Flat issue, is it time for an upgrade?

[Ivor]

No such thing as a stupid question, as it is always easy to overlook a silly mistake
 

Frame	Temp	Offset	Gain	Comment
Lights	-10	?	0	No offset offered in NINA, assuming 0. FITS header didn't state anything
Darks	-10	50	0	FITS HEADER, same duration 300s
Bias	Ambient	?	0	Superbias of 100 subs taken a while ago
Flats	Ambient	?	0	No offset offered in NINA, assuming 0

 

Investigated the flats issue I've tried sky flats, light box & sketching panel with various card thicknesses of card to adjust the exposure time, I always get the same result.

I will recreate the Darks with unknown offset to see if that makes a difference.

  

 

Edited 7 hours ago by Ivor

[symmetal]

You've posted using gain zero. 🤔 Gain 100, offset 50 is the default setting and is most commonly used due to it's lower read noise, (and no loss of dynamic range), and is fine for all scopes and filters apart from possibly fast scopes taking luminance frames where the optimum exposure ends up being like 10 seconds so you end up with 100s of frames and spend as much time taking images as downloading them. I do this on my RASA 11 and ASI6200MM camera for luminance, but gain 100 for everything else. You wouldn't use offset 0 as that would mean black clipping your images which is the reason offset is used. If you're using the Ascom camera driver, check the Ascom driver settings for what the gain and offset is, if NINA isn't telling you.

If you're using darks there is no need to take bias frames as the bias is already included in the darks.

The lights and darks need to be taken at the same gain, offset and temperature.

You should take separate dark frames (flat darks) at the same exposure duration as your flat frames though you can use the master bias instead of the flat darks.

Again the flats, flat darks (or bias) need to be at the same gain, offset and temperature as long as the flats histogram looks good. This gain, offset and temperature need not be the same as used for your lights and darks, but it's more convenient if they are.

Alan

Edited 6 hours ago by symmetal

[Budgie1]

In NINA, the camera Gain & Offset settings are on the Equipment > Camera tab > bottom left of the screen under "Settings".

With my own ASI2600MC Pro I use Darks, Flats & Flat-Dark calibration frames and they're all at the same set point temperature, gain & offset settings.

[vlaiv]

18 minutes ago, Budgie1 said:

With my own ASI2600MC Pro I use Darks, Flats & Flat-Dark calibration frames and they're all at the same set point temperature, gain & offset settings.

That is probably the safest approach.

@Ivor

Try using it. Next imaging session - do darks, flats and flat-darks, all with the same settings, just to make sure and rule everything out.