Nothing but problems!


I think I just wasted my money on SGP. Have played with it now for a month while waiting on a decent night, thought I had it somewhat figured out. Finally get a clear night, spent two hours just trying to get auto-focus to work. Never been more confused. Finally just gave up on focus, try to run a sequence, It attempts to auto focus again for another 10 minutes, then never runs a sequence, never snaps a shot. Pretty much wasted another night. Fired up BYEOS and was imaging in 5 minutes. Of course that does nothing for my auto-focus, no plate solving.
Tired of reading the manual over and over to only get no where.



There is nothing more frustrating than struggling with software in the dark as time ticks by - we have all been there. Auto focus is one of the more challenging things to get working so I suggest you not try it until you get the basics working. Try a simple sequence without auto focus or plate solve. Once you get that working. Try adding plate solve. Only then try adding auto focus.

Astrophotography is very challenging in that you are trying to get multiple pieces of software and hardware to all work together. SGP is quite reliable but like any new software you need to learn how to use it. I suggest two things. First, during the day connect all your hardware and do as many steps as you can to gain familiarity. Second, when you do try things at night use only the basic operations you need at first and then add functions as you gain experience.


I concur with DesertSky’s comments. I have been using SGP since the first days so as it grew and added features it was easier to keep up with developments. There is a lot to learn, understand and I have struggled at times but just take one step at a time. I find using Photo shop and other processing software difficult but keep persevering and learning.
I assume your focusing system work OK with its stand alone software/system?
There is also first class support for this software from the developers and members so if you cannot solve your focusing problem then post a description on this group and I am sure you will get some help.
All the best,


Autofocus is challenging.I took me at lest three to four night to get it ti work, but once you have the setting worked out it is a dream to use.


We can’t help you if you don’t ask and don’t post your log files. If you’d like to send me a PM I’ll log into your computer via TeamViewer and make sure it is set up correctly.

SGP relies on quite a few programs and that can be frustrating. But, we can’t help if you don’t ask.



I would love for someone knowledgeable to take a look at it first hand. Like I said, I spent a month just reading and entering in settings as best I could, just trying to be clear on understanding documentation. I wasn’t too surprised that I ran into autofocuser issues, but when I just canceled that and could not even get an image sequence to run, I was very disappointed.

I’ve used these as guides.
SGP first week
Light Vortex SGP
SGP Pro manual

As far as equipment. I am using a pier mounted Celestron Edge HD 8 on a Losmandy G11 Gemini2 with F7 focal reducer. My imaging camera is a Canon T4i, my autoguider is an Orion mini guider deluxe with an ZWO ASI120 mm-s camera, controlled by PHD2. I recently purchased and installed a usbN stepper focuser from Rigel systems. It works fine manually.

I primarily use stellarium and the Losmandy software for telescope control.
I assumed my biggest current problem is the autofocuser routine. But I was unable to even get the image sequencer to run last night after cancelling the autofocus routine.

I have created multiple equipment profiles for the Edge HD 8 and my Explore Scientific 102 triplett. All I am concerned with now is the Edge HD 8 and just getting auto focus and image sequence going.

I don’t doubt that others are getting excellent results. That’s what brought me to SGP in the first place, the excellent reviews. But apparently I am or have become lost in the documentation at this point.



Hey Randy,

Is your stepper hooked directly to the focuser of your edge or is it attached to a Crayford? Does your scope exhibit backlash?

Set up TeamViewer and I’ll run through your settings. Send me an PM with your cell/email address and we’ll figure out a time to run through it.

SCTs are difficult because we need to measure the backlash so we can put that into SGP. Beyond that, we should be able to figure everything out.

Thanks, sorry you’re having trouble. It helps to have a mentor for these kinds of issues.



The stepper is hooked directly to the stock focuser knob. I do not seem to have backlash but honestly I have not been able to use it much since installing it. I will have to find the teamviewer program and load that. I have never used it. Will get you my personal info out today. I normally am at work 8am-5pm here on the east coast.
This would need to be don under night sky or before dark? Clear skies have been very few lately.

Thank you very much,

Randy Flynn


I used autofocus with the primary of Edge and it works well. Here are the main things to set up:

Make sure the focuser is turning counter clockwise as the focus numbers go from high to low. SGP only takes autofocus curves from high to low - and you want the direction to be CCW so it is pushing on the mirror.

Once you have that set, enter a backlash value that is at least about half a turn of the knob. This will depend on step size. SGP will let you set the backlash compensation so that it kicks in when you need to turn the focuser clockwise (to higher numbers).

Once the above two things are set you will find that changing focus clockwise will take much longer because it will overshoot and then come back ccw. But as long as you always take out backlash that way, the system should end up in a stable focus position and things will be repeatable.

Now you can use frame/focus and short exposures to find focus manually - by starting from high numbers and stepping down until the stars are small. At that point you can try an autofocus curve with about 9 steps. The step size should not be too bit or two small. Ideally it will trace out a curve that has a good shape and isn’t too steep or flat.

I use a C filter and exposures of 2 seconds for my system.

Doing autofocus will involve long periods where nothing is happening because backlash is unwinding. And at the end of the autofocus process it will sit there saying ‘complete’ when in fact it is still unwinding backlash and coming back to focus.

Oh - and set the minimum star size to a small number like 2 at first - to make sure you are measuring all stars near focus. Then increase it later if it is picking up noise instead of stars.



just to chip in - I use a celestron c11 with a feathertouch focuser from Starizona - backlash hasn’t been a problem for me and I have used SGP since the early days. It has been difficult to get good focuser curves though and I haven’t been able to work on improving it as the cloud cover at night has been very problematic here in the U.K. I can confirm though that autofocus works using sgp and the C11.

As has been advised, keep things simple to start, otherwise there are too many interacting variables and you can’t pin down the problem.

Good luck with it - help here is first class as long as you can provide the information required for fault finding.



I think that if you are having trouble getting good curves you should consider the focus direction and appropriate backlash compensation - as I described. Those things are important even without autofocus - when focusing an sct with the primary mirror. Adding something like a feathertouch to the focuser knob won’t change those issues.

The details I described may be a burden when getting things set up - but they are important for getting good and consistent results. Once you get it working it is automatic and shouldn’t require any more tweaking.



Frank can you post a picture of your autofocus settings? It’ll help me get a baseline.


Thanks Frank I appreciate your input. My real issue is that it was cloudy
virtually every night between October and March. …



Here are two views of my autofocus settings. For an SCT the step size will depend on how the focus motor is set up and how it is geared to drive the focuser knob - so it could be anything. In my case 500 steps is about 1 turn of the knob - so it is about 0.72 degrees per step. I have my autofocus step size set to 5 steps - or about 3.5 degrees - and I take 9 data points. My backlash is 500 steps or a full turn of the knob.

So in a focus run it turns the knob a full 360 degrees clockwise to remove backlash - and then it comes back pushing up on the mirror against gravity. Then it takes the full focus curve in 9x5 steps, which corresponds to only about 32 degrees turning of the focuser knob. The final focus accuracy is about +/- 2 steps or +/- 1.5 degrees roughly - and it is very repeatable.

Here are some pics of my settings:



Here’s a focus curve from last night:


The above was taken with EdgeHD11 viewing a field of stars in the milky way at 2s exposures with C filter.

The seeing was very good so the curve is well defined and goes down into the low 1" fwhm range.

If the seeing is not as good the curve will be much flatter and you might need to use a larger step size. So the ideal settings will depend on many factors. This is the shape of the curve I aim for - so that it shows the curvature near focus and lets you get a sense of the width of the “in-focus” range - which in this case is about +/- 3 steps.

Other people aim for a very sharp V - but that loses a sense of the region near best focus - and when it’s done you can’t tell how well it ‘hit’ the best value.



You might not have backlash, but you almost certainly have some amount of mirror flop as almost all SCTs do. You want to setup the backlash compensation such that it moves the mirror against gravity. You could start with a random amount maybe like 50-100 steps and see how that works.



Just wanted to thank Chris again for taking the time to remote into my machine and help me out. We didn’t have clear skies but hopefully he has me heading in the right direction. The next opportunity I have and weather permits, I will be determining my step size, backlash and proceed down the path to auto focusing. Definitely more to it than I thought there was.



Just remember that you aren’t flying blind because with an sct you can feel the backlash and loading of the mirror as you turn the knob. The backlash compensation is probably at least a half turn of the knob.

So an important thing to know is how many steps there are in a full turn of the primary focuser knob. That will be dependent on your setup - but it’s easy to determine by watching the knob and telling the focuser to step perhaps 100 steps initially - and seeing how far it goes.

Once you know the number of steps in a full rotation, a good starting point would be to set backlash compensation at half that number, set number of focusing steps to be 9, and set the steps between focus positions to be the number of steps needed to turn it 5 degrees.

This would cause the autofocus routine to go through 45 degrees turn of the knob - which is more than what I show above, but should be a good starting point. If it is too flat, make it bigger; if it is too steep make it smaller.

So - you don’t need clear skies to determine many of these numbers - and you do need to be physically at the scope and watching it to know the physical step size, in degrees, and to know which direction turns the knob clockwise vs. counter clockwise. It is important that as the focus numbers go down, the knob is turning CCW - so the mirror is being pushed up against gravity.



Just updating those that are interested in this thread. I have had cloud and and or rain since Chris gave me remote help. So I have yet to try the autof-ocus changes and run an image sequence. I don’t recall ever seeing a summer quiet like this before. So much for the sunny south. Will report back when I have some details