why am I not seeing the same detail a year later?

[blinky]

I have went back to SH2-232 to get some more data at the bottom is the original post early last year. Anyway, same scope, same camera, same gain, same Ha filter and no moon.  The left image is a few minutes ago and the right image a year ago with the same stretch applied in Pixinsight.  Im trying not to get paranoid and think I have a problem with my ASI1600MM but why is this years data so much fainter than this time last year?

 

 

 

[blinky]

Even if I up the gain to 300 I still dont see the same detail as I did at gain 200 last year, Im confused.....  Looks like cloud but it seems 100% clear to me and my guiding would suggest the same.  Dawned on me one difference - last year was shot with the native ASI driver (Hence why I can see offset is 60) whereas this is with the ASCOM driver

Edited January 12, 2021 by blinky

[vlaiv]

Different transparency?

[blinky]

Dunno, maybe but never thought it would make that much difference

[vlaiv]

Just now, blinky said:

Dunno, maybe but never thought it would make that much difference

Oh, it can make quite a bit of difference on faint objects.

It can make half a mag difference in brightness or even more. It can reduce signal to 63% of the other one.

Do a light saber check? Do you have torch with you? Shine it up in the sky to see if you get "lightsaber" effect. This will show you if there is local fog.

I checked Copernicus - most of UK has excellent transparency at the moment.

[blinky]

I can see a beam yes, but it is now starting to cloud over with some high cloud, so I suppose that must be what it is and not a faulty cam!