Short Exposure Time Blank Image

[Victor S]

Using ZWO ASI294 MC pro, when I set exposure time to any value less than 1 second in the sequence tab, to create bias shots for example, the image returned is blank.

[Dale Ghent]

Hey Victor, could you please attach an example FITS or XISF file to this ticket so I can take a look at it?

[Victor S]

This is a one second bias capture.

[Victor S]

And here is a 0.5 second bias file taken with everything else set up the same as the 1 second file.

[Dale Ghent]

Here are the two images (0.5s on left, 1.0s on right) with STF applied to both. What’s strange is that there seems to be some sort of data in the 0.5s one - a single lone hot pixel in the lower-right that is evident in both images at x=1813 y=1277. But why the image appears to have no values for the other pixels is really strange. The lone hot pixel would seem to indicate that the camera is handing us data.

One other NINA developer has an ASI294MC as well, and I will ask him if he recognizes this issue. In the mean time, would you mind trying a similar short exposure, but connecting to the camera via the ASI ASCOM driver? I’m curious to see if the ASCOM driver behaves similarly.

[Yannick Dutertre]

Per ZWO, you should not be taking or using bias frames with their cameras, and especially with the ASI294MC Pro, which gives inconsistent results at exposures less than one second (this is also per ZWO). Flats with this camera are also recommended to be 2-3s long, and at least 1s.

[Yannick Dutertre]

That being said, as Dale suggests, it may be interesting to try the same experiment with the ASCOM drivers - and see what data is generated. Maybe there is a bug in our impl of the native drivers, and you could help us find it! So your help is very much appreciated.

[Victor S]

I did another test tonight using the native driver. Here are the results. It looks like whatever was happenning the other night is not repeating.

Either way, I'll stay away from shorter than 1 second exposures. Thanks for the advice on the bias shots Yannick.