SharpCap Forums

Hi Robin,

I thought I'd seen posts of SC users enabling T.Compensation in SharpCap using the ZWO EAF. But the Focuser section of Camera parameters does not show the T.Comp checkbox, although it does show the temperature correctly. Searching shows mixed results.
Bringing up Focuser "Setup", does not show any controls for T.Compensation , e.g. a T.Comp factor.
I have just installed the latest ZWO ASCOM drivers (6.5.28) and updated ASCOM Platform to 6.6 (SP2), and updated SC to 4.1.12946.
Any suggestions on what I might be missing?

Thank you.
Cheers, Chris.

Hi Chris,

temperature compensation is something that is optional in focuser ASCOM drivers. Fortunately there is a way to ask if the driver supports it, so SharpCap does that and if the driver claims to support it then the checkbox appears. Since you aren't seeing that checkbox (or anything in the ASCOM setup), I'd have to assume that the driver doesn't support temperature compensation.

Based on that, and assuming that the ASCOM driver upgrade doesn't change anything, then it would seem to me that there isn't any support in the ASCOM driver - at least not obviously.

There may be software out there that does it's own support for temperature compensation (which is possible as long as there is a temperature readout), but SharpCap doesn't have anything like that and relies on temperature compensation being in the ASCOM driver.

cheers,

Robin

Hi Robin,

Yes, NINA supports Temperature compensation using the EAF, I believe. I guess it's done in the NINA software.

And it does seem logical for NINA, or other acquisition software, to manage any automated focuser adjustments, so they can be done outside of acquiring an image.

The ZWO EAF supports the readout of Temperature, as you know, as it's in the focuser panel. It would be nice if SharpCap had the option of making these focuser adjustments (a bit like you offering a few ways for backlash treatment). It's not complicated. And you'd have complete control over when it is done, which I think is important, especially if a T change induced focuser move also required a backlash correction.

Can I suggest this as a feature request?
Cheers, Chris.

Hi Chris,

the actual adjustments aren't too hard to do - either micro movements at any time (a few steps) or as you suggest to update between frames in still mode. The tricky part is that you need to *measure* the compensation rate first - probably by refocusing a few times during a session and recording the temperature/position each time, then plotting a graph and hoping it's basically linear. I guess I could leave it up to the user to make that measurement manually (adding something to help automate it seems like a lot of effort for a fairly niche use case). Hmm, interesting idea - will consider.

cheers,

Robin

Hi Robin,

Yes, I agree. Leave the measurement to the users. Just have a field in Hardware Focuser setup for the correction factor (steps per degree C) and perhaps an enable checkbox (or a selector between ASCOM and SC control …).

Cheers, Chris.

Hi Chris,

out of interest, how are you capturing images? I ended up thinking about this a bit more and the lowest impact way of getting something done quickly is to have this as something supported by the sequencer when capturing still frames - that's all set up to do things between still frames when necessary, which the rest of SharpCap isn't really at the moment.

cheers,

Robin

Hi Robin,

For me, it would be ideal if any (T induced) focus adjustment happened during a break in guiding (and image acquisition/frame acceptance) due to dithering. This gives many opportunities every few minutes.

That would then work in both Still and Live stacking modes.

Cheers, Chris.

Sorry, I didn't really answer your question.

I'm using Live Stack exclusively. I think I mentioned issues using Stills mode, at least with my laptop and camera.

So the best place to adjust focus is during dithering.

Cheers, Chris.

Hi Chris,

thanks - it's useful to know because Live stacking already has ways to do stuff (like dithering) between frames, so the same could be done for the focus update. It's easier to build something like this on features that already exist and are closely related than to do something from scratch

cheers,

Robin

Cool. That sounds promising.

Thanks Robin.
Cheers, Chris.

P.S. Seems that ZWO is keeping temperature compensation for its ASIair only. Guess that’s why Nina does it now. Will be great for SC to provide it.