M101 - the learning curve gets steeper

[Sparrow]

Thanks to a reasonably clear night last night I managed to get another 1 1/2 of data on M101 giving a total of 4 hours - a mix of ISO 800 at 8 minutes and ISO 1600 at 4.5 minutes and ISO400 at 10 minutes (the debate rages on as to which is the best ISO)

I seem to have solved some of my guiding problems but am still fighting a poor signal to noise ration on the red channel - the problem seems to be noise rather than a weak signal even though the Canon 1000D isn't modded - wish I could establish what the source of the noise was - possibly ampo glow, possibly sky glow from the mulititue of light pollution sources round here in Chester.

Anyway, I'm still experimenting with different routines, programs and methods for processing and this seems to be the best result so far. Hopefully more experimentation will yield a better result.

[Tim]

Thats coming along nicely. M101 is a fabulous galaxy to image, and it is surrounded by other fuzzies too, loads of them. Grabbing images when it is high in the sky will help pull out the fainter fuzzies and the fainter parts of the arms, as will the longer sub lengths.

Might be worth going through your individual subs and looking for any with obvious bad trailing issues. The stars show a bit of a teardrop shape at the moment. Also, it might just be my eyes (waiting for new glasses) but the focus looks ever so slightly soft. Focussing a dslr is tricky at best. Are you using a bahtinov mask? If so, be sure to get the centre spike line absolutely central. Also, on the C8, its worth checking the focus every hour or so, I cant tell you how many clear nights I have wasted on soft images for not doing that!

Nice pic anyways, looking forward to seeing this one progress

TJ

[Sparrow]

Thanks TJ

The cigar stars are from a lack of coma corrector. As for the soft focus - that is really frustrating me - the focus is fine and sharp but to lose the noise a gaussian blur is almost essenial so it loses definition and obviously blurs the image. I'm hoping to reduce the reliance on gaussian as I find better processing steps to take and find solutions to the weak red signal.

When I'm back at my other computer tomoorw I'll post the B/W image taken just from the blue and green - the quality is considerably better - only when I work on the red do the problems start.