Temperature Compensation Redux


For the last couple of years or so, I have been pestering you guys to make SGP compatible with ASCOM temperature compensation. I’d like to renew that request or at least find out why you’re reluctant to do it. To recap the problem:

With TC enabled in an ASCOM compliant controller, the controller will ignore all attempts to move the focuser in order to prevent simultaneous move commands. That’s fine and as it should be. SGP correctly disables TC, if enabled, when it runs autofocus and then re-enables it when complete. However, with TC enabled, the move buttons in SGP are useless because the controller correctly ignores them. The only way to use them (which I often do when first getting started in order to get focus close enough for AF to work) is to disconnect the focuser, disable TC and then reconnect. Once focus is dialed in, I have to disconnect the focuser again, enable TC again, and then reconnect.

That’s not how an ASCOM driver is supposed to work. The user should not have to interact with the ASCOM interface once it is started. To be in keeping with the ASCOM standard, SGP should offer a way to disable and enable TC in the controller from the GUI, which it does not. An alternative and I believe acceptable approach would be to have the “IN” and “OUT” move buttons (and probably GOTO) disable TC if it is enabled, command the move, and toggle TC back to enabled when the move is done - just like AF does. This would allow people like me who use TC regularly to keep it enabled and still be able to move focus from the GUI.

I don’t want to come across as ungrateful or a pest. I love SGP and have been a faithful devotee for years now. But I also think that if SGP is going to claim compliance with ASCOM focusers, it should actually be compliant. If there is a good reason for not doing this (I have never been given a reason after previous requests) I’d love to hear it and will willingly accept it.

Thanks for your consideration.



We’re not against it. I think when you initially mentioned it we made the changes for auto focus to handle it better. I wasn’t aware that this was inadequate.

I guess your focuser doesn’t have a dialog to enable/disable it? Is this done through settings?

I don’t see a lot of value in adding another option to SGP to toggle things on and off. I’ll see about wrapping something around the move to handle this better.




Thanks for the quick response. I’m not aware of what changes you made initially, but autofocus works just as it should when TC is enabled. That’s not the problem. The issue is the move buttons when TC is enabled. They can’t be used. In my controller of choice (I have 3) the TC is enabled in the ASCOM settings dialog only.

My favored solution is to wrap something around the move buttons that toggles TC just like AF does. It seems like a very elegant solution.

Thanks for considering this.



I’m interested in this as well, as I will soon be moving to TC focusing. I also think the most elegant solution is if SGP silently turns off TC for a manual focuser move and then turns TC back on in the background.