M31 sensor noise

[wormix]

Hi all, i took 40 x 3 min subs of M31 last night - just started doing some quick stretches this morning - exaggerated image below;

Is all the noise on the right from a hot sensor?  Camera is a new to me unmodified 600d

ta

 

[michael.h.f.wilkinson]

Could be. If so darks should reduce the issue

[wormix]

Ah, should have mentioned - also did 20x darks

[alacant]

4 hours ago, wormix said:

the noise on the right from a hot sensor

Hi

I don't think so. We regularly image with our 700d sensor well over 30º.

Best not to use dark frames with a 600d, but unless your processing skills are at the rocket scientist level, essentiall to take flat and bias frames. Dither between frames would also help enormously. The last thing to do before you stack is to remove any bad frames (cloud, trailed stars ets.) then, before you process, be sure to trim the edges of the stack to remove edge artefacts; there always are some.

Cheers and clear skies

Edited September 14, 2020 by alacant

[wxsatuser]

3 hours ago, wormix said:

Ah, should have mentioned - also did 20x darks

What about some decent flats.

[wormix]

5 hours ago, wxsatuser said:

What about some decent flats.

did some really quick and dirty flats and bias this evening to see if it had any effect and its made a world of distance - all that area of exposure has gone.

onto another issue now, where i cant seem to get a nice clear histogram after messing with DeepSkyStacker settings earlier!

[wormix]

Update - pressed a button in GIMP to display Logarithmic histogram, so wasn't DSS at all.

Talk about learning curve!

Out again tonight, going to try at ISO800 this time, and potentially drop the exposure down to 120seconds.  Will also get some decent light frames.

Cheers
 

[StuartJPP]

Was the rear LCD on at the time? I.e. was the LCD displaying the shutter timer during the exposure?

I've seen a similar pattern on captured frames when the LCD of my 650D was on during some testing.

[wormix]

15 minutes ago, StuartJPP said:

Was the rear LCD on at the time? I.e. was the LCD displaying the shutter timer during the exposure?

I've seen a similar pattern on captured frames when the LCD of my 650D was on during some testing.

Unsure as it was swivelled round (does that automatically turn it off?) and I was using remote via APT. 
 

I did wonder if it was some stray light entering via the viewfinder?

[StuartJPP]

12 hours ago, wormix said:

Unsure as it was swivelled round (does that automatically turn it off?) and I was using remote via APT. 
 

I did wonder if it was some stray light entering via the viewfinder?

I doubt that it would be the LCD then.

It can definitely be the viewfinder causing it, best cover it up for next time to see if it helps.

If your darks aren't showing similar issues it will almost certainly be that.

 

[wormix]

16 minutes ago, StuartJPP said:

I doubt that it would be the LCD then.

It can definitely be the viewfinder causing it, best cover it up for next time to see if it helps.

If your darks aren't showing similar issues it will almost certainly be that.

Had another session last night - still to look at the data but did an auto-stretch in APT of my flats and they show a similar pattern even with lcd definitely off and viewfinder covered. 
 

At least now with some decent flats & bias I can cancel it out.