When will this bug be fixed eventually?


SGP is advertised for outstanding features as to e. g. focusing (re-focusing [auto focus] without changing the frame, good focuser backlash compensation, focuser temperature compensation) and integration of plate solving. On the basis of these properties I decided to buy SGP without having had the chance (due to bad weather conditions) to test each of its features thoroughly during the 45 day trial period. When it came to test the focuser temperature compensation, Gary ( Temperature Compensation Implementation ) remarked the guess that there was a flaw in the temperature compensation and put a feature request to fix it ( Temperature Compensation Fix ). I analyzed his logfile, demonstrated that temperature compensation in SGP was indeed using a wrong algorithm and presented the correct one. Up to now, there was not a single reaction from the developers, and - surprisingly for me as well - neither from SGP users.

The bug is known since 26th of november 2017 and has to be fixed. I wish to see the fix in v2.6 and not only in v3.0, because temperature compensation is an advertised feature of SGP, but does not work correctly.

I am not nervous about the bug not being fixed yet. However, what really makes me angry is the fact that there is NO reaction from the developers to this qualified bug report at all. Did you even notice this? A short reply would be appreciated.



Bernd - this appears to be an oversight - as the temperature prompted AF routine works on absolute delta temperatures since the last AF routine. Temperature compensated focus seems like a great idea but in practice, I think the whole concept is flawed and you may find that temperature triggered AF gives a better result.
I have a number of scopes and I abandoned this idea, since I found it impossible to get repeatable results from one night to the next. For instance, the glass mirror on my RCT takes considerably longer to react to ambient changes than the outer structure, or in the case of my refractors, the aluminum tube over the inner optical elements. If the ambient falls quickly rather than slowly, I could actually make the focus shift change polarity.
Many issues are fixed very quickly, and it is not unreasonable for some things to take a little longer, in this case just 20 working days and counting…


Yes, Bernd, the lack of response has been disappointing, since it is an identified flaw which has a fairly easy fix. Temperature compensation for my refractors is important and works fairly well as is for quick temperature fluctuations, but would be even better if the developers at SGP could address the problem, which occurs when the temperature changes are less dramatic.



Hi Bernd - I have not reacted to your posts because I do not use temperature compensated focus and instead use the temperature prompted AF routine. The focus I obtain from my three refractors - on two rigs, one remote one at home - is excellent.

I can only imagine that Ken and Jared are working as a priority on the new 3 beta (and amending any bugs introduced along the way, eg latterly Dome slaving and roof close from park) rather than address your post when there is a functioning alternative focussing method.

Your view is of course that focussing can be improved and I’m sure Ken and Jared will consider your observations and data when time and priorities allow.

You may be aware that Ken and Jared are considering whether the change in subscription model may allow one of them to devote much more time to SGP. At the moment as I understand it, both work full-time and also have all of the other demands on time that many of us experience, eg families.



We will address this as soon as possible.


Jared Wellman
– Co-Founder and Developer


Thanks, Jared.


Hi Chris, Gary, Barry and Jared,

With my refractor (Takahashi FSQ 106N) the contribution of the refractive index of the glass is so much larger (and in the opposite direction) than the contribution of the aluminum tube that it amounts to a constant negative temperature coefficient. I have shown that for my refractor, see http://forum.mainsequencesoftware.com/uploads/db2508/original/2X/7/716c1d5c68cb93eba78b72fbe1054f59e0cc7c35.JPG
So I am quite confident, that temperature compensation in my case would work very well, if only the correct algorithm in SGP was utilized.

No, I am not upset because the fix is not yet accomplished - it is the complete absence of any reaction from the developers that bothered me. The arguments were simply ignored. That’s a pity, especially because the issue is obvious, the solution was given, and it would take a small effort to fix the problem. I don’t want to bitch, I (like others in this forum) am interested in the further development of SGP.

This forum is the only way to establish contact with the developers. I don’t know what to do but post again when I get no response.

Thank you for your response, that’s great and I appreciate it.




I still have two related requests:

  1. Please, when you fix the temperature compensation algorithm, consider to implement a threshold for the focus position when temperature compensation is enabled - as I proposed in the subsequent feature request: Focuser Temperature Compensation - Focus Position threshold

  2. … and a more accurate setting for the temperature compensation coefficient as proposed here: More accurate setting for the temperature coefficient

These modifications would enhance the usability of temperature compensation considerably.

Thank you again,


Temperature Compensation Fix

I’ve also graphed a negative TC for my TOA-150B. Using SGPs temp compensation has worked very well for me. I do limit the time and temp to 70min or 1.5 degrees though. After the trigger, the new auto focus is usually very close to the last TC focus position. I’ve been thrilled the focus can stay this close throughout the night. I suspect I could see some of the compounding issues if I had longer time/temp intervals though. I also suspect, from my data, that the Temp coefficient for my ota @ 25 deg is different than @ 50 deg.
Phil Montgomery


You continue advertising “Between-frame temperature compensation”, but it just doesn*t work correctly.

We will address this as soon as possible.

Any idea when this will happen?



Hi Jared,

You continue advertising “Between-frame temperature compensation”, but it just doesn’t work correctly.

We will address this as soon as possible.

Any idea when this will happen?

Is there a chance to get an answer?