts are too smooth and normally have very little to no backlash so Max Dec Duration should not have to be this high. If the seeing is not good and setting Max Dec Duration a little high could cause overshooting. Try set it to as low as 75msec.

Also the Min Motion might be a little too small. Small Min Motion can send too many corrections to the mount.

Because your mount is high end, I would set the guide exposure times to at least 3 seconds to balance out the seeing and improve guide star image (higher SNR).

Can you use OAG for your bigger scope? You can get differential flexure between guide and main scope. You said the guide scope is in parallel with main scope, do you mean side by side or piggyback?

Peter

--- In ap-gto@..., Leonardo Priami wrote:
>
> Sorry, here the link to see the screen shots:
>
> http://www.lpriami.altervista.org/ImAstro/Service.html
>
> Thanks for help!
>
> Leonardo
>
> Il 04/09/2013 11.37, Leonardo Priami ha scritto:
> >
> > Hi,
> > sorry to being here only when I'm frustrated about something.
> >
> > Here about the guiding of my AP1200 CP2.
> > The handpad has the 4.17 v firmware and the last V2 driver.
> >
> > - I have a Newton-Wynne 300 mm f/3,8 (1140 mm of focal length) with an
> > Apogee U16M and in parallel a FSQ106 (530 mm) with a Apogee F9 (both
> > camera with 9 micron pixel).
> > - On the main telescope I have a FWHM star about 1,3/1,5 pixel (2,1/2,5
> > "), On the FSQ I have a FWHM about 1 pixel.
> > - The guiding is performed by a Starlight Lodestar using a MMoag
> > off-axis on the FSQ. (3,3/3,4 "/pixel).
> > With this parameters I see that I need to perform a guiding with a P-V
> > error less than 0,5 pixel (+/- 0,25 pixel). If I found oval stars when
> > the error goes to 0,5 pixel.
> > - The cable connects directly the Lodestar with the mount.
> > - The Lodestar doesn't work under MaximDL, neither with its driver,
> > neither with its Ascom driver (it perform a too short calibration even
> > if I set 40 sec on setting...)
> > -The guiding is performed with PHD
> > -The DEC balancing is perfect (may be necessary a little un-balancing?)
> > -Polar alignment is very good (I have a Dec Drift of about 1 pixel on
> > guider after 10/15 min)
> > -I tried more time to adjust the Dec backlash as suggested on the AP
> > site. The Dec warm gear shaft can be turn by hand from the gear side
> > (dismounting the first gear).
> > - Moving manually the gears I see a back-lash of about 1 tooth on the
> > first motor gear, moving with handpad I see about of less than 1 sec at
> > 0,5X to compensate a "1 tooth" backlash (so about 7 arcsec to set the V2
> > driver?)
> > -I tried with 0,5X and 0,25X without improvement
> > -I tried 2s, 3s, and 4 sec, the seeing is 2,3" FWHM, with 4 s I see
> > better results, but still I have some Dec jumps
> >
> > Principally I tried to set "Auto" on the Dec guide setting on PHD, but I
> > see a lot of jumps.
> > Selecting only one direction the performance is better, but I see some
> > jumps every 2-3 min. Also RA seems some times to be correlated.
> > I attached three shot that show the graphs. The red line is the Dec.
> > Some suggestion to solve?
> > Thanks a lot!
> >
> > Regards,
> >
> > Leonardo Priami
> >
> > [Non-text portions of this message have been removed]
> >
> >
>





Re: Meridian Flip - Flop & Flexure compensation factor

Richard Moore
 

Hi Joe,

If you decide to use a shim to solve your non-orthogonality, here is the trigonometric formula for the thickness of the shim:

(thickness of the shim) equals (distance between fore and aft connection to the male D plate) times
( cosine( arc seconds that the target moves after the meridian flip ))

The scientific calculator on my computer required me to convert the arc seconds to arc degrees by dividing by 3600.

I then went to the hardware store with my micrometer and measured their brass sheet stock until I found the right combination.

Sketch the geometry of the scope and camera on both sides of the meridian to find whether to shim fore or aft, (or just trial and error),

Good Luck

Richard

----- Original Message -----
From: Joseph Zeglinski
To: ap-gto@...
Sent: 9/4/2013 18:03:29
Subject: Re: [ap-gto] Meridian Flip - Flop & Flexure compensation factor



Thanks for the confirmation, Rolando.

Spent all last night using Pempro-2 to adjust the alignment, but as it turned out - much to my regret - there wasn’t much to tweak to what I had done initially with my original manual drift alignment. The alignment seemed to be pretty decent already. Sky testing clouded out tonight, to see if it made any difference, or if the target comes closer to FOV on both sides of the pier.

As for shimming, I am a little dubious about trying to slip a thin piece of copper under that hefty 75 lb scope. Not much room under the D-plate, or even knowing which end – fore or aft. Are there procedures to determine which way the OTA is tilted in its saddle, and roughly how thick a shim might be needed, and where to place the brass shim? Sure would be a neat feature to add to Pempro, or any other alignment software

The software modeling approach might be the easiest.

Joe

From: chris1011@...
Sent: Wednesday, September 04, 2013 3:36 PM
To: ap-gto@...
Subject: Re: [ap-gto] Meridian Flip - Flop & Flexure compensation factor




What you have is classic non-orthogonality. The scope optics point slightly different direction from the scope mechanical axis. Although it always looks like a mount problem, it is really simply an inherent offset in the scope itself. You can try shimming the mounting plate, or you can use one of the software programs to compensate for this offset.

Rolando




[Non-text portions of this message have been removed]


Re: Frustrating guiding problem

Leonardo Priami
 

Hi!
My actually version is 5.01, I will try with 5.10. It will be better use the standard driver or the Ascom driver.
My doubt is also that with CP2 I can not send multiple correction (AR and DEC) at the same time using camera relay (cable connected between Lodestar and the mount). May it be a problem?

Thanks,

Leonardo


Il 05/09/2013 01.11, CurtisC ha scritto:
 

> - The Lodestar doesn't work under MaximDL

There was a version of MaxIm that didn't work with Lodestar. Be sure you have the latest version of MaxIm. Of course, be sure you also have the latest driver for the Lodestar. But the Lodestar driver probably isn't your problem. As for PHD, I couldn't get it to work at all. Stick with MaxIm.



Re: Counterweight Shaft Extension???

Armand P
 

Hi Mark,

I use a counterweight shaft extension to reduce the number of weights to lug around. I've had success with it for imaging. There should be no issues about the shaft flexing or creating any other problems, like demanding more torque from the motors. The shaft is very rigid and good balancing will ensure smooth operation. Given the material the shaft is made of, and if you think of the shaft as a cantilever with a load on it (the weights), there's no way you should get any flexing/deflection. And with your axes balanced well, the motors won't even know there is any equipment mounted. For example, the 74" telescope at my local observatory (which is probably tens of tonnes) can be swung around quite easily by hand because it is so finely balanced.

Armand



-------- Original message --------
From: valenzm@...
Date: 09-04-2013 4:50 PM (GMT-05:00)
To: ap-gto@...
Subject: [ap-gto] Counterweight Shaft Extension???


 

I'm new to AP equipment, new to astronomy, but fortunate to have an 1100GTO on the way in November. As I put together my kit, I have a question about counterweight configuration that might just be the newbie in me demonstrating inexperience.

I wrote to and spoke to the great people at AP about a useful combination of counterweights that might suit my needs. I plan to mount my FSQ106ED and/or Mewlon 250CRS, at times one or the other, at times both. The recommended counterweights for this was 3 X 18lbs and 1 X 10lbs to meet all the possible combinations, which I estimated were anywhere from 25 lbs up to 70 lbs.

Is there a breakdown in my logic when I think about the possibility of using a counterweight shaft extension to reduce the quantity of weight required by moving it farther from the axis of rotation? Does anyone successfully use a configuration such as this?

My motivation is less equipment to carry as I am almost exclusively traveling with my equipment to use it (I live in a townhouse). My limited experience is with my G-11 and the 21lbs weight it came with. I have that about 2/3rds up the shaft to balance my FSQ. Though I don't have a 10lbs, I have no doubt if I did it would work fine if it were closer to the end of the shaft.

I have to reiterate how great the people at AP are. The gentleman I spoke to took the time to go over part-by-part what I'll need for a tandem configuration, to place the 1100GTO atop my Losmandy FHD (I guessed - he confirmed), etc. They really are a first class company. I was recently told I'll soon have the last mount I'll ever want/need. What a pleasure these first experiences with their company have been.

Thank you in advance for your thoughts and suggestions.

Mark V


Re: Meridian Flip - Flop & Flexure compensation factor

Joe Zeglinski
 

Thanks for the confirmation, Rolando.
 
    Spent all last night using Pempro-2 to adjust the alignment, but as it turned out -  much to my regret - there wasn’t much to tweak to what I had done initially with my original manual drift alignment. The alignment seemed to be pretty decent already. Sky testing clouded out tonight, to see if it made any difference, or if the target comes closer to FOV on both sides of the pier.
 
    As for shimming, I am a little dubious about trying to slip a thin piece of copper under that hefty 75 lb scope. Not much room under the D-plate, or even knowing which end – fore or aft. Are there procedures to determine which way the OTA is tilted in its saddle, and roughly how thick a shim might be needed, and where to place the brass shim? Sure would be a neat feature to add to Pempro, or any other alignment software
 
    The software modeling approach might be the easiest.
 
Joe
 

Sent: Wednesday, September 04, 2013 3:36 PM
Subject: Re: [ap-gto] Meridian Flip - Flop & Flexure compensation factor
 


What you have is classic non-orthogonality. The scope optics point slightly different direction from the scope mechanical axis. Although it always looks like a mount problem, it is really simply an inherent offset in the scope itself. You can try shimming the mounting plate, or you can use one of the software programs to compensate for this offset.
 
Rolando


Re: Frustrating guiding problem

rags_the_cat
 

I'm surprised to hear you couldn't get Lodestar to work with PHD. It's my standard combo and have had no troubles with it ever.

Jerry


On Sep 4, 2013, at 4:11 PM, "CurtisC" <calypte@...> wrote:

 

> - The Lodestar doesn't work under MaximDL

There was a version of MaxIm that didn't work with Lodestar. Be sure you have the latest version of MaxIm. Of course, be sure you also have the latest driver for the Lodestar. But the Lodestar driver probably isn't your problem. As for PHD, I couldn't get it to work at all. Stick with MaxIm.


Re: Frustrating guiding problem

CurtisC <calypte@...>
 

- The Lodestar doesn't work under MaximDL
There was a version of MaxIm that didn't work with Lodestar. Be sure you have the latest version of MaxIm. Of course, be sure you also have the latest driver for the Lodestar. But the Lodestar driver probably isn't your problem. As for PHD, I couldn't get it to work at all. Stick with MaxIm.


Re: Frustrating guiding problem

parijat_singh
 

Leonardo,

 

Make the DEC worm mesh such that the gear on the worm is as easy to turn as possible (with fingers) while making sure you cannot feel the backlash on the axis (i.e. manually trying to move it with clutches tight).

It might take some time to get it right but it does not need to be done often.


Parijat



--- In ap-gto@..., <l.priami@...> wrote:

Peter,
I followed all that instruction. No problem of screw loosening was being detected. All is fine.
Only a doubt about how much hard the worm gear should be turned by hand during pressure force setting. It is difficult to say and also to understand.

Leonardo

Il 04/09/2013 22.19, topboxman2000 ha scritto:
 



Hi Leonardo,

I am not sure what else to say. Take a look at this to see if that's what you are seeing:

http://www.astro-physics.com/tech_support/mounts/backlash2.pdf

Peter

--- In ap-gto@..., Leonardo Priami <l.priami@...> wrote:
>
> Hi Peter,
> thanks for your help.
> About your suggestion:
> - I see (below the PHD screen) that the bigger correction are around
> 150/300 ms, but only when after a few attempt the mount still remain out.
>
> - About the exposure time I set to 3 or 4 seconds. I agree. But still I
> see some jumps as you can see in the pictures I show.
>
> - I can't use the OAG in the main scope because I have only 4 mm from
> the 3"Wynne corrector and the filter wheel flange.
>
> - The FSQ is piggybacked but with very strong system. I would exclude
> flexure.
>
> What I suspect is some "elasticity" somewhere in the gear train that
> bring the motor to rotate a bit and no rotation to the worm gear.
> I think that may occur some stick-slip phenomena between the worm gear
> and the wheel. After have accumulated sufficient force, than the
> movement will take place, realizing too much movement than requested and
> not when requested.
>
> What do you think about?
>
> Thanks,
>
> Leonardo
>
>
> Il 04/09/2013 17.13, topboxman2000 ha scritto:
> >
> >
> >
> > Hi Leonardo,
> >
> > Your Max Dec Duration of 600msec may be a little too high. Check the
> > log if Dec correction ever hit 600msec. A-P mounts are too smooth and
> > normally have very little to no backlash so Max Dec Duration should
> > not have to be this high. If the seeing is not good and setting Max
> > Dec Duration a little high could cause overshooting. Try set it to as
> > low as 75msec.
> >
> > Also the Min Motion might be a little too small. Small Min Motion can
> > send too many corrections to the mount.
> >
> > Because your mount is high end, I would set the guide exposure times
> > to at least 3 seconds to balance out the seeing and improve guide star
> > image (higher SNR).
> >
> > Can you use OAG for your bigger scope? You can get differential
> > flexure between guide and main scope. You said the guide scope is in
> > parallel with main scope, do you mean side by side or piggyback?
> >
> > Peter
> >
> > --- In ap-gto@..., Leonardo Priami <l.priami@> wrote:
> > >
> > > Sorry, here the link to see the screen shots:
> > >
> > > http://www.lpriami.altervista.org/ImAstro/Service.html
> > >
> > > Thanks for help!
> > >
> > > Leonardo
> > >
> > > Il 04/09/2013 11.37, Leonardo Priami ha scritto:
> > > >
> > > > Hi,
> > > > sorry to being here only when I'm frustrated about something.
> > > >
> > > > Here about the guiding of my AP1200 CP2.
> > > > The handpad has the 4.17 v firmware and the last V2 driver.
> > > >
> > > > - I have a Newton-Wynne 300 mm f/3,8 (1140 mm of focal length) with an
> > > > Apogee U16M and in parallel a FSQ106 (530 mm) with a Apogee F9 (both
> > > > camera with 9 micron pixel).
> > > > - On the main telescope I have a FWHM star about 1,3/1,5 pixel
> > (2,1/2,5
> > > > "), On the FSQ I have a FWHM about 1 pixel.
> > > > - The guiding is performed by a Starlight Lodestar using a MMoag
> > > > off-axis on the FSQ. (3,3/3,4 "/pixel).
> > > > With this parameters I see that I need to perform a guiding with a P-V
> > > > error less than 0,5 pixel (+/- 0,25 pixel). If I found oval stars when
> > > > the error goes to 0,5 pixel.
> > > > - The cable connects directly the Lodestar with the mount.
> > > > - The Lodestar doesn't work under MaximDL, neither with its driver,
> > > > neither with its Ascom driver (it perform a too short calibration even
> > > > if I set 40 sec on setting...)
> > > > -The guiding is performed with PHD
> > > > -The DEC balancing is perfect (may be necessary a little
> > un-balancing?)
> > > > -Polar alignment is very good (I have a Dec Drift of about 1 pixel on
> > > > guider after 10/15 min)
> > > > -I tried more time to adjust the Dec backlash as suggested on the AP
> > > > site. The Dec warm gear shaft can be turn by hand from the gear side
> > > > (dismounting the first gear).
> > > > - Moving manually the gears I see a back-lash of about 1 tooth on the
> > > > first motor gear, moving with handpad I see about of less than 1
> > sec at
> > > > 0,5X to compensate a "1 tooth" backlash (so about 7 arcsec to set
> > the V2
> > > > driver?)
> > > > -I tried with 0,5X and 0,25X without improvement
> > > > -I tried 2s, 3s, and 4 sec, the seeing is 2,3" FWHM, with 4 s I see
> > > > better results, but still I have some Dec jumps
> > > >
> > > > Principally I tried to set "Auto" on the Dec guide setting on PHD,
> > but I
> > > > see a lot of jumps.
> > > > Selecting only one direction the performance is better, but I see some
> > > > jumps every 2-3 min. Also RA seems some times to be correlated.
> > > > I attached three shot that show the graphs. The red line is the Dec.
> > > > Some suggestion to solve?
> > > > Thanks a lot!
> > > >
> > > > Regards,
> > > >
> > > > Leonardo Priami
> > > >
> > > > [Non-text portions of this message have been removed]
> > > >
> > > >
> > >
> >
> >
>



Counterweight Shaft Extension???

Mark Valenz
 

I'm new to AP equipment, new to astronomy, but fortunate to have an 1100GTO on the way in November. As I put together my kit, I have a question about counterweight configuration that might just be the newbie in me demonstrating inexperience.

I wrote to and spoke to the great people at AP about a useful combination of counterweights that might suit my needs. I plan to mount my FSQ106ED and/or Mewlon 250CRS, at times one or the other, at times both. The recommended counterweights for this was 3 X 18lbs and 1 X 10lbs to meet all the possible combinations, which I estimated were anywhere from 25 lbs up to 70 lbs.

Is there a breakdown in my logic when I think about the possibility of using a counterweight shaft extension to reduce the quantity of weight required by moving it farther from the axis of rotation? Does anyone successfully use a configuration such as this?

My motivation is less equipment to carry as I am almost exclusively traveling with my equipment to use it (I live in a townhouse). My limited experience is with my G-11 and the 21lbs weight it came with. I have that about 2/3rds up the shaft to balance my FSQ. Though I don't have a 10lbs, I have no doubt if I did it would work fine if it were closer to the end of the shaft.

I have to reiterate how great the people at AP are. The gentleman I spoke to took the time to go over part-by-part what I'll need for a tandem configuration, to place the 1100GTO atop my Losmandy FHD (I guessed - he confirmed), etc. They really are a first class company. I was recently told I'll soon have the last mount I'll ever want/need. What a pleasure these first experiences with their company have been.

Thank you in advance for your thoughts and suggestions.

Mark V


Re: Frustrating guiding problem

Leonardo Priami
 

Yes Ram!
During adjust mesh following the AP technical support, My doubt is reading this:
"After you have exposed worm shaft extension, you should be able to turn it by hand or with a pair of pliers with tape over the jaws. If you can turn it, please proceed to step 9. If the worm shaft extension is tight, please proceed to step 10."

This recomandation seems really to be not clear! By hand or with a pair of pliers ...I can generate a wide range of force!!

Could someone to be more precise to explain how to understand if our gear meshes are too tight or too loose?

Thanks a lot!

Leonardo

Leonardo,
I encountered exactly the same issue this past weekend with my older (600E)
mount. I adjusted the RA and DEC mesh the previous night before I started
imaging so it is possible that my mesh was set too tight leading to
stiction. I believe this is what you refer to as elasticity.

In the meantime it might be worthwhile trying the following:
1. Turn off DEC backlash compensation in PhD. It is possible that PhD is
overcompensating for backlash by moving it too far.
2. Try to set your DEC to north or south rather than auto. This way you
aren't changing directions and having to deal with Backlash.


I was unable to test out the above since it got too windy (and then cloudy)
after I discovered the issue.

I look forward to hearing your results.

--Ram



On Wed, Sep 4, 2013 at 1:04 PM, Leonardo Priami <l.priami@...> wrote:

**


Hi Peter,
thanks for your help.
About your suggestion:
- I see (below the PHD screen) that the bigger correction are around
150/300 ms, but only when after a few attempt the mount still remain out.

- About the exposure time I set to 3 or 4 seconds. I agree. But still I
see some jumps as you can see in the pictures I show.

- I can't use the OAG in the main scope because I have only 4 mm from the
3"Wynne corrector and the filter wheel flange.

- The FSQ is piggybacked but with very strong system. I would exclude
flexure.

What I suspect is some "elasticity" somewhere in the gear train that bring
the motor to rotate a bit and no rotation to the worm gear.
I think that may occur some stick-slip phenomena between the worm gear and
the wheel. After have accumulated sufficient force, than the movement will
take place, realizing too much movement than requested and not when
requested.

What do you think about?

Thanks,

Leonardo


Il 04/09/2013 17.13, topboxman2000 ha scritto:





Hi Leonardo,

Your Max Dec Duration of 600msec may be a little too high. Check the log
if Dec correction ever hit 600msec. A-P mounts are too smooth and normally
have very little to no backlash so Max Dec Duration should not have to be
this high. If the seeing is not good and setting Max Dec Duration a little
high could cause overshooting. Try set it to as low as 75msec.

Also the Min Motion might be a little too small. Small Min Motion can send
too many corrections to the mount.

Because your mount is high end, I would set the guide exposure times to at
least 3 seconds to balance out the seeing and improve guide star image
(higher SNR).

Can you use OAG for your bigger scope? You can get differential flexure
between guide and main scope. You said the guide scope is in parallel with
main scope, do you mean side by side or piggyback?

Peter

--- In ap-gto@..., Leonardo Priami <l.priami@...><l.priami@...>wrote:

Sorry, here the link to see the screen shots:

http://www.lpriami.altervista.org/ImAstro/Service.html

Thanks for help!

Leonardo

Il 04/09/2013 11.37, Leonardo Priami ha scritto:

Hi,
sorry to being here only when I'm frustrated about something.

Here about the guiding of my AP1200 CP2.
The handpad has the 4.17 v firmware and the last V2 driver.

- I have a Newton-Wynne 300 mm f/3,8 (1140 mm of focal length) with an
Apogee U16M and in parallel a FSQ106 (530 mm) with a Apogee F9 (both
camera with 9 micron pixel).
- On the main telescope I have a FWHM star about 1,3/1,5 pixel (2,1/2,5
"), On the FSQ I have a FWHM about 1 pixel.
- The guiding is performed by a Starlight Lodestar using a MMoag
off-axis on the FSQ. (3,3/3,4 "/pixel).
With this parameters I see that I need to perform a guiding with a P-V
error less than 0,5 pixel (+/- 0,25 pixel). If I found oval stars when
the error goes to 0,5 pixel.
- The cable connects directly the Lodestar with the mount.
- The Lodestar doesn't work under MaximDL, neither with its driver,
neither with its Ascom driver (it perform a too short calibration even
if I set 40 sec on setting...)
-The guiding is performed with PHD
-The DEC balancing is perfect (may be necessary a little un-balancing?)
-Polar alignment is very good (I have a Dec Drift of about 1 pixel on
guider after 10/15 min)
-I tried more time to adjust the Dec backlash as suggested on the AP
site. The Dec warm gear shaft can be turn by hand from the gear side
(dismounting the first gear).
- Moving manually the gears I see a back-lash of about 1 tooth on the
first motor gear, moving with handpad I see about of less than 1 sec at
0,5X to compensate a "1 tooth" backlash (so about 7 arcsec to set the
V2
driver?)
-I tried with 0,5X and 0,25X without improvement
-I tried 2s, 3s, and 4 sec, the seeing is 2,3" FWHM, with 4 s I see
better results, but still I have some Dec jumps

Principally I tried to set "Auto" on the Dec guide setting on PHD, but
I
see a lot of jumps.
Selecting only one direction the performance is better, but I see some
jumps every 2-3 min. Also RA seems some times to be correlated.
I attached three shot that show the graphs. The red line is the Dec.
Some suggestion to solve?
Thanks a lot!

Regards,

Leonardo Priami






Re: Frustrating guiding problem

Leonardo Priami
 

Peter,
I followed all that instruction. No problem of screw loosening was being detected. All is fine.
Only a doubt about how much hard the worm gear should be turned by hand during pressure force setting. It is difficult to say and also to understand.

Leonardo

Il 04/09/2013 22.19, topboxman2000 ha scritto:
 



Hi Leonardo,

I am not sure what else to say. Take a look at this to see if that's what you are seeing:

http://www.astro-physics.com/tech_support/mounts/backlash2.pdf

Peter

--- In ap-gto@..., Leonardo Priami wrote:
>
> Hi Peter,
> thanks for your help.
> About your suggestion:
> - I see (below the PHD screen) that the bigger correction are around
> 150/300 ms, but only when after a few attempt the mount still remain out.
>
> - About the exposure time I set to 3 or 4 seconds. I agree. But still I
> see some jumps as you can see in the pictures I show.
>
> - I can't use the OAG in the main scope because I have only 4 mm from
> the 3"Wynne corrector and the filter wheel flange.
>
> - The FSQ is piggybacked but with very strong system. I would exclude
> flexure.
>
> What I suspect is some "elasticity" somewhere in the gear train that
> bring the motor to rotate a bit and no rotation to the worm gear.
> I think that may occur some stick-slip phenomena between the worm gear
> and the wheel. After have accumulated sufficient force, than the
> movement will take place, realizing too much movement than requested and
> not when requested.
>
> What do you think about?
>
> Thanks,
>
> Leonardo
>
>
> Il 04/09/2013 17.13, topboxman2000 ha scritto:
> >
> >
> >
> > Hi Leonardo,
> >
> > Your Max Dec Duration of 600msec may be a little too high. Check the
> > log if Dec correction ever hit 600msec. A-P mounts are too smooth and
> > normally have very little to no backlash so Max Dec Duration should
> > not have to be this high. If the seeing is not good and setting Max
> > Dec Duration a little high could cause overshooting. Try set it to as
> > low as 75msec.
> >
> > Also the Min Motion might be a little too small. Small Min Motion can
> > send too many corrections to the mount.
> >
> > Because your mount is high end, I would set the guide exposure times
> > to at least 3 seconds to balance out the seeing and improve guide star
> > image (higher SNR).
> >
> > Can you use OAG for your bigger scope? You can get differential
> > flexure between guide and main scope. You said the guide scope is in
> > parallel with main scope, do you mean side by side or piggyback?
> >
> > Peter
> >
> > --- In ap-gto@..., Leonardo Priami wrote:
> > >
> > > Sorry, here the link to see the screen shots:
> > >
> > > http://www.lpriami.altervista.org/ImAstro/Service.html
> > >
> > > Thanks for help!
> > >
> > > Leonardo
> > >
> > > Il 04/09/2013 11.37, Leonardo Priami ha scritto:
> > > >
> > > > Hi,
> > > > sorry to being here only when I'm frustrated about something.
> > > >
> > > > Here about the guiding of my AP1200 CP2.
> > > > The handpad has the 4.17 v firmware and the last V2 driver.
> > > >
> > > > - I have a Newton-Wynne 300 mm f/3,8 (1140 mm of focal length) with an
> > > > Apogee U16M and in parallel a FSQ106 (530 mm) with a Apogee F9 (both
> > > > camera with 9 micron pixel).
> > > > - On the main telescope I have a FWHM star about 1,3/1,5 pixel
> > (2,1/2,5
> > > > "), On the FSQ I have a FWHM about 1 pixel.
> > > > - The guiding is performed by a Starlight Lodestar using a MMoag
> > > > off-axis on the FSQ. (3,3/3,4 "/pixel).
> > > > With this parameters I see that I need to perform a guiding with a P-V
> > > > error less than 0,5 pixel (+/- 0,25 pixel). If I found oval stars when
> > > > the error goes to 0,5 pixel.
> > > > - The cable connects directly the Lodestar with the mount.
> > > > - The Lodestar doesn't work under MaximDL, neither with its driver,
> > > > neither with its Ascom driver (it perform a too short calibration even
> > > > if I set 40 sec on setting...)
> > > > -The guiding is performed with PHD
> > > > -The DEC balancing is perfect (may be necessary a little
> > un-balancing?)
> > > > -Polar alignment is very good (I have a Dec Drift of about 1 pixel on
> > > > guider after 10/15 min)
> > > > -I tried more time to adjust the Dec backlash as suggested on the AP
> > > > site. The Dec warm gear shaft can be turn by hand from the gear side
> > > > (dismounting the first gear).
> > > > - Moving manually the gears I see a back-lash of about 1 tooth on the
> > > > first motor gear, moving with handpad I see about of less than 1
> > sec at
> > > > 0,5X to compensate a "1 tooth" backlash (so about 7 arcsec to set
> > the V2
> > > > driver?)
> > > > -I tried with 0,5X and 0,25X without improvement
> > > > -I tried 2s, 3s, and 4 sec, the seeing is 2,3" FWHM, with 4 s I see
> > > > better results, but still I have some Dec jumps
> > > >
> > > > Principally I tried to set "Auto" on the Dec guide setting on PHD,
> > but I
> > > > see a lot of jumps.
> > > > Selecting only one direction the performance is better, but I see some
> > > > jumps every 2-3 min. Also RA seems some times to be correlated.
> > > > I attached three shot that show the graphs. The red line is the Dec.
> > > > Some suggestion to solve?
> > > > Thanks a lot!
> > > >
> > > > Regards,
> > > >
> > > > Leonardo Priami
> > > >
> > > > [Non-text portions of this message have been removed]
> > > >
> > > >
> > >
> >
> >
>



Re: Frustrating guiding problem

Ram
 

Leonardo,
I encountered exactly the same issue this past weekend with my older (600E) mount. I adjusted the RA and DEC mesh the previous night before I started imaging so it is possible that my mesh was set too tight leading to stiction. I believe this is what you refer to as elasticity.

In the meantime it might be worthwhile trying the following:
1. Turn off DEC backlash compensation in PhD. It is possible that PhD is overcompensating for backlash by moving it too far.
2. Try to set your DEC to north or south rather than auto. This way you aren't changing directions and having to deal with Backlash.


I was unable to test out the above since it got too windy (and then cloudy) after I discovered the issue.

I look forward to hearing your results. 

--Ram



On Wed, Sep 4, 2013 at 1:04 PM, Leonardo Priami <l.priami@...> wrote:
 

Hi Peter,
thanks for your help.
About your suggestion:
- I see (below the PHD screen) that the bigger correction are around 150/300 ms, but only when after a few attempt the mount still remain out.

- About the exposure time I set to 3 or 4 seconds. I agree. But still I see some jumps as you can see in the pictures I show.

- I can't use the OAG in the main scope because I have only 4 mm from the 3"Wynne corrector and the filter wheel flange.

- The FSQ is piggybacked but with very strong system. I would exclude flexure.

What I suspect is some "elasticity" somewhere in the gear train that bring the motor to rotate a bit and no rotation to the worm gear.
I think that may occur some stick-slip phenomena between the worm gear and the wheel. After have  accumulated sufficient force, than the movement will take place, realizing too much movement than requested and not when requested.

What do you think about?

Thanks,

Leonardo


Il 04/09/2013 17.13, topboxman2000 ha scritto:
 



Hi Leonardo,

Your Max Dec Duration of 600msec may be a little too high. Check the log if Dec correction ever hit 600msec. A-P mounts are too smooth and normally have very little to no backlash so Max Dec Duration should not have to be this high. If the seeing is not good and setting Max Dec Duration a little high could cause overshooting. Try set it to as low as 75msec.

Also the Min Motion might be a little too small. Small Min Motion can send too many corrections to the mount.

Because your mount is high end, I would set the guide exposure times to at least 3 seconds to balance out the seeing and improve guide star image (higher SNR).

Can you use OAG for your bigger scope? You can get differential flexure between guide and main scope. You said the guide scope is in parallel with main scope, do you mean side by side or piggyback?

Peter

--- In ap-gto@..., Leonardo Priami <l.priami@...> wrote:
>
> Sorry, here the link to see the screen shots:
>
> http://www.lpriami.altervista.org/ImAstro/Service.html
>
> Thanks for help!
>
> Leonardo
>
> Il 04/09/2013 11.37, Leonardo Priami ha scritto:
> >
> > Hi,
> > sorry to being here only when I'm frustrated about something.
> >
> > Here about the guiding of my AP1200 CP2.
> > The handpad has the 4.17 v firmware and the last V2 driver.
> >
> > - I have a Newton-Wynne 300 mm f/3,8 (1140 mm of focal length) with an
> > Apogee U16M and in parallel a FSQ106 (530 mm) with a Apogee F9 (both
> > camera with 9 micron pixel).
> > - On the main telescope I have a FWHM star about 1,3/1,5 pixel (2,1/2,5
> > "), On the FSQ I have a FWHM about 1 pixel.
> > - The guiding is performed by a Starlight Lodestar using a MMoag
> > off-axis on the FSQ. (3,3/3,4 "/pixel).
> > With this parameters I see that I need to perform a guiding with a P-V
> > error less than 0,5 pixel (+/- 0,25 pixel). If I found oval stars when
> > the error goes to 0,5 pixel.
> > - The cable connects directly the Lodestar with the mount.
> > - The Lodestar doesn't work under MaximDL, neither with its driver,
> > neither with its Ascom driver (it perform a too short calibration even
> > if I set 40 sec on setting...)
> > -The guiding is performed with PHD
> > -The DEC balancing is perfect (may be necessary a little un-balancing?)
> > -Polar alignment is very good (I have a Dec Drift of about 1 pixel on
> > guider after 10/15 min)
> > -I tried more time to adjust the Dec backlash as suggested on the AP
> > site. The Dec warm gear shaft can be turn by hand from the gear side
> > (dismounting the first gear).
> > - Moving manually the gears I see a back-lash of about 1 tooth on the
> > first motor gear, moving with handpad I see about of less than 1 sec at
> > 0,5X to compensate a "1 tooth" backlash (so about 7 arcsec to set the V2
> > driver?)
> > -I tried with 0,5X and 0,25X without improvement
> > -I tried 2s, 3s, and 4 sec, the seeing is 2,3" FWHM, with 4 s I see
> > better results, but still I have some Dec jumps
> >
> > Principally I tried to set "Auto" on the Dec guide setting on PHD, but I
> > see a lot of jumps.
> > Selecting only one direction the performance is better, but I see some
> > jumps every 2-3 min. Also RA seems some times to be correlated.
> > I attached three shot that show the graphs. The red line is the Dec.
> > Some suggestion to solve?
> > Thanks a lot!
> >
> > Regards,
> >
> > Leonardo Priami
> >
> > [Non-text portions of this message have been removed]
> >
> >
>




Re: Frustrating guiding problem

topboxman
 

Hi Leonardo,

I am not sure what else to say. Take a look at this to see if that's what you are seeing:

http://www.astro-physics.com/tech_support/mounts/backlash2.pdf

Peter

--- In ap-gto@..., Leonardo Priami <l.priami@...> wrote:

Hi Peter,
thanks for your help.
About your suggestion:
- I see (below the PHD screen) that the bigger correction are around
150/300 ms, but only when after a few attempt the mount still remain out.

- About the exposure time I set to 3 or 4 seconds. I agree. But still I
see some jumps as you can see in the pictures I show.

- I can't use the OAG in the main scope because I have only 4 mm from
the 3"Wynne corrector and the filter wheel flange.

- The FSQ is piggybacked but with very strong system. I would exclude
flexure.

What I suspect is some "elasticity" somewhere in the gear train that
bring the motor to rotate a bit and no rotation to the worm gear.
I think that may occur some stick-slip phenomena between the worm gear
and the wheel. After have accumulated sufficient force, than the
movement will take place, realizing too much movement than requested and
not when requested.

What do you think about?

Thanks,

Leonardo


Il 04/09/2013 17.13, topboxman2000 ha scritto:



Hi Leonardo,

Your Max Dec Duration of 600msec may be a little too high. Check the
log if Dec correction ever hit 600msec. A-P mounts are too smooth and
normally have very little to no backlash so Max Dec Duration should
not have to be this high. If the seeing is not good and setting Max
Dec Duration a little high could cause overshooting. Try set it to as
low as 75msec.

Also the Min Motion might be a little too small. Small Min Motion can
send too many corrections to the mount.

Because your mount is high end, I would set the guide exposure times
to at least 3 seconds to balance out the seeing and improve guide star
image (higher SNR).

Can you use OAG for your bigger scope? You can get differential
flexure between guide and main scope. You said the guide scope is in
parallel with main scope, do you mean side by side or piggyback?

Peter

--- In ap-gto@..., Leonardo Priami <l.priami@> wrote:

Sorry, here the link to see the screen shots:

http://www.lpriami.altervista.org/ImAstro/Service.html

Thanks for help!

Leonardo

Il 04/09/2013 11.37, Leonardo Priami ha scritto:

Hi,
sorry to being here only when I'm frustrated about something.

Here about the guiding of my AP1200 CP2.
The handpad has the 4.17 v firmware and the last V2 driver.

- I have a Newton-Wynne 300 mm f/3,8 (1140 mm of focal length) with an
Apogee U16M and in parallel a FSQ106 (530 mm) with a Apogee F9 (both
camera with 9 micron pixel).
- On the main telescope I have a FWHM star about 1,3/1,5 pixel
(2,1/2,5
"), On the FSQ I have a FWHM about 1 pixel.
- The guiding is performed by a Starlight Lodestar using a MMoag
off-axis on the FSQ. (3,3/3,4 "/pixel).
With this parameters I see that I need to perform a guiding with a P-V
error less than 0,5 pixel (+/- 0,25 pixel). If I found oval stars when
the error goes to 0,5 pixel.
- The cable connects directly the Lodestar with the mount.
- The Lodestar doesn't work under MaximDL, neither with its driver,
neither with its Ascom driver (it perform a too short calibration even
if I set 40 sec on setting...)
-The guiding is performed with PHD
-The DEC balancing is perfect (may be necessary a little
un-balancing?)
-Polar alignment is very good (I have a Dec Drift of about 1 pixel on
guider after 10/15 min)
-I tried more time to adjust the Dec backlash as suggested on the AP
site. The Dec warm gear shaft can be turn by hand from the gear side
(dismounting the first gear).
- Moving manually the gears I see a back-lash of about 1 tooth on the
first motor gear, moving with handpad I see about of less than 1
sec at
0,5X to compensate a "1 tooth" backlash (so about 7 arcsec to set
the V2
driver?)
-I tried with 0,5X and 0,25X without improvement
-I tried 2s, 3s, and 4 sec, the seeing is 2,3" FWHM, with 4 s I see
better results, but still I have some Dec jumps

Principally I tried to set "Auto" on the Dec guide setting on PHD,
but I
see a lot of jumps.
Selecting only one direction the performance is better, but I see some
jumps every 2-3 min. Also RA seems some times to be correlated.
I attached three shot that show the graphs. The red line is the Dec.
Some suggestion to solve?
Thanks a lot!

Regards,

Leonardo Priami

[Non-text portions of this message have been removed]


Re: Frustrating guiding problem

Leonardo Priami
 

Hi Peter,
thanks for your help.
About your suggestion:
- I see (below the PHD screen) that the bigger correction are around 150/300 ms, but only when after a few attempt the mount still remain out.

- About the exposure time I set to 3 or 4 seconds. I agree. But still I see some jumps as you can see in the pictures I show.

- I can't use the OAG in the main scope because I have only 4 mm from the 3"Wynne corrector and the filter wheel flange.

- The FSQ is piggybacked but with very strong system. I would exclude flexure.

What I suspect is some "elasticity" somewhere in the gear train that bring the motor to rotate a bit and no rotation to the worm gear.
I think that may occur some stick-slip phenomena between the worm gear and the wheel. After have  accumulated sufficient force, than the movement will take place, realizing too much movement than requested and not when requested.

What do you think about?

Thanks,

Leonardo


Il 04/09/2013 17.13, topboxman2000 ha scritto:
 



Hi Leonardo,

Your Max Dec Duration of 600msec may be a little too high. Check the log if Dec correction ever hit 600msec. A-P mounts are too smooth and normally have very little to no backlash so Max Dec Duration should not have to be this high. If the seeing is not good and setting Max Dec Duration a little high could cause overshooting. Try set it to as low as 75msec.

Also the Min Motion might be a little too small. Small Min Motion can send too many corrections to the mount.

Because your mount is high end, I would set the guide exposure times to at least 3 seconds to balance out the seeing and improve guide star image (higher SNR).

Can you use OAG for your bigger scope? You can get differential flexure between guide and main scope. You said the guide scope is in parallel with main scope, do you mean side by side or piggyback?

Peter

--- In ap-gto@..., Leonardo Priami wrote:
>
> Sorry, here the link to see the screen shots:
>
> http://www.lpriami.altervista.org/ImAstro/Service.html
>
> Thanks for help!
>
> Leonardo
>
> Il 04/09/2013 11.37, Leonardo Priami ha scritto:
> >
> > Hi,
> > sorry to being here only when I'm frustrated about something.
> >
> > Here about the guiding of my AP1200 CP2.
> > The handpad has the 4.17 v firmware and the last V2 driver.
> >
> > - I have a Newton-Wynne 300 mm f/3,8 (1140 mm of focal length) with an
> > Apogee U16M and in parallel a FSQ106 (530 mm) with a Apogee F9 (both
> > camera with 9 micron pixel).
> > - On the main telescope I have a FWHM star about 1,3/1,5 pixel (2,1/2,5
> > "), On the FSQ I have a FWHM about 1 pixel.
> > - The guiding is performed by a Starlight Lodestar using a MMoag
> > off-axis on the FSQ. (3,3/3,4 "/pixel).
> > With this parameters I see that I need to perform a guiding with a P-V
> > error less than 0,5 pixel (+/- 0,25 pixel). If I found oval stars when
> > the error goes to 0,5 pixel.
> > - The cable connects directly the Lodestar with the mount.
> > - The Lodestar doesn't work under MaximDL, neither with its driver,
> > neither with its Ascom driver (it perform a too short calibration even
> > if I set 40 sec on setting...)
> > -The guiding is performed with PHD
> > -The DEC balancing is perfect (may be necessary a little un-balancing?)
> > -Polar alignment is very good (I have a Dec Drift of about 1 pixel on
> > guider after 10/15 min)
> > -I tried more time to adjust the Dec backlash as suggested on the AP
> > site. The Dec warm gear shaft can be turn by hand from the gear side
> > (dismounting the first gear).
> > - Moving manually the gears I see a back-lash of about 1 tooth on the
> > first motor gear, moving with handpad I see about of less than 1 sec at
> > 0,5X to compensate a "1 tooth" backlash (so about 7 arcsec to set the V2
> > driver?)
> > -I tried with 0,5X and 0,25X without improvement
> > -I tried 2s, 3s, and 4 sec, the seeing is 2,3" FWHM, with 4 s I see
> > better results, but still I have some Dec jumps
> >
> > Principally I tried to set "Auto" on the Dec guide setting on PHD, but I
> > see a lot of jumps.
> > Selecting only one direction the performance is better, but I see some
> > jumps every 2-3 min. Also RA seems some times to be correlated.
> > I attached three shot that show the graphs. The red line is the Dec.
> > Some suggestion to solve?
> > Thanks a lot!
> >
> > Regards,
> >
> > Leonardo Priami
> >
> > [Non-text portions of this message have been removed]
> >
> >
>



Re: Meridian Flip - Flop & Flexure compensation factor

Roland Christen
 

What you have is classic non-orthogonality. The scope optics point slightly different direction from the scope mechanical axis. Although it always looks like a mount problem, it is really simply an inherent offset in the scope itself. You can try shimming the mounting plate, or you can use one of the software programs to compensate for this offset.
 
Rolando 


-----Original Message-----
From: Joseph Zeglinski
To: ap-gto
Sent: Tue, Sep 3, 2013 1:00 pm
Subject: Re: [ap-gto] Meridian Flip - Flop & Flexure compensation factor

Hi Ram,

    Yes, that is basically what I do ... every time the mount changes sides.

    Last night I just got tired of this exercise, and figured it would be
much easier to have a compensation factor - which I have to apply anyway,
with this problem. I was imaging M57 last night, right at the zenith, on
both sides of the flip, and realized that with that same target directly
overhead, there really shouldn't be a flexure or mirror flop problem, since
the OTA and mirror start and end at exactly the same position - mirror
resting flat, OTA straight up, neither is stressed or imbalanced. The only
change is mount's pier side. Flexure and any mirror flop should have
resettled themselves after the 180 degree contortion to get to the other
side.  If I re-flip, (without a doing a RCAL on the other side), the mount
still centres , on the same target back at the original position on the
original side of the pier. The reversed translation is perfect, so any
mirror flop or flex, is repeatable, and if present, re-adjusts itself
without any change.

    The only remaining minor suspicion, at the back of my mind, is whether
the new DOVELM162 saddle "twists around ever so slightly" around its four
attachment screws, during the rotation of the meridian flip. But, I torqued
them all tightly, short of stripping the threads in the mount head itself. I
have also tightened all other locking bolts and clutches with a hex wrench,
and the OTA is perfectly balanced fore & aft, so the mount should be rock
solid. The only difference is that the heavy OTA is resting on the plate,
then hanging from it on the flip side. But at a near-zenith target, the
difference should be minimal.

    I, as many others, am eager to finally see the arrival of the APCC.

Joe



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Re: Frustrating guiding problem

topboxman
 

Hi Leonardo,

Your Max Dec Duration of 600msec may be a little too high. Check the log if Dec correction ever hit 600msec. A-P mounts are too smooth and normally have very little to no backlash so Max Dec Duration should not have to be this high. If the seeing is not good and setting Max Dec Duration a little high could cause overshooting. Try set it to as low as 75msec.

Also the Min Motion might be a little too small. Small Min Motion can send too many corrections to the mount.

Because your mount is high end, I would set the guide exposure times to at least 3 seconds to balance out the seeing and improve guide star image (higher SNR).

Can you use OAG for your bigger scope? You can get differential flexure between guide and main scope. You said the guide scope is in parallel with main scope, do you mean side by side or piggyback?

Peter

--- In ap-gto@..., Leonardo Priami <l.priami@...> wrote:

Sorry, here the link to see the screen shots:

http://www.lpriami.altervista.org/ImAstro/Service.html

Thanks for help!

Leonardo

Il 04/09/2013 11.37, Leonardo Priami ha scritto:

Hi,
sorry to being here only when I'm frustrated about something.

Here about the guiding of my AP1200 CP2.
The handpad has the 4.17 v firmware and the last V2 driver.

- I have a Newton-Wynne 300 mm f/3,8 (1140 mm of focal length) with an
Apogee U16M and in parallel a FSQ106 (530 mm) with a Apogee F9 (both
camera with 9 micron pixel).
- On the main telescope I have a FWHM star about 1,3/1,5 pixel (2,1/2,5
"), On the FSQ I have a FWHM about 1 pixel.
- The guiding is performed by a Starlight Lodestar using a MMoag
off-axis on the FSQ. (3,3/3,4 "/pixel).
With this parameters I see that I need to perform a guiding with a P-V
error less than 0,5 pixel (+/- 0,25 pixel). If I found oval stars when
the error goes to 0,5 pixel.
- The cable connects directly the Lodestar with the mount.
- The Lodestar doesn't work under MaximDL, neither with its driver,
neither with its Ascom driver (it perform a too short calibration even
if I set 40 sec on setting...)
-The guiding is performed with PHD
-The DEC balancing is perfect (may be necessary a little un-balancing?)
-Polar alignment is very good (I have a Dec Drift of about 1 pixel on
guider after 10/15 min)
-I tried more time to adjust the Dec backlash as suggested on the AP
site. The Dec warm gear shaft can be turn by hand from the gear side
(dismounting the first gear).
- Moving manually the gears I see a back-lash of about 1 tooth on the
first motor gear, moving with handpad I see about of less than 1 sec at
0,5X to compensate a "1 tooth" backlash (so about 7 arcsec to set the V2
driver?)
-I tried with 0,5X and 0,25X without improvement
-I tried 2s, 3s, and 4 sec, the seeing is 2,3" FWHM, with 4 s I see
better results, but still I have some Dec jumps

Principally I tried to set "Auto" on the Dec guide setting on PHD, but I
see a lot of jumps.
Selecting only one direction the performance is better, but I see some
jumps every 2-3 min. Also RA seems some times to be correlated.
I attached three shot that show the graphs. The red line is the Dec.
Some suggestion to solve?
Thanks a lot!

Regards,

Leonardo Priami