Date   

Re: 1100GTO not holding polar alignment

Joe Renzetti <axnyslie@...>
 

Thanks Im forecasted to have a clear night here tonight and tomorrow. With a near full moon it's a perfect time to take the gear out for tests. I checked the Losmandy HD tripod indoors securing all bolts in place. It has a 4" extension bolted on where the CP4 box attaches via CBAPT, so I don't need to extend the legs. Those knobs are now tightened down as best as I can. I use the Farpoint Astro Tripod Leg Knobs Set to attach the 1100 via the LT2APM maybe I'll switch to something more secure. It would be nice to have knobs that can also be locked down with an allen key like the 16" saddle (DOVELM162) I always lock my C14 down for peace of mind the 65lbs payload makes me a little nervous when slewing around. A quick remote setup is nice but not at the expense of it being less secure.

Joe

On Wed, Aug 22, 2018 at 7:32 AM, mike.hambrick@... [ap-gto] <ap-gto@...> wrote:
 

Hi Joe

I had a similar experience as yours with my 1100 mount shortly after I got it. I am also strictly a mobile user, setting up and taking down the mount in my back yard every time I use it. I am using the old 8-inch pier that came with my A-P 800 mount that I purchased in 1992, and I noticed the polar axis would sometimes shift during an observing session.

What I found in my case was that the top of the 8-inch pier was not completely flat. When assembling the mount I noticed a distinct wobble when I placed the base of the 1100 mount onto the top of the pier. I found that the top of the pier tube was not flat, and that the machined base of the 1100 mount was only making contact with the top of the pier in two places. I estimated that the base of the mount was tilting as much as 0.035". I could tighten the bolts holding the base of the mount onto the pier, but this was not enough to keep the assembled mount with the scope and counterweights from shifting under a load.

The solution was pretty simple. I coated the top of the pier with layout dye, placed the base of the mount on the pier, rotated it back and forth slightly, then removed the mount base. The high spots showed up as spots on the top of the pier where the dye had rubbed off. Using a file, I carefully filed the high spots (light and gentle touch on aluminum !!), recoated the top of the pier with layout dye, and repeated the process. It took about 45 minutes to get the base of the mount making uniform contact completely around the top of the pier. After doing this the episodes of shifting polar alignment stopped. 

I have long suspected that another potential source of polar shifting is due to the generous clearance between the bolt holes on the top of the pier and the 5/16-18 bolts that are used to attach the base of the mount to the pier. As long as the load is centered over the base of the mount, the assembled mount with scope and counterweights is is not likely to shift, but I think it would be better to have some alignment pins that positively lock the top of the pier and mount base in position. The current configuration of the 1100 mount uses six bolts to attach the base of the mount to the pier. I would like to see three of the bolts replaced with tapered dowel pins. This would provide a rock solid connection of the mount base to the pier that will not shift (assuming the top of the pier is flat). The only problem with tapered dowel pins is that they can really get stuck. A method of removing them has to be devised, but I'll bet that Roland's outstanding machinist can devise a very clever way to do this.

I hope that this helps. Good luck in solving your problem.



Slew rates

robert@...
 

Howdy boys and girls!


Last week I acquired a late 2015 Mach 1/CP4 that is in immaculate condition. I know the gentleman that I bought it from used it. I just can't prove it. There's nothing wrong with it, except one thing...


How much money in a GoFundMe campaign would it take to get a couple of slew speeds between 64x and 600x?? WHY is there such a speed difference? The two mount speeds seem to be screaming and creeping. I'm afraid to try 1200x -- I think the noise might shatter glass. The reason I ask is because I literally don't think I could take this mount to a campground in New Mexico without being met in the middle of the night by tent-dwellers carrying pitchforks and torches, which would not only ruin my night vision, but would probably hurt a bit. Isn't it quiet in Illinois at night? The dark campgrounds I go to around here are dead quiet at night, except for the occasional chupacabra. Aside from maybe using APCC (haven't looked into it, but don't really want to be using a laptop, big power supply, etc.) is there anything that can be done...other than large sums of money?


Other than this, nice mount! I was afraid not having the releasable gearboxes would be a problem, but the axes seem to be loose enough to get things balanced just fine. Big step up from my pusher GM-8. Of course, I've only been able to play with it in the living room. The mount is afraid of the thunder. NOW, this week, the monsoons decide to kick in.


Thanks!


Bob :)



Re: 1100GTO not holding polar alignment

mike.hambrick@...
 

Hi Joe

I had a similar experience as yours with my 1100 mount shortly after I got it. I am also strictly a mobile user, setting up and taking down the mount in my back yard every time I use it. I am using the old 8-inch pier that came with my A-P 800 mount that I purchased in 1992, and I noticed the polar axis would sometimes shift during an observing session.

What I found in my case was that the top of the 8-inch pier was not completely flat. When assembling the mount I noticed a distinct wobble when I placed the base of the 1100 mount onto the top of the pier. I found that the top of the pier tube was not flat, and that the machined base of the 1100 mount was only making contact with the top of the pier in two places. I estimated that the base of the mount was tilting as much as 0.035". I could tighten the bolts holding the base of the mount onto the pier, but this was not enough to keep the assembled mount with the scope and counterweights from shifting under a load.

The solution was pretty simple. I coated the top of the pier with layout dye, placed the base of the mount on the pier, rotated it back and forth slightly, then removed the mount base. The high spots showed up as spots on the top of the pier where the dye had rubbed off. Using a file, I carefully filed the high spots (light and gentle touch on aluminum !!), recoated the top of the pier with layout dye, and repeated the process. It took about 45 minutes to get the base of the mount making uniform contact completely around the top of the pier. After doing this the episodes of shifting polar alignment stopped. 

I have long suspected that another potential source of polar shifting is due to the generous clearance between the bolt holes on the top of the pier and the 5/16-18 bolts that are used to attach the base of the mount to the pier. As long as the load is centered over the base of the mount, the assembled mount with scope and counterweights is is not likely to shift, but I think it would be better to have some alignment pins that positively lock the top of the pier and mount base in position. The current configuration of the 1100 mount uses six bolts to attach the base of the mount to the pier. I would like to see three of the bolts replaced with tapered dowel pins. This would provide a rock solid connection of the mount base to the pier that will not shift (assuming the top of the pier is flat). The only problem with tapered dowel pins is that they can really get stuck. A method of removing them has to be devised, but I'll bet that Roland's outstanding machinist can devise a very clever way to do this.

I hope that this helps. Good luck in solving your problem.


Re: Mach 1 Milestone – GearBox

Roland Christen
 

You can use the clutches on the older style. Just loosen the knobs 4 to 6 turns until they are very loose. You can then get a good feel for the balance. In fact, with the 1100 mount and the older non-spring gearboxes you really don't need to balance all that critically. With the new spring gearbox, the balance is more critical because you want to make sure that the teeth are fully meshed. I can get the 1100 mount to track just as accurately with the non-spring gearbox unbalanced as the new spring loaded gearbox fully balanced.

Rolando



-----Original Message-----
From: Dale Ghent daleg@... [ap-gto]
To: ap-gto
Sent: Tue, Aug 21, 2018 6:33 pm
Subject: Re: [ap-gto] Mach 1 Milestone – GearBox


Man, I really hope these new boxes get issued as a retrofit. I've never used the new boxes but it sounds like they would be a godsend to us mobile users.


> On Aug 21, 2018, at 5:14 PM, Ron Kramer ronkramer1957@... [ap-gto] gto@...> wrote:
>
>
>
> Nothing to it and a great feature. I use them all the time in place of clutches. I RARELY loosen or tighten the clutches.
>
>
> On Tue, Aug 14, 2018 at 8:21 PM darrellx@... [ap-gto] gto@...> wrote:
>
> Hi All
>
>
>
> Tonight, I achieved another milestone with the Mach 1. I used the Lever Assembly and disengaged the Worm Wheel for fine balancing.
>
>
>
> It has taken a while for me to work up the courage for this. The thought of it was quite daunting.
>
>
>
> However, now that I have done it – EASY AS! Nothing to it. Its a brilliant system.
>
>
>
> I realise I have not posed a question or raised a problem. I hope it is not an issue posting my “successes” here.
>
>
>
> Thanks
>
>
> Darrell
>
>
>
>
>
>
>



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Posted by: Dale Ghent <daleg@...>
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Re: Mach 1 Milestone – GearBox

Dale Ghent
 

Man, I really hope these new boxes get issued as a retrofit. I've never used the new boxes but it sounds like they would be a godsend to us mobile users.

On Aug 21, 2018, at 5:14 PM, Ron Kramer ronkramer1957@... [ap-gto] <ap-gto@...> wrote:



Nothing to it and a great feature. I use them all the time in place of clutches. I RARELY loosen or tighten the clutches.


On Tue, Aug 14, 2018 at 8:21 PM darrellx@... [ap-gto] <ap-gto@...> wrote:

Hi All



Tonight, I achieved another milestone with the Mach 1. I used the Lever Assembly and disengaged the Worm Wheel for fine balancing.



It has taken a while for me to work up the courage for this. The thought of it was quite daunting.



However, now that I have done it – EASY AS! Nothing to it. Its a brilliant system.



I realise I have not posed a question or raised a problem. I hope it is not an issue posting my “successes” here.



Thanks


Darrell







Re: Mach 1 Milestone – GearBox

Ron Kramer
 

Nothing to it and a great feature. I use them all the time in place of clutches. I RARELY loosen or tighten the clutches. 


On Tue, Aug 14, 2018 at 8:21 PM darrellx@... [ap-gto] <ap-gto@...> wrote:
 

Hi All


Tonight, I achieved another milestone with the Mach 1.  I used the Lever Assembly and disengaged the Worm Wheel for fine balancing.


It has taken a while for me to work up the courage for this.  The thought of it was quite daunting.


However, now that I have done it – EASY AS!  Nothing to it.  Its a brilliant system.


I realise I have not posed a question or raised a problem.  I hope it is not an issue posting my “successes” here.


Thanks

Darrell



Re: Mach1 and PEMPro

Roland Christen
 

Hey cool!

Rolando



-----Original Message-----
From: privatekey42@... [ap-gto]
To: ap-gto
Sent: Tue, Aug 21, 2018 6:46 am
Subject: [ap-gto] Mach1 and PEMPro



I've just been trying out PEMPro on my new Mach1 and I must say that I'm impressed … both by PEMPro and the mount!

There are two images of curves in the folder "Mach1 PEC test" on this Yahoo group - one with PEM off for measuring the raw PE and one with PEM on after the computed curve was uploaded to the mount.

Peak to peak error was 3.8 arcseconds for the raw PE and only 0.78 seconds with PEM on!

Thanks AP (and CCDWare)  - very nice! 

Paul



Re: New file uploaded to ap-gto

Roland Christen
 

Sure,

All I do is watch the drift when doing a PEMPro run. The idea is to adjust the altitude axis slightly up or down until the drift zeros out. Each worm cycle takes about 6.4 minutes, and the position of the star is sampled every second or so. Once you have created and downloaded a good PE curve and turned PEM on, then theoretically you should get a straight line without the up and down motion of periodic error. You can see within 1 minute whether that straight line heads high (star drifting West) or lower (star drifting East) and make a small adjustment to the altitude axis.

I would do these kinds of adjustments on hazy nights when the air is steady and imaging is not going to be good, on a mount that is permanently set up. It's not something that I would do with a portable setup. You don't need to get that fancy with perfect polar alignment on a portable rig since you will be guiding anyway and not want to waste precious clear skies for imaging.

Rolando



-----Original Message-----
From: tom.haugh@... [ap-gto]
To: ap-gto
Sent: Mon, Aug 20, 2018 10:01 pm
Subject: Re: [ap-gto] New file uploaded to ap-gto



Roland,

Can you elaborate on your PemPro curve RA adjustment procedure?

Tom Haugh
Pear Tree Observatory
IAU H23


Re: New file uploaded to ap-gto

Roland Christen
 


Still waiting on fix for wireless dropping its connection though.
One of the things our electronic engineer is working on.

Rolando


-----Original Message-----
From: biker123@... [ap-gto]
To: ap-gto
Sent: Mon, Aug 20, 2018 9:31 pm
Subject: Re: [ap-gto] New file uploaded to ap-gto



Roland,
I own both a 900 CP3 and a new 1100 CP4. And my club has a 1200 CP3.  I agree with your comments re: the performance of the 1100 mount. Plus the new features are big improvements.....having the Azimuth knobs on the South side of the scope makes it an easier reach with my 6" refractor....and the new clutches that can be disengaged make it much easier to balance the scope.  Still love the 900 but the 1100 is a huge improvement in many ways.
Still waiting on fix for wireless dropping its connection though....  ;-)     I am using a SkyFi which works perfectly so can wait until you get it figured out.



Re: New file uploaded to ap-gto

George
 

Tom,

 

See our Tech Support page:

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

 

Regards,

 

George

 

George Whitney

Astro-Physics, Inc.

Phone:  815-282-1513

Email:  george@...

 

From: ap-gto@... [mailto:ap-gto@...]
Sent: Monday, August 20, 2018 10:01 PM
To: ap-gto@...
Subject: Re: [ap-gto] New file uploaded to ap-gto

 

 

Roland,

 

Can you elaborate on your PemPro curve RA adjustment procedure?

 

Tom Haugh

Pear Tree Observatory

IAU H23

 


Mach1 and PEMPro

Paul
 

I've just been trying out PEMPro on my new Mach1 and I must say that I'm impressed … both by PEMPro and the mount!

There are two images of curves in the folder "Mach1 PEC test" on this Yahoo group - one with PEM off for measuring the raw PE and one with PEM on after the computed curve was uploaded to the mount.

Peak to peak error was 3.8 arcseconds for the raw PE and only 0.78 seconds with PEM on!

Thanks AP (and CCDWare)  - very nice! 

Paul


Re: New file uploaded to ap-gto

Thomas Haugh
 

Roland,

Can you elaborate on your PemPro curve RA adjustment procedure?

Tom Haugh
Pear Tree Observatory
IAU H23


Re: New file uploaded to ap-gto

Robert Berta
 

Roland,
I own both a 900 CP3 and a new 1100 CP4. And my club has a 1200 CP3.  I agree with your comments re: the performance of the 1100 mount. Plus the new features are big improvements.....having the Azimuth knobs on the South side of the scope makes it an easier reach with my 6" refractor....and the new clutches that can be disengaged make it much easier to balance the scope.  Still love the 900 but the 1100 is a huge improvement in many ways.
Still waiting on fix for wireless dropping its connection though....  ;-)     I am using a SkyFi which works perfectly so can wait until you get it figured out.


Re: New file uploaded to ap-gto

Roland Christen
 

For those who hate the files section, I have also posted it here on Facebook:

https://www.facebook.com/AstroPhysicsCorp/photos/a.773726079467391/1044748629031800/?type=3&theater

Rolando

-----Original Message-----
From: chris1011@... [ap-gto]
To: ap-gto ; ap-ug
Sent: Mon, Aug 20, 2018 5:47 pm
Subject: Re: [ap-gto] New file uploaded to ap-gto



Hi Astronuts,
 
My recent testing of mounts included an 1100 mount set up with my 130 EDX refractor and the analysis software PEMPro. Our runs of the 1100 mount have been very consistent with low periodic error and excellent repeatability. I wanted to do a real-life test on the night sky here at the observatory and show you the results.
 
The mount's raw periodic error measured at around 3.5 arc seconds on a night of medium seeing conditions. I ran 5 worm cycles due to the seeing being not great and created a PE curve that was then downloaded into the CP4 controller as the picture shows. The curve was run again with PE correction turned on and the result was less than 1 arc second. Analysis showed that the original curve put a 2nd harmonic into the PE playback, so I refined the curve by subtracting the second curve from the first and loaded the result into the CP4. PEMPro saves all the curves, so if you make a mistake, you don't need to start all over again.
 
The final result was a periodic error of 0.5 arc seconds, and at that point I felt it was good enough for a test run. I ran the mount for several 30 minute unguided test runs and had results of 1 arc sec or less in tracking error. This was done near the meridian and high enough so that atmospheric refraction was not an issue. I also made sure that the polar alignment was adjusted to zero out RA drift, something I did very simply by watching the curves in PEMPro and adjusting the altitude axis accordingly.
 
I feel that this is quite doable for the 1100 non-encoder mount and shows the level of performance you can achieve with this premium product. PEMPro comes with the 1100 mount, and it really works. It is not difficult at all to use and is very accurate. Just follow instructions ;^))
 
Roland

P.S.  the 1100 mount really is the Cat's meow and a bargain considering what level of performance, usability, portability and overall quality you are getting. There are many 900/1200 mounts out there still in use after 20 years and this mount beats them both.


-----Original Message-----
From: ap-gto gto@...>
To: ap-gto gto@...>
Sent: Mon, Aug 20, 2018 5:40 pm
Subject: [ap-gto] New file uploaded to ap-gto

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the ap-gto
group.

File : /1100 Periodic error testing/8-14-2018_1100_PemproRunSm.jpg
Uploaded by : uncarollo2 <chris1011@...>
Description : Measuring and refining periodic error using PEMPro

You can access this file at the URL:
https://groups.yahoo.com/neo/groups/ap-gto/files/1100%20Periodic%20error%20testing/8-14-2018_1100_PemproRunSm.jpg

To learn more about file sharing for your group, please visit:
https://help.yahoo.com/kb/index?page=content&y=PROD_GRPS&locale=en_US&id=SLN15398

Regards,

uncarollo2 <chris1011@...>


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Re: New file uploaded to ap-gto

Roland Christen
 

Hi Astronuts,
 
My recent testing of mounts included an 1100 mount set up with my 130 EDX refractor and the analysis software PEMPro. Our runs of the 1100 mount have been very consistent with low periodic error and excellent repeatability. I wanted to do a real-life test on the night sky here at the observatory and show you the results.
 
The mount's raw periodic error measured at around 3.5 arc seconds on a night of medium seeing conditions. I ran 5 worm cycles due to the seeing being not great and created a PE curve that was then downloaded into the CP4 controller as the picture shows. The curve was run again with PE correction turned on and the result was less than 1 arc second. Analysis showed that the original curve put a 2nd harmonic into the PE playback, so I refined the curve by subtracting the second curve from the first and loaded the result into the CP4. PEMPro saves all the curves, so if you make a mistake, you don't need to start all over again.
 
The final result was a periodic error of 0.5 arc seconds, and at that point I felt it was good enough for a test run. I ran the mount for several 30 minute unguided test runs and had results of 1 arc sec or less in tracking error. This was done near the meridian and high enough so that atmospheric refraction was not an issue. I also made sure that the polar alignment was adjusted to zero out RA drift, something I did very simply by watching the curves in PEMPro and adjusting the altitude axis accordingly.
 
I feel that this is quite doable for the 1100 non-encoder mount and shows the level of performance you can achieve with this premium product. PEMPro comes with the 1100 mount, and it really works. It is not difficult at all to use and is very accurate. Just follow instructions ;^))
 
Roland

P.S.  the 1100 mount really is the Cat's meow and a bargain considering what level of performance, usability, portability and overall quality you are getting. There are many 900/1200 mounts out there still in use after 20 years and this mount beats them both.


-----Original Message-----
From: ap-gto
To: ap-gto
Sent: Mon, Aug 20, 2018 5:40 pm
Subject: [ap-gto] New file uploaded to ap-gto

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the ap-gto
group.

File : /1100 Periodic error testing/8-14-2018_1100_PemproRunSm.jpg
Uploaded by : uncarollo2 <chris1011@...>
Description : Measuring and refining periodic error using PEMPro

You can access this file at the URL:
https://groups.yahoo.com/neo/groups/ap-gto/files/1100%20Periodic%20error%20testing/8-14-2018_1100_PemproRunSm.jpg

To learn more about file sharing for your group, please visit:
https://help.yahoo.com/kb/index?page=content&y=PROD_GRPS&locale=en_US&id=SLN15398

Regards,

uncarollo2 <chris1011@...>


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New file uploaded to ap-gto

ap-gto@...
 

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the ap-gto
group.

File : /1100 Periodic error testing/8-14-2018_1100_PemproRunSm.jpg
Uploaded by : uncarollo2 <chris1011@...>
Description : Measuring and refining periodic error using PEMPro

You can access this file at the URL:
https://groups.yahoo.com/neo/groups/ap-gto/files/1100%20Periodic%20error%20testing/8-14-2018_1100_PemproRunSm.jpg

To learn more about file sharing for your group, please visit:
https://help.yahoo.com/kb/index?page=content&y=PROD_GRPS&locale=en_US&id=SLN15398

Regards,

uncarollo2 <chris1011@...>


Re: Triplet Lens -vs- Doublet Lens

acf900gto@...
 

Rolando:

Thanks for the clarification on the differences between a triplet and doublet refractor related to narrow band imaging.  I have been able to find several sample images taken in NB using doublet refractors and some were very good.   So, good to know that a well made doublet would work as a good NB imaging platform -- especially if used in conjunction with a reducer / flatener.  

Charlie


---In ap-gto@..., <chris1011@...> wrote :



It is likely a triplet does a better job of correcting field curvature and other off axis issues but enough to count it out?
Filed curvature is a function of the focal length and has nothing to do with the number of elements if they are all in the same place up front. Typically the field curvature is around 1/3 of the focal length. There is also off-axis astigmatism which is similar in triplets and doublets. The only way around those two aberrations is to use a field flattener.

Rolando


-----Original Message-----
From: acf900gto@... [ap-gto] <ap-gto@...>
To: ap-gto <ap-gto@...>
Sent: Fri, Aug 17, 2018 5:56 pm
Subject: Re: [ap-gto] Triplet Lens -vs- Doublet Lens



The S2 and O3 filters would behave the same as the Ha.  Each would focus at a slightly different point but that happens anyway.   I believe the pixel scale would have an infinitesimal difference between the three masters.

I was specifically looking at a particular 152mm f/7.9 ED doublet as the basis for building a new scope.  Based on some of the published ray trace diagrams for lenses at this size and f/ratio, the RGB focuses are separated by about 1 mm.  This means you have a focal variation of 1mm in a 1200mm focal length.  I see a lot more focus spread than that from temperature variations when imaging with my 130mm f/6 APO.

Since a 152mm ED doublet lens is about $2,000 and a 152 ED triplet is about $6,000, it made me think about the real benefit of the triplet when considering NB imaging.  

It is likely a triplet does a better job of correcting field curvature and other off axis issues but enough to count it out?

With RGB imaging, the filter band passes are way bigger.  Probably enough to show problems but in NB, maybe not.  I guess all this could be tried with a smaller ED doublet refractor but I know there are optical engineers out there and was hoping for some feed back on the idea.  Or even info and pix from someone already doing this.

Charlie

 



Re: Some doubts about the use of the clutch knobs on the Mach1

Marcelo Figueroa
 

Thank you Roland, thank you all.


Re: 1100GTO not holding polar alignment

Roland Christen
 

Yes, I realize that. That is why I suggested the following:

Then tighten things down and slew the RA and Dec axes around and watch Polaris to see if it changes position on the circle. If it moves around, then you can start looking to see what is moving. Start from the earth-tripod connection and work your way up.

Only you can determine what's moving, the rest of us are too far away to see anything.

Rolando



-----Original Message-----
From: Joe Renzetti axnyslie@... [ap-gto]
To: ap-gto
Sent: Mon, Aug 20, 2018 12:16 pm
Subject: Re: [ap-gto] 1100GTO not holding polar alignment



I have been doing exactly that and Polaris is quite noticeably moving off of the spot where the NCP is. I usually have to reset it after the DSO target has been centered up and ready to image.

Joe

On Mon, Aug 20, 2018 at 12:33 PM, chris1011@... [ap-gto] <ap-gto@...> wrote:
 

the 1100 suddenly not holding
How are you determining that the 1100 is not holding? Holding what?

Having the RAPAS not perfectly aligned is not a problem if you want to find out if the Polar Axis is moving around or not. Just simply aim the RAPAS to the NCP, adjust the alt and az until Polaris is on the circle where it's supposed to be. Then tighten things down and slew the RA and Dec axes around and watch Polaris to see if it changes position on the circle. If it moves around, then you can start looking to see what is moving. Start from the earth-tripod connection and work your way up. If Polaris doesn't move around, then your mount/tripod is not changing and there is no issue.

Rolando


-----Original Message-----
From: Joe Renzetti axnyslie@... [ap-gto] <ap-gto@...>
To: ap-gto <ap-gto@...>
Sent: Mon, Aug 20, 2018 11:06 am
Subject: Re: [ap-gto] 1100GTO not holding polar alignment



Thanks for the info. Yes I did align the RAPAS with the set screws as it was really off when it got it (used mount). I used a PoleMaster and redid the routine twice to confirm. But I wonder now if it is still off. When I say centering Polaris I mean I am using Polaris to check if RAPAS is aligned with the RA axis of the 1100, not doing an actual polar alignment. On my pervious iOptron mount I aligned the polar scope by centering a flag pole top in the scope, then move the RA axis East & West and adjust until there's no movement from the center. As it is now Polaris moves a bit off center in the RAPAS when I do the same check. For now I'm going to really tighten down the HD tripod as that really seems more the culprit rather than the 1100 suddenly not holding as it did really well for the first few months.

Joe

On Mon, Aug 20, 2018 at 11:41 AM, 'Joseph Zeglinski' J.Zeglinski@... [ap-gto] <ap-gto@...> wrote:
 
Joe,
 
    Just to confirm, since you use the RAPAS for polar alignment, did you ... perform the alignment of the RAPAS device, adjusting its three set screws, after doing a precise PemPro polar align first?
You cannot rely on the RAPAS factory settings – with the exception of only the AP-900 mount.
 
    Once itself aligned, the RAPAS can then be relied upon for decent accuracy in future setups of that mount thereafter, but not before.
 
Joe Z.







Re: 1100GTO not holding polar alignment

Dale Ghent
 

A suggestion is to use a string coated in some power - talc, chalk, whatever, and snap it or wrap it around the tripod legs where they telescope. The resulting line should be fine enough to inform you if there is creeping going on there in case it subducts into the piece above it. I had the original Losmandy HD tripod and after a few years one of its legs became anemic despite how hard I cranked the thing down. You can then wipe the chalk line off when you think you're done with it.

/dale

On Aug 20, 2018, at 6:44 AM, Joe Renzetti axnyslie@... [ap-gto] <ap-gto@...> wrote:



Thanks I will give a thorough examination to the Losmandy tripod and see is anything is moving. I'm always on pavement but usually extending one or two legs slightly to level the mount. The camera when attached to the Hyperstar is very stable I never have issues there. I'm still not sure if the RAPAS is aligned correctly. I've used the Polemaster a couple times and it's usually where it's aligned now. I wonder if it may be better to do the daytime flagpole alignment. I centered it on Polaris and when I moved the mount to Park 1 position Polaris moved off center slightly.

Joe

On Mon, Aug 20, 2018 at 2:35 AM, 'Joseph Zeglinski' J.Zeglinski@... [ap-gto] <ap-gto@...> wrote:

Joe,

One other check – the Losmandy HD tripod head has “L-shaped slots“ for the LT2APM adapter’s three mount attachment screws. Make sure that you give the seated mount a hard twist to lock it in, after you drop it into the tripod, so that the three screws have slid to their extreme horizontal positions inside the three horizontal slot sections – and are not just sitting right under the insertion drop-in point (i.e. the vertical slot). Otherwise, the mount could shift up & down on one side, with slight changes in weight distribution during slews.

If you haven’t done so, buy a set of those Losmandy Tripod Knobs (AP # LTKS) for the pier – they have a wider diameter grip surface onto the HD slot holes than AP’s screw heads, easier to tighten in the field, even with an Allan wrench (in later versions), if needed, than the usual AP mount’s base screws which required a much thinner Allen wrench.

When I used my AP-900, carrying it to a field portable setup each time, setup was so much easier and quicker, if I left those three LTKS knobs “well-loosened”, but still attached to the LT2APM. Didn’t need to keep threading in these tripod knobs every time - or worse, losing those original small AP mount base ring screws that they replaced.

Joe Z.