SharpCap doesn't fully cool my camera

[tc.astro]

I have a QHY600C and SharpCap can only get the temperature down to about -14 degrees. I can use Sequence Generator Pro (SGP) to get the temperature down to -20. It seems that SharpCap is only applying half the cooler power.

Is there a workaround? Can I turn off the SharpCap cooling? If I use SGP to cool the camera and then connect SharpCap the camera starts warming up to -14. Quite frustrating.

Seems to be a bug with SharpCap. Using auto SharpCap tries setting the cooling to 255. I tried setting the cooler power to 500 but SharpCap truncates it at 255. Setting the value manually to 100 sets the temperature to 2 degrees.

This might be an easy fix. Allowing the user to set values greater than 255 may do it. Or, better, scale the values so that 100 does the trick.

[tc.astro]

I should add that I'm using the latest SharpCap and QHY drivers which includes the QHY driver released yesterday.

[admin]

Hi,

I wonder if this is not to do with the cooling, but to do with heat generation - SharpCap runs the camera to capture frames all the time, while SGP only captures when you ask it to (like the difference between a video camera and still camera). If SharpCap is keeping the camera busy then the additional heat generated will offset some of the cooling. You may find that setting a longer exposure which will make the camera less busy (say 20s instead of 20ms) will have an effect.

255 is the maximum value for the cooling power for qhy cameras (at least according to the documentation).

cheers,

Rob8in

[chongo228]

Would turning off the live view mode in the top left work? It's new with 3.3 and I have not used it but I believe it toggles between treading your camera like a video camera or a still camera.

It's in the top left menu. Turn live capture off and see if the camera temp drops.

[tc.astro]

No, it's definitely a bug somewhere. I can set the camera to 60s exposure in both SharpCap and SGP and only SGP can cool the camera to -20.

Why is SharpCap allowing a value of 255 for the percentage? If 255% is OK then perhaps 512% is OK too. Maybe that will fix the problem.

[tc.astro]

Another problem - maybe related or maybe not - is that when I do a sensor analysis (at -12 degrees) it aborts with a message "minimum exposure reached." The exposure shown is 1.74ms but this camera can go way below that - it can go down to 0.001ms.

I suspect that SharpCap and the QHY driver aren't copacetic.

[admin]

Hi,

on the subject of the sensor analysis, I checked over the code and discovered that the minimum exposure error message can actually appear (incorrectly) for two other failure reasons:

* The camera has been disconnected during the analysis
* SharpCap couldn't adjust the exposure to get the desired image brightness of about 65%

I suspect in your case it may be the latter problem. To dig into the reason why that's happening, please post the full log captured after a failed sensor analysis run. Sometimes we discover with things like cameras actually having steps in the exposure lengths that they can implement (for instance specifying and exposure between 1.1 and 1.3 seconds on a certain model of camera gets you a 1.2s exposure).

I'm not sure what else to add about the cooling problem – I will ask QHY if they have any suggestions.

thanks,

Robin

[admin]

Sorry, one more question...

If you run SharpCap and select the camera 'QHYCCD-Cameras-Capture' you will end up controlling the camera via ASCOM in SharpCap, the same way that SGP runs the camera. What temperature can you achieve using that approach?

cheers,

Robin

[tc.astro]

It's too hot here now to do any more tests - the camera only goes 35 degrees below ambient (I have managed 38). But when I tested the ASCOM driver I saw two things:

The ASCOM cooler power ranged from 0 to 100
The temperature was much lower than using the direct driver - that may be due to the reduced frame rate

When I used the direct driver in SharpCap and 255 cooler power then simultaneously connected using SGP the ASCOM driver reported 50% cooler power. SGP then lowered the temperature further than SharpCap.

The 50% is the reason I suspect that the cooler power should be 512.

I ran a sensor analysis using the ASCOM driver and ran into the same problem - it aborted due to not being able to reduce the exposure. I see that other people have been having this problem with QHY cameras.

[admin]

Hi,

let me try a little tweak on the power level maximum for you in the next 3.3 update to see if that helps.

cheers,

Robin