Go Back   IceInSpace > Equipment > Software and Computers

Reply
 
Thread Tools Rate Thread
  #1  
Old 15-04-2019, 08:41 AM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 3,342
Alternative to SGP, or just suck it up?

I have been using APT for imaging and for the most part I really like it. Almost everything I am trying to do with it goes very smoothly, it is easy to use and the developer is quite responsive (And is on this forum too)

The only chink in APT's armor as things stand (For me at least) is a current lack of automated focusing that works really well for my gear, and that can be periodically run unattended as part of an image plan. The C925 changes focus significantly with temperature changes. The OTA will contract by something in the order of 14 microns for a 1 degree change in temperature but the mirror configuration means that the focal plane will move by more like 350 microns. Well over double the size of the critical focus zone. Unless I want to sit up with it literally all night, intervening periodically in the focus then images end up disappointing.

I currently have SGP on the 45 day trial license, and it does manage focus quite well at least apparently. I have not had a full night chance to see what it will do over multiple images but it can fettle the focus well enough that a check with a Baht mask showed it to be nearly perfect. The issue with SPG is that IMO it is far harder to use than APT is. Particularly when it comes to plate solving and pointing control of the scope both for gross aiming and fine fettling of the aiming point. The big selling point (And it needs to be biggish due to the cost) is that it seems to cope with "Whole of image" focus of the SCT quite well, where single star focus is fraught. If sky conditions trick single star focus into running off the wrong way and the shadow of the secondary mirror becomes visible, the game is up!

Are there other options? or for the SCT do I just have to suck it up, pay the money and climb the learning curve? My 10 year old was able to start using APT with a little help from me, but I would not even point him at SGP.
Reply With Quote
  #2  
Old 15-04-2019, 09:22 AM
Camelopardalis's Avatar
Camelopardalis (Dunk)
Drifting from the pole

Camelopardalis is offline
 
Join Date: Feb 2013
Location: Brisbane
Posts: 5,425
It’s just a case of User Interface overload

It’s very target driven, and the whole sequence is multiple targets. Forgive me if I’m regurgitating the obvious.

What I found helpful was to open and arrange the docking modules that I wanted/needed so that I could easily access the functions I wanted without having to dig for them. There are a LOT of settings and functions, and the last thing you want to do on a clear night is to waste time looking for stuff!

SGP doesn’t have its own catalogue of objects, so can either Open an Image and solve that, or open the Sequence window, click on the cog for your target and enter rough RA and Dec there. You can Slew Now or Centre Now, the latter using plate solving to centre in on those coordinates.

With the plate solving, you can right click on an image and select Plate Solve. When you’ve got your target in the FOV, right click on what you want as field centre and select Centre Here. Then if you plate solve it once you’ve got the target where you want it, it’ll pop up a box offering to save it to your target.

Keep the Scope Centring docking module open, as that has the useful “Solve and Sync” function, which takes two button presses in APT. This is useful when you first go near your target.

Create your default equipment profile so that it’s used by all new sequences. You only need to do this once, rather than having to tweak all the settings every time - and there are a lot of them!

When it comes to the auto focus routine, the goal is to get a nice V-curve. Have the Focus Control docking module open. In Settings, set your Step Size to be whatever it would take to move through your critical focus zone (roughly). You’ll need to experiment to find the right Step Size, but the goal is to get a nice V-curve. If you’re seeing any coma or field curvature in your auto focus images, set the Auto Focus Crop By to something sensible. Ultimately, you want the stars in field centre to be sharp.

One thing to remember is that any settings you change “live” are not retained from one session to another. If you make changes and think “I’ve nailed it!”, remember to go into your Equipment Profile and make the changes there too.

Hope that helps...

They’re different tools for sure...I do still use APT regularly, with my Canon riding on a Star Adventurer, and it’s nice and simple
Reply With Quote
  #3  
Old 15-04-2019, 09:37 AM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 3,342
I am thinking that I might just have to suck it up and hit the learning curve. The "Killer" app within the app is in plan auto focus. I had that working pretty well after about an hours work the first night I used it, it is proving to be more or less essential for the SCT. It not only shifts with temp but a meridian flip moves it too, and the mirror only has to shift a couple of microns to blow focus out visibly. I did work out pretty quickly that if I made a change it was best to tweak it in the equipment profile then re apply that profile to the sequence.

I have not had enough time with it yet, can you readily load an image, plate solve it and then command a slew to the solved center? I had plate solving working both with plate solve 2 and with the local astrometry.net setup but the local astrometry.net one fell over about when I got focus working pretty nicely and it was about to cloud over so I just parked the mount and brought it in for the night.

I still reckon for my young bloke it will be vastly too complicated and I will leave him using APT, but he would be using the ED72 which is a lot more forgiving of focus so automation is not so essential.
Reply With Quote
  #4  
Old 15-04-2019, 09:50 AM
Camelopardalis's Avatar
Camelopardalis (Dunk)
Drifting from the pole

Camelopardalis is offline
 
Join Date: Feb 2013
Location: Brisbane
Posts: 5,425
Auto focus is pretty essential on a refractor too, especially as we go into winter.

Yeah you can go File then Open Image, select an image and then solve it. Plate Solve 2 usually needs a hint, so if you know it’s rough coordinates, enter them in the dialogue box. When prompted, save the coordinates to the target.

Alternatively, in the Target Settings (cog) there’s a link to Populate coordinates from Astrobin, etc.

Then you can right click on the target name and Centre.

Since SGP is meant to be largely unattended, you can check the boxes for Slew/Centre when target stars, and then it’ll go there automatically.

It might be something he will grow into, little ‘uns tend to be more tech literate than the generation before them
Reply With Quote
  #5  
Old 15-04-2019, 09:53 AM
Lognic04's Avatar
Lognic04 (Logan)
Registered User

Lognic04 is offline
 
Join Date: Mar 2016
Location: Melbourne, VIC
Posts: 889
Hi Paul,
you might be interested in trying NINA - It's a free open source alternative to SGP with identical functionality, but with much better dev support (hop on the discord if you have any issues). It runs everything in paralell (much faster than SGP!) and it also does AF identical to SGP, if not a bit faster too. The UI is far more intuitive too. I highly reccomend it! At the moment there are at least 100 people running NINA worldwide!

https://nighttime-imaging.eu/
Reply With Quote
  #6  
Old 15-04-2019, 10:12 AM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 3,342
I had seen that in the other thread but had not had any chance to look at it.

I will probably give SGP a bit more settling time first up to learn my way around it. Just aiming to make best use of the trial period to see what I like or do not like before I have to pay for it, given that the things I really need that APT can not do (At least currently) are only in the paid version.

Once that trial runs out I will look at NINA to compare. One learning curve at a time!

EDIT: One thing I could not see from the time I had to have a quick browse this morning, can you set focuser backlash settings external to the ASCOM driver? The for "inward" focus moves the SCT focuser needs a big backlash compensation, which is actually to combat the mirror flop that is inherent in the design. To make focus behave predictably I set both SGP and APT with a 500 step (Half a turn of the focuser shaft) "Backlash" compensation on inwards moves, so for instance moving from position 16,000 to 15,990 will be a move to 15,490 then back out to 15,990. The Celestron ASCOM driver at least currently is a bit basic and you can't set that up directly in the driver. If you don't do it the focusing results are spectacularly unreliable.
Reply With Quote
  #7  
Old 15-04-2019, 10:26 AM
Lognic04's Avatar
Lognic04 (Logan)
Registered User

Lognic04 is offline
 
Join Date: Mar 2016
Location: Melbourne, VIC
Posts: 889
NINA is free and very intuitive, so i hope you choose it!
Reply With Quote
  #8  
Old 15-04-2019, 10:27 AM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 3,342
One thing that APT is really handy fore that I am not sure you can readily do in SGP is an alignment plan. I t was dead simple to build a plan to automatically gather an N point alignment model for EQMOD.

"Unpark, move to position, blind sync-solve, move to new position, near sync-solve, move, near sync-solve" etc. In under ten minutes it would motor it's way around the sky, shoot, solve and sync a field of points for EQMOD and after that it would land targets pretty much perfectly centered all night.
Reply With Quote
  #9  
Old 15-04-2019, 10:27 AM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 3,342
One thing that APT is really handy for that I am not sure you can readily do in SGP is an alignment plan. It was dead simple to build a plan to automatically gather an N point alignment model for EQMOD.

"Unpark, move to position, blind sync-solve, move to new position, near sync-solve, move, near sync-solve" etc. In under ten minutes it would motor its way around the sky, shoot, solve and sync a field of points for EQMOD and after that it would land targets pretty much perfectly centered all night.
Reply With Quote
  #10  
Old 15-04-2019, 11:10 AM
ChrisV's Avatar
ChrisV (Chris)
Registered User

ChrisV is offline
 
Join Date: Aug 2015
Location: Sydney
Posts: 1,737
I'm like you Paul, I used APT for a fair while and year, love it and find it easy to use. Very intuitive. But I wanted something automated, especially since I made some stepper controllers for both my newt and refractor. And APT just doesn't do that, although I still use it when I go out to a dark site.

I shifted to SGPro in January. It has been a battle, but well worth it. I can just let it run all night and shut itself down before sunrise. I still have trouble with stuff in it. But its ability to frame targets (and mosaics which I haven't done yet), automate the night's session with meridian flips, focussing etc is brilliant. There was a big whingefest on cloudynights about problems with its automatic focussing - but I haven't had any issues (maybe I have a low threshold of acceptable focus). I just gets my flats at the start of the night, set the focus manually, then automated a few times and let it go. Trouble is the dog goes out to the verandah and has a leak on the tripod during the night

There is other automated software mentioned below, plus Voyager that Diego uses. But I went with SGPro; just because. I'm getting a lot more out of each night now. Just a matter of figuring out which software you prefer.
Reply With Quote
  #11  
Old 15-04-2019, 11:22 AM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 3,342
Hopefully the weather gods are nice to me and I can do some test runs over the next couple of weeks while the moon is up to try to get familiar with it. I ran the autofocus routine a number of times and found it to be landing within a handful of steps of the same place each time, with a small amount of drift that I put down to the tube cooling off. When I checked it with a Baht mask you would need to be pretty fussy to worry about it.

Mosaic framing is another thing, I seem to be gravitating toward doing things that will require mosaics. I saw an image on Facebook this morning taken with a DSLR and couldn't help myself but to check in Sky Safari and ended up thinking "Four panels would cover that nicely with the ED72"
Reply With Quote
  #12  
Old 15-04-2019, 11:22 AM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 3,342
Hopefully the weather gods are nice to me and I can do some test runs over the next couple of weeks while the moon is up to try to get familiar with it. I ran the autofocus routine a number of times and found it to be landing within a handful of steps of the same place each time, with a small amount of drift that I put down to the tube cooling off. When I checked it with a Baht mask you would need to be pretty fussy to worry about it.

Mosaic framing is another thing, I seem to be gravitating toward doing things that will require mosaics. I saw an image on Facebook this morning taken with a DSLR and couldn't help myself but to check in Sky Safari and ended up thinking "Four panels would cover that nicely with the ED72"

Pic of where the automated focus landed, checked with the mask.
Attached Thumbnails
Click for full-size image (64E96F3B-1047-4AF3-9A28-C44E36F4A2E7.jpeg)
124.7 KB68 views
Reply With Quote
  #13  
Old 15-04-2019, 01:52 PM
Camelopardalis's Avatar
Camelopardalis (Dunk)
Drifting from the pole

Camelopardalis is offline
 
Join Date: Feb 2013
Location: Brisbane
Posts: 5,425
Looks like pretty good focus to me

I’m not sure I understand the gist of the alignment plan surely if it’s plate solving to each target, it’s doing that as it goes along?
Reply With Quote
  #14  
Old 15-04-2019, 02:40 PM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 3,342
The alignment plan builds a pointing model in EQMOD. Essentially a single alignment point behaved like a single star alignment using the hand controller, with pointing accuracy falling off the further away from the sync point you are. Two sync points it chooses the nearest one and offsets from that. Three or more, if the target falls within the triangle made by three points is very much more accurate, if it is outside it goes back to the nearest point method. It allowed me to build up a web of align points so that anywhere I wanted to point falls between them (And they are ALT-AZ points not RA-DEC so they don't move with the sky) and it reliably landed anything I asked for almost perfectly in the middle of the chip.

Possibly better value in visual than imaging but I have had a tendency since starting the imaging to hunt around for targets during the night, looking for things that suit my framing to image properly later so it is handy to have what you asked for land right on the chip every time.

Plus it is cool watching it do its own thing aligning itself
Reply With Quote
  #15  
Old 15-04-2019, 04:12 PM
Lognic04's Avatar
Lognic04 (Logan)
Registered User

Lognic04 is offline
 
Join Date: Mar 2016
Location: Melbourne, VIC
Posts: 889
That's where programs like NINA and SGP come in handy
NINA especially has an object finder function and framing wizard!
Reply With Quote
  #16  
Old 15-04-2019, 04:40 PM
Karlzburg (Karl)
No moon for you!!

Karlzburg is offline
 
Join Date: Jun 2018
Location: Mudgee, NSW
Posts: 330
There is PRISM software as well, which does everything in one program. Mount control, focus control, plate solve, guide, star chart, image acquisition, image calibration, stacking and a lot more. I still need Star Tools for the final touch up.
It has a 80 day trial as well as youtube vids and forum to help.
Reply With Quote
  #17  
Old 15-04-2019, 04:50 PM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 3,342
Actually having just got home and checked something, SGP at least has a setting which will really help with autofocus on the SCT, the ability to reverse the in and out focuser moves will be a huge help in combating mirror flop issues common to the SCT. The autofocus routine moves "Out" by the specified number of steps then steps back in to build the focus curve, for the SCT it needs to go the other way or the backlash compensation required to combat mirror flop has it constantly spinning back and forwards, and I am not convinced with the drag of the grease that the mirror reliably stopped moving before the next focus image was taken.

Reversing the focuser direction should fix that, I checked and it actually does reverse the direction of travel that requesting an "In" move gets you, so now for autofocus it will move what it sees as "Out" and it will actually match the optical effect (The focal plane moving forward WRT the sensor) where it had the opposite effect before. It will also avoid constant shuffling back and forward to deal with the flop. It will make an anti flop "Backlash" move on the initial move away from focus then step progressively in one direction for the focus run before finally making a backlash corrected final move.

The theory sounds fine, now I need a clear sky to see how it works in practice.

I think I will stay with the thought above, I will go with SGP at least until the end of the trial period before I try any other software. Get the best of the trials so compare packages.
Reply With Quote
  #18  
Old 17-04-2019, 06:10 AM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 3,342
I have been playing with SGP over the last few nights, and plonking the gear in front of the garage any night that looks clear'ish to get some hands on. I am thinking I can get over the learning curve, but it would be nice to have a few of the things that APT does really well in there. To be honest, APT does plate solving and centering targets better, if for no other reason that when you want to refine pointing in SGP you get no feedback about where you have clicked on the solved image.

BUT, and it is a big one, auto focus seems to be reliable and that is a huge selling point for the SCT. You can run it over and over again and it lands consitently within a handful of steps each time, it just takes a bit of tweaking to get it working right due to the SCT peculiarities.
Reply With Quote
  #19  
Old 18-04-2019, 09:34 AM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 3,342
I ended up just sucking it up and buying a full license to SGP.

Having found software that appears able to reliably focus the SCT I am not inclined to keep hunting. Running the focus routine repeatedly has it land within a worst case range of about ten steps of the same position over and over again. At 1000 steps per focus knob revolution you could not do that reliably by hand without a 10:1 focuser and even then a lot of subjective choice needs to be made on what is right, unless you use a mask every time you focus.

A few nights of experience has put me a lot further up the learning curve in using it.
Reply With Quote
  #20  
Old 18-04-2019, 03:23 PM
ChrisV's Avatar
ChrisV (Chris)
Registered User

ChrisV is offline
 
Join Date: Aug 2015
Location: Sydney
Posts: 1,737
Welcome to the learning curve Paul!!
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 08:53 PM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Advertisement
Bintel
Advertisement
Testar
Advertisement