Help with Flats & Darks (294MC)

[bertinspace (Arnold)]

Just setting up my new (used) 294MC camera...

I noticed my flats (that auto exposed at 300ms) at gain 121 have a large round white glow in the centre of the stretched preview. This same glow appears in shots of deep sky as well.

The 120second darks also have a strage artifact in the centre of the image.....

is the sensor damaged?

[AstroViking (Steve)]

Hi Arnold,

You'll need to use longer exposures for your flats. The '294 and '183 series of cameras from ZWO/ASI are well known for not giving good images if the exposure time is under 3 seconds.

For my '183MC-Pro, I use 5 second exposures for the flats and dark-flats.

I can't help with the UFO-like glow in the centre of the frame - that's odd and nothing I've seen before.

Cheers,
V.

[Nikolas (Nik)]

That is a frosted sensor it is either the desiccant that needs to be changed/recharged or you need to cool slower in stages.

[bertinspace (Arnold)]

After some experimenting.....the vignetting is normal and just exagerated by the auto stretch in ASIair. After stacking and adding to final stack the flats worked perfectly

Results attached https://www.dropbox.com/scl/fi/rirmg...=kjhlh73m&dl=0

[ChrisV (Chris)]

Look at the flats linear not stretched - the later exaggerates things. And it should already be visible unlike lights