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Re: Debugging Dec failure to move w/1200 CP3
Thanks Rolando. Good to know. So much for that test....I'll order a new cable. I decided to not start taking things apart until I've done that check. Steve
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Re: New AP1100, indoor practice, lots of little questions
Roland Christen
- I remain baffled by the whole concept of home, find home, Homing is only needed if you do an improper sync/recal on a wrong object and thus get the mount lost. For instance, if you put Vega in the center of your field but sync on Deneb, then you have told the mount a lie and it will be lost for any subsequent slews. each slew depends on the last position. If you get the mount lost, simply send it Home. It will go to the park3 position and recalibrate itself.
There is one caveat. This only works if you operate the mount in clutchless mode (never loosening the clutches and moving it manually). If you do decide to use the clutches, you can re-establish Home by manually moving the mount to Park3 positions and then sending a command to establish this as Home. Home can be established using APCC. Or you can enter the "set home command" manually.
Rolando
-----Original Message-----
From: ap@... <ap@...> To: main@ap-gto.groups.io Sent: Sat, Jul 31, 2021 3:46 pm Subject: [ap-gto] New AP1100, indoor practice, lots of little questions Still haven't gotten it outside. Tonight looks iffy. Testing indoors, some questions if someone has patience with a newbie:
- I remain baffled by the whole concept of home, find home, "correctly calibrated with the sky" (for 3D view). If I unpark from a known position, I apparently am not calibrated? Or does it need at least one plate solve and sync? And most advice about AE seems to be "leave it turned on, done". But what's the whole "FIND HOME" for, which seems to require a Configure home, which seems to require an APPM run. So do I need an APPM model for AE's? Or maybe more basically what's Find Home for, and do I need it? (On advice of another I was just ignoring APPM for now). I should note that the 3D view frequently comes up wildly wrong, even though everything else looks perfect, so I think I am doing something wrong in this regard. (I just read the APCC manual a 2nd time, and this aspect and AE differences is still opaque to me). - I looked with pempro and there is a PE curve loaded. This is an AE mount. I have PEM off (based on the label). Is that right, that the curve is there only if you turn off the AE's? - I loaded a custom horizon (had one in TSX) and that worked fine, but it doesn't seem associated with the site. Am I understanding correctly, you need to manage horizons separately from sites? - The ASCOM V2 "configure now" button seems to take all your changes including current site into the (apparently otherwise independent) driver info like site. It is not taking elevation, it leaves it unchanged. Small bug? Doesn't matter for me, I live in Flatland, everything's basically zero. Unless I'm doing something more fundamental wrong? My thinking is that basically you set everything in APCC and never in the ASCOM driver itself, it just flows from APCC, is that right in general? On the good side, I set up for a realistic meridian flip in NINA using a daytime target, and it counted down, flipped perfectly on the first try. I'm loving how things just plain work, and yes, I'm probably overthinking some of these things (again), but you know -- cloudy nights, got to do something. I've re-dressed the cables on the tripod now until they are way too pretty. :) If the clouds continue I may have to start polishing the counterweights. :( Linwood -- Roland Christen Astro-Physics
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Re: New AP1100, indoor practice, lots of little questions
ap@CaptivePhotons.com
How is that different from just parking to a known park position and unparking?
So my main reason for getting encoders was to better battle wind – during dry season here, it is often more windy, and I was losing lots of subs as the wind went from, say, 3mph to 8mph. I know there’s no complete solution for wind, but I understood AE’s would help a lot. Hope that’s true?
OK. Agreed. But does that affect how they work for wind?
I don’t understand how the mount can slew to the right position in the sky (in daylight, so “right” here means “by eye right direction”) but the 3D model shows it grossly off, maybe even upside down type wrong. The good news is the mount is right, I just don’t know where I’m going wrong to confuse the 3D model.
When I say “slew to the right position” I mean I use NINA, pick a star that’s high in daylight, and do a slew. The mount looks like it is in the right position and pointing to where the star would be. Clearly it has not been sync’d to a plate solve.
Linwood
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Re: New AP1100, indoor practice, lots of little questions
Bill Long
Homing returns the mount to a known position in the event it gets lost. IIRC it also clears any recent recal data. You can set the home position as you see fit (I use park 3) and if the mount ever gets lost for whatever reason you can press home and it
will return to that position (park 3 in my case).
The encoders are best suited to having the model running, but technically speaking they will still function without it. This is where he users get confused. Models are NOT only useful for observatories. Smaller models can be used quite effectively for
the backyard or mobile imager. For a single night of imaging I probably wouldn't build one, but for anything more than one night, I do. Getting APPM runs comfortably into your workflow will only help you get the most out of your investment.
If you're properly PA'd and recal with solving (APPM is configured to do this for you by default) the 3D model should work perfectly fine.
PEM is not used with encoders but if you had them off for whatever reason you would want a curve. That's nice they still build you a factory one! Those curves are quite good.
I ignore the v2 driver after having APCC configure it. APCC is the master, and as long as everything is properly setup in APCC it really shouldn't matter since the v2 driver sends everything through APCC.
If you get bored, you can install sky safari on your mobile and connect that to the mount over wifi and play with that.
From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of ap@... <ap@...>
Sent: Saturday, July 31, 2021 1:46 PM To: main@ap-gto.groups.io <main@ap-gto.groups.io> Subject: [ap-gto] New AP1100, indoor practice, lots of little questions Still haven't gotten it outside. Tonight looks iffy. Testing indoors, some questions if someone has patience with a newbie:
- I remain baffled by the whole concept of home, find home, "correctly calibrated with the sky" (for 3D view). If I unpark from a known position, I apparently am not calibrated? Or does it need at least one plate solve and sync? And most advice about AE seems to be "leave it turned on, done". But what's the whole "FIND HOME" for, which seems to require a Configure home, which seems to require an APPM run. So do I need an APPM model for AE's? Or maybe more basically what's Find Home for, and do I need it? (On advice of another I was just ignoring APPM for now). I should note that the 3D view frequently comes up wildly wrong, even though everything else looks perfect, so I think I am doing something wrong in this regard. (I just read the APCC manual a 2nd time, and this aspect and AE differences is still opaque to me). - I looked with pempro and there is a PE curve loaded. This is an AE mount. I have PEM off (based on the label). Is that right, that the curve is there only if you turn off the AE's? - I loaded a custom horizon (had one in TSX) and that worked fine, but it doesn't seem associated with the site. Am I understanding correctly, you need to manage horizons separately from sites? - The ASCOM V2 "configure now" button seems to take all your changes including current site into the (apparently otherwise independent) driver info like site. It is not taking elevation, it leaves it unchanged. Small bug? Doesn't matter for me, I live in Flatland, everything's basically zero. Unless I'm doing something more fundamental wrong? My thinking is that basically you set everything in APCC and never in the ASCOM driver itself, it just flows from APCC, is that right in general? On the good side, I set up for a realistic meridian flip in NINA using a daytime target, and it counted down, flipped perfectly on the first try. I'm loving how things just plain work, and yes, I'm probably overthinking some of these things (again), but you know -- cloudy nights, got to do something. I've re-dressed the cables on the tripod now until they are way too pretty. :) If the clouds continue I may have to start polishing the counterweights. :( Linwood
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New AP1100, indoor practice, lots of little questions
ap@CaptivePhotons.com
Still haven't gotten it outside. Tonight looks iffy. Testing indoors, some questions if someone has patience with a newbie:
- I remain baffled by the whole concept of home, find home, "correctly calibrated with the sky" (for 3D view). If I unpark from a known position, I apparently am not calibrated? Or does it need at least one plate solve and sync? And most advice about AE seems to be "leave it turned on, done". But what's the whole "FIND HOME" for, which seems to require a Configure home, which seems to require an APPM run. So do I need an APPM model for AE's? Or maybe more basically what's Find Home for, and do I need it? (On advice of another I was just ignoring APPM for now). I should note that the 3D view frequently comes up wildly wrong, even though everything else looks perfect, so I think I am doing something wrong in this regard. (I just read the APCC manual a 2nd time, and this aspect and AE differences is still opaque to me). - I looked with pempro and there is a PE curve loaded. This is an AE mount. I have PEM off (based on the label). Is that right, that the curve is there only if you turn off the AE's? - I loaded a custom horizon (had one in TSX) and that worked fine, but it doesn't seem associated with the site. Am I understanding correctly, you need to manage horizons separately from sites? - The ASCOM V2 "configure now" button seems to take all your changes including current site into the (apparently otherwise independent) driver info like site. It is not taking elevation, it leaves it unchanged. Small bug? Doesn't matter for me, I live in Flatland, everything's basically zero. Unless I'm doing something more fundamental wrong? My thinking is that basically you set everything in APCC and never in the ASCOM driver itself, it just flows from APCC, is that right in general? On the good side, I set up for a realistic meridian flip in NINA using a daytime target, and it counted down, flipped perfectly on the first try. I'm loving how things just plain work, and yes, I'm probably overthinking some of these things (again), but you know -- cloudy nights, got to do something. I've re-dressed the cables on the tripod now until they are way too pretty. :) If the clouds continue I may have to start polishing the counterweights. :( Linwood
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Re: 1100GTO AE PHD2 Settings
#Guiding
#Absolute_Encoders
Roland Christen
If the guiding is good, then that's all that matters. Perfect balance is not expected, just get it as close as you can.
Rolando
-----Original Message-----
From: Eric Dreher <ericpdreher@...> To: main@ap-gto.groups.io Sent: Sat, Jul 31, 2021 1:09 pm Subject: Re: [ap-gto] 1100GTO AE PHD2 Settings #Guiding #Absolute_Encoders #Guiding Roland, that begs the question about other models. With my 2017 Mach1GTO, I release the gearboxes, balancing RA as best I can, with DEC being a different animal. On Pier East, Dec is just about spot-on, while Pier West is camera-heavy. At times I do try to split the difference, but wonder if I'm really doing any good.
Last week's guiding had PHD2 RA at 0.25", Dec at 0.14", and an RMS of 0.28". It seems like it doesn't get much better. I'd appreciate your input, and thank you. -- Roland Christen Astro-Physics
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Re: 1100GTO AE PHD2 Settings
#Guiding
#Absolute_Encoders
Eric Dreher <ericpdreher@...>
Roland, that begs the question about other models. With my 2017 Mach1GTO, I release the gearboxes, balancing RA as best I can, with DEC being a different animal. On Pier East, Dec is just about spot-on, while Pier West is camera-heavy. At times I do try to split the difference, but wonder if I'm really doing any good.
Last week's guiding had PHD2 RA at 0.25", Dec at 0.14", and an RMS of 0.28". It seems like it doesn't get much better. I'd appreciate your input, and thank you.
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Re: 1100GTO AE PHD2 Settings
#Guiding
#Absolute_Encoders
Roland Christen
Even for non-encoder 1100 mounts you should balance both RA and Dec. No need for east heavy on RA. Both axes have spring loaded worm mesh, so you won't gain anything from unbalance. Dec unbalance will produce more delay in reversal due to higher static friction, so again it is best to balance the Dec axis well.
Rolando
-----Original Message-----
From: skester@... To: main@ap-gto.groups.io Sent: Sat, Jul 31, 2021 10:55 am Subject: Re: [ap-gto] 1100GTO AE PHD2 Settings #Guiding #Absolute_Encoders #Guiding Roland,
I have a non AE 1100GTO. Based on supposed 'best practices', I have always left a slight imbalance of East heavy in RA, and 'camera heavy' in Dec. However this practice was likely intended for mounts with considerably more backlash than an AP mount. If I'm interpreting your post correctly, Dec should be as close to perfectly balanced as possible. Does that hold for both AE and non-AE mounts? Also should I continue to use slightly East heavy in RA, or should that be as close to perfectly balanced as well? Thanks, Scott -- Roland Christen Astro-Physics
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Re: Debugging Dec failure to move w/1200 CP3
Roland Christen
Yeah, I would call it a dead cable since the RA went dead once you plugged the dec cable into it Wrong assumption unfortunately. Leaving the RA cable unplugged triggers a motor stall fault even in a good mount with a good cable.
Rolando
-----Original Message-----
From: Dale Ghent <daleg@...> To: main@ap-gto.groups.io Sent: Fri, Jul 30, 2021 10:38 pm Subject: Re: [ap-gto] Debugging Dec failure to move w/1200 CP3 Yeah, I would call it a dead cable since the RA went dead once you plugged the dec cable into it, so the problem followed it. It wouldn't surprise me for a such an old mount. I maintain a 1200GTO for my club and its Y cable's insulation feels stiff the touch and the jacket material appears to be quite oxidized, giving it an almost brittle look. I wouldn't be surprised if it threw in the towel at some point after nearly 20 years of hot summers and cold winters and flexing under use, assuming it's the original cable. Even though the performance of the mount is pretty much flawless, I should probably have the club get a spare to keep on hand.
> On Jul 30, 2021, at 23:29, Steven Panish <scpanish@...> wrote: > > Unfortunately the RA branch of the y-cable is too short to make it to the DEC motor connector. I may be able to pull off the CP3 and get the cable to connect to the DEC motor. I did put the DEC cable onto the RA and the motor did not come on. So that would support the idea that there is a fault in the cable or CP3. > > There is no visible corrosion on any of the connector pins. They do not appear to be gold plated, this is an old mount. I put DeOxIt on the female connector sockets. Didn't help. I'll open the CP3 up and see if any corrosion is visible. Seems unlikely, this is in an observatory, but NH does get humid. > > There are no software limits set that would do this. The problem appeared out of the blue. > > Guess I'll order a spare Y cable next week. > > Steve > > On Thu, Jul 29, 2021 at 4:06 PM Jeffc <jeffcrilly@...> wrote: > > >> On Jul 29, 2021, at 12:00 PM, Christopher Erickson <christopher.k.erickson@...> wrote: >> >> >> Also consider getting a spare motor Y-cable and try that. EVERYONE should have a spare motor Y-cable in their kit. A spare power cord too. > > Fwiw.. I also have a spare Y-cable for the 1200. > I broke the original cable once, and fixed it… but after that incident I decided to get a spare just in case. > >> >> And there is an outside chance that a software axis limit setting is involved. >> >> >> -Christopher Erickson >> Observatory engineer >> Waikoloa, HI 96738 >> www.summitkinetics.com >> >> >> On Thu, Jul 29, 2021, 11:50 AM Manusfisch via groups.io <tjfischer653=mac.com@groups.io> wrote: >> Wasn’t there a problem with the CP3 where the inside board became loose or had a corroded connection inside the box that might make intermittent problems come up with power to the motor or control to the motor? I don’t have a CP3 just a later model CP4 so I can’t really comment technically I just remember a conversation >> >> TJF Mobile >> >>> On Jul 29, 2021, at 08:18, Steven Panish <scpanish@...> wrote: >>> >>> >>> Eric, >>> The CP3 is connected through a serial/usb converter, but the RA still responds to a nudge even when the DEC does not, so the port is still alive. And the handbox shows the same issue. I think the fault has to be later in the path than the comm between the PC or handbox and the CP3. Although I don't know the architecture. Good thought though. >>> Steve >>> >>> >>> >>> On Thu, Jul 29, 2021 at 11:09 AM Eric Dreher <ericpdreher@...> wrote: >>> Some will sleep, removing power from the port when it's considered inactive. >>> >>> >> >> > > > -- Roland Christen Astro-Physics
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Re: Debugging Dec failure to move w/1200 CP3
Roland Christen
I did put the DEC cable onto the RA and the motor did not come on. If you don't plug the RA cable into one of the motor boxes, the CP3 will automatically assume a motor fault. You must plug the RA cable into the Dec motor box to get a valid result.
Rolando
-----Original Message-----
From: Steven Panish <scpanish@...> To: main@ap-gto.groups.io Sent: Fri, Jul 30, 2021 10:29 pm Subject: Re: [ap-gto] Debugging Dec failure to move w/1200 CP3 Unfortunately the RA branch of the y-cable is too short to make it to the DEC motor connector. I may be able to pull off the CP3 and get the cable to connect to the DEC motor. I did put the DEC cable onto the RA and the motor did not come on. So that would support the idea that there is a fault in the cable or CP3.
There is no visible corrosion on any of the connector pins. They do not appear to be gold plated, this is an old mount. I put DeOxIt on the female connector sockets. Didn't help. I'll open the CP3 up and see if any corrosion is visible. Seems unlikely, this is in an observatory, but NH does get humid.
There are no software limits set that would do this. The problem appeared out of the blue.
Guess I'll order a spare Y cable next week.
Steve
On Thu, Jul 29, 2021 at 4:06 PM Jeffc <jeffcrilly@...> wrote:
-- Roland Christen Astro-Physics
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Re: 1100GTO AE PHD2 Settings
#Guiding
#Absolute_Encoders
skester@...
Roland,
I have a non AE 1100GTO. Based on supposed 'best practices', I have always left a slight imbalance of East heavy in RA, and 'camera heavy' in Dec. However this practice was likely intended for mounts with considerably more backlash than an AP mount. If I'm interpreting your post correctly, Dec should be as close to perfectly balanced as possible. Does that hold for both AE and non-AE mounts? Also should I continue to use slightly East heavy in RA, or should that be as close to perfectly balanced as well? Thanks, Scott
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Re: Early Meridian Flip not completing
Ray Gralak
Hi Wayne,
Hi Ray, this is happening even when I’m just running APCC. The only change I remember making is enabling SafetyNo, that is not pertinent at all. But, what do you have set for the "Action when limit is reached" on APCC's Meridian tab? That should be set to "Just Warn". -Ray -----Original Message-----
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Re: Testing scopes and mounts - Imaging from Hawaii
R Botero
Roland
Great post and great trip! Roberto
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Re: Debugging Dec failure to move w/1200 CP3
Just like the Hubble. Need a backup! Don Anderson
On Friday, July 30, 2021, 09:39:00 p.m. MDT, Dale Ghent <daleg@...> wrote:
Yeah, I would call it a dead cable since the RA went dead once you plugged the dec cable into it, so the problem followed it. It wouldn't surprise me for a such an old mount. I maintain a 1200GTO for my club and its Y cable's insulation feels stiff the touch and the jacket material appears to be quite oxidized, giving it an almost brittle look. I wouldn't be surprised if it threw in the towel at some point after nearly 20 years of hot summers and cold winters and flexing under use, assuming it's the original cable. Even though the performance of the mount is pretty much flawless, I should probably have the club get a spare to keep on hand. > On Jul 30, 2021, at 23:29, Steven Panish <scpanish@...> wrote: > > Unfortunately the RA branch of the y-cable is too short to make it to the DEC motor connector. I may be able to pull off the CP3 and get the cable to connect to the DEC motor. I did put the DEC cable onto the RA and the motor did not come on. So that would support the idea that there is a fault in the cable or CP3. > > There is no visible corrosion on any of the connector pins. They do not appear to be gold plated, this is an old mount. I put DeOxIt on the female connector sockets. Didn't help. I'll open the CP3 up and see if any corrosion is visible. Seems unlikely, this is in an observatory, but NH does get humid. > > There are no software limits set that would do this. The problem appeared out of the blue. > > Guess I'll order a spare Y cable next week. > > Steve > > On Thu, Jul 29, 2021 at 4:06 PM Jeffc <jeffcrilly@...> wrote: > > >> On Jul 29, 2021, at 12:00 PM, Christopher Erickson <christopher.k.erickson@...> wrote: >> >> >> Also consider getting a spare motor Y-cable and try that. EVERYONE should have a spare motor Y-cable in their kit. A spare power cord too. > > Fwiw.. I also have a spare Y-cable for the 1200. > I broke the original cable once, and fixed it… but after that incident I decided to get a spare just in case. > >> >> And there is an outside chance that a software axis limit setting is involved. >> >> >> -Christopher Erickson >> Observatory engineer >> Waikoloa, HI 96738 >> www.summitkinetics.com >> >> >> On Thu, Jul 29, 2021, 11:50 AM Manusfisch via groups.io <tjfischer653=mac.com@groups.io> wrote: >> Wasn’t there a problem with the CP3 where the inside board became loose or had a corroded connection inside the box that might make intermittent problems come up with power to the motor or control to the motor? I don’t have a CP3 just a later model CP4 so I can’t really comment technically I just remember a conversation >> >> TJF Mobile >> >>> On Jul 29, 2021, at 08:18, Steven Panish <scpanish@...> wrote: >>> >>> >>> Eric, >>> The CP3 is connected through a serial/usb converter, but the RA still responds to a nudge even when the DEC does not, so the port is still alive. And the handbox shows the same issue. I think the fault has to be later in the path than the comm between the PC or handbox and the CP3. Although I don't know the architecture. Good thought though. >>> Steve >>> >>> >>> >>> On Thu, Jul 29, 2021 at 11:09 AM Eric Dreher <ericpdreher@...> wrote: >>> Some will sleep, removing power from the port when it's considered inactive. >>> >>> >> >> > > >
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Re: Debugging Dec failure to move w/1200 CP3
Dale Ghent
Yeah, I would call it a dead cable since the RA went dead once you plugged the dec cable into it, so the problem followed it. It wouldn't surprise me for a such an old mount. I maintain a 1200GTO for my club and its Y cable's insulation feels stiff the touch and the jacket material appears to be quite oxidized, giving it an almost brittle look. I wouldn't be surprised if it threw in the towel at some point after nearly 20 years of hot summers and cold winters and flexing under use, assuming it's the original cable. Even though the performance of the mount is pretty much flawless, I should probably have the club get a spare to keep on hand.
toggle quoted messageShow quoted text
On Jul 30, 2021, at 23:29, Steven Panish <scpanish@panishnet.com> wrote:
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Re: Debugging Dec failure to move w/1200 CP3
Unfortunately the RA branch of the y-cable is too short to make it to the DEC motor connector. I may be able to pull off the CP3 and get the cable to connect to the DEC motor. I did put the DEC cable onto the RA and the motor did not come on. So that would support the idea that there is a fault in the cable or CP3. There is no visible corrosion on any of the connector pins. They do not appear to be gold plated, this is an old mount. I put DeOxIt on the female connector sockets. Didn't help. I'll open the CP3 up and see if any corrosion is visible. Seems unlikely, this is in an observatory, but NH does get humid. There are no software limits set that would do this. The problem appeared out of the blue. Guess I'll order a spare Y cable next week. Steve
On Thu, Jul 29, 2021 at 4:06 PM Jeffc <jeffcrilly@...> wrote:
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Current manuals electronically?
ap@CaptivePhotons.com
Now that I got the AP1100 I realize the manuals I have are out of date. I almost never use paper, I vastly prefer electronic, I can read it on my phone, my kindle, my computer, etc.
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Testing scopes and mounts - Imaging from Hawaii
Roland Christen
Hi all,
Some musings from my weeks of testing in Hawaii:
I just got back from Hawaii where I was able to
spend a lot of time testing the guiding function of a 1600 encoder mount
with an AP 175mm refractor. The tests were performed under various
seeing conditions which ranged from 1.5 FWHM to 7.5 FWHM. Our
observatory is located on the west slope of Kohala mountain, which is on
the dry side of Hawaii Island.
The sharpest seeing occurred when the prevailing
winds came up-slope from the ocean or were parallel to the shoreline.
The worst came from trade winds that came over Kohala mountain and
curled overhead. The worst seeing was so bad that Saturn was
unrecognizable - it was just a boiling mess.
Over a period of 3 weeks I imaged just about every
night and gathered a lot of data - both image data and autoguiding data.
I also did a fair amount of unguided imaging. A couple of things stood
out immediately. No matter what settings of guide exposure, time lapse
and aggressiveness i used, the guiding results were almost 100%
dependent on seeing. If the seeing was poor, the guide results were the
same whether I used 2 second guide exposures or 10 second exposures.
Putting long delay between exposures also did not change the results. A
larger Min Move did help to prevent back and forth star chasing to some
extent when the seeing was bad. But no matter what, when the seeing was 5
arc sec FWHM the guiding was consistently around 0.6 arc sec rms. When
the seeing produced stars of 1.5 arc sec FWHM, the guiding at times went
below 0.1 rms. In other words the stars were twinkling slightly but
perfectly stationary and not doing the hula dance.
One thing i discovered was that for best guiding
results the axes should be very well balanced. The gear mesh release
mechanism of the 1600 gearbox allowed almost perfect balance with this
large refractor. It is much more critical to set the Dec balance
accurately than the RA axis. Reason is that unbalanced Dec causes static
friction in the worm gear teeth, which makes Dec movements non-linear
at the sub-arc sec level. The encoders do compensate and produce the
final position very accurately, but the static friction introduces delay
in getting there, overshoot, etc, which reduces the moment to moment
positional accuracy. Bottom line - balance Dec as close as possible. RA
is not affected by unbalance because it is always moving, so there is no
static friction to contend with. The only thing I noticed was an
increase in the sub-arc sec ripple in the sidereal drive rate. The more
balanced the axis, the smoother the RA tracking.
I accumulated on the order of 300 sub exposures of
the deep sky object that I was imaging (a mix of 10 minute and 20 minute
sub exposures). Out of these only about 5 had non-round stars due to an
occasional passing cloud. All stars were round, even when the seeing
was an astonishing and atrocious 7.5 arc seconds (seeing is a judge of
star size in FWHM, guiding is a judge of the guide star motions in arc
sec rms). So, even in poor seeing the dual encoders operated equally in
both axes to keep the scope pointed properly, even though the guide star
was pulsing like an amoeba. What might surprise long-time imagers is
that I plan to use very frame in the final image. I will not be throwing
out any of the subs, even though they contain bloated stars.
I did do some unguided imaging using the drift model
in the keypad. I was operating at approximately 1000mm focal length and
could do up to 20 minute subs with round stars. I used 8 points along
the object path, starting from 4 hours in the east with scope under the
mount, to 3 hours past the meridian in the west. The object was low
enough to the south to allow the scope to start underneath with
counterweight up. I experimented with a mix of unguided and nudge
guiding with very low aggression. The problem with low aggression is
when you are dithering it takes a long time for the guide star to come
back to zero. Same is true if you are using long exposure times or long
delay times between guide exposures. You have to allow for long guider
settling time, and that eats into your imaging time.
The scope itself performed beautifully with very
predictable focus with temperature. Even though the lens is a 175mm
triplet and the daytime observatory was between 95 - 98 degree F during
the day, once the roof was retracted and the sun set, the scope
acclimated within the hour to 75 degree air temp. It produced sharp
images as soon as it got dark enough to image. I refocused perhaps twice
or 3 times during the night until just before dawn when the temp
bottomed out at 68F. The nice thing about this triplet design was that
the focus did not change between all my narrowband filters.
For those who say that large airspaced triplet
lenses have long cooling/settling times, I did not experience that with
this scope. But then maybe my observing conditions are not as extreme as
some people experience? The AP 175 Triplet lens has thinner lens
elements than is normally used. This required a lot of careful polishing
at very low pressures when I fabricated them. And that cost a lot of
time and money, but the results are worth it. The lens is made with 2
elements of BSL7 and one with S-FPL53, both Ohara glasses and both
outstanding quality wise. Why is that important? Because what you get
with BSL7 is extremely high internal homogeneity. Some people are
enamored with Lanthanum mating elements, but these glass types were
never intended for objective grade lens applications and do not have the
high internal homogeneity of borosilicate crown glass. Lanthanum is
also much heavier and retains heat with longer thermal settling down
times.
Unfortunately S-FPL53 is no longer available but
fortunately FPL55 and Hoya FCD100 can be used with similar performance
using the same borosilicate crown mating elements.
I will do some more postings on mount and scope performance once I get a chance to analyze the data.
Rolando
-- Roland Christen Astro-Physics
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Re: Physical handling questions (AP1100)
Roland Christen
No need to unlock gear mesh or loosen clutches. Just leave it fully set up and go ahead and move it.
Roland
-----Original Message-----
From: ap@... <ap@...> To: main@ap-gto.groups.io <main@ap-gto.groups.io> Sent: Fri, Jul 30, 2021 6:44 pm Subject: Re: [ap-gto] Physical handling questions (AP1100) @Ken Kirkley wrote:
It wouldn’t be the first time. My only defense is that overthinking is usually better than under.
😊
That’s encouraging. Thank you.
@Ben Lutch
And do you just leave the gear mesh and clutches locked down? And thanks, good to know.
@Don Anderson
Excellent, I’m glad there seems to be an immediate consensus. Now can you guys just wish away the clouds that are forming.
😊
Thanks all.
Linwood
-- Roland Christen Astro-Physics
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Re: Physical handling questions (AP1100)
ap@CaptivePhotons.com
@Ken Kirkley wrote:
It wouldn’t be the first time. My only defense is that overthinking is usually better than under. 😊
That’s encouraging. Thank you.
@Ben Lutch
And do you just leave the gear mesh and clutches locked down? And thanks, good to know.
@Don Anderson
Excellent, I’m glad there seems to be an immediate consensus. Now can you guys just wish away the clouds that are forming. 😊
Thanks all.
Linwood
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