M27

[Erquy]

Hi

a first real trial with my newly received C8 on VX.

http://stargazerslounge.com/gallery/image/18607-m27/

40 minutes at ISO1600, subs of 45 sec/10 darks/flats, unguidded at f6.3 with unmodded canon EOS1100D.

Unfortunately, it is not getting that dark anymore up here in sweden and difficult to avoid some skyglow. Spent quite sometimes in processing and I would admit it is overprocessed but not that easy to take away the skyglow (natural, not much artifical light pollution). I could clearly see the difference if I process only the last 20 minutes when it was becoming really dark (but after midnight), more contrast in that case (but less details of course with only 20 minutes)

Shall I go down to 800 ISO, although of course I will need longer total time to get same details (but hopefully less skyglow?), ? OR shall I keep ISO1600 and go to f10 (still manageable at 45 sec)comment welcome on this

[michael.h.f.wilkinson]

Very nice result. Have you considered using narrow-band filters to cut back sky glow?

[Erquy]

Hi,

I have no filters of any kind today, and simply trying to get most of what I can without (and without modded camera). I am still learning and before adding more and more equipment, I prefer to get a full grip on what I have/can do (the more tools you have, the more possible complexicity, so my approach is go slowly and fully understand what I can do/not do with as little as possible.

Indeed I have been reading quite a lot about filters of various kind and start to understand and may move into this. As far as I see it, it sounds to me that you may need those filters when you are falling in several of following cases: 1) depending the type objects in order to get most of it -such as nebula filters which would be welcome here- 2) in case of very long guided exposure of several minutes -also required simply by the presence of the filter- 3) some light pollution. 4) modded DSLR or CCD

I would say I am not in any of those cases really (apart I was after M27 here, but I am not only after nebulas), no guiding, no light pollution (apart the natural glow of those short nights today), no modded camera, no long exposure

Personnaly, I am not after guided today and happy with the VX with up to 90 sec as I managed so far (in above case, it was only 45 sec sub and I rejected only 2 out of 60 subs when stacking -I did some trials at 90 sec but then I may need to reject 1 out of 3 or 4 sub and with the current night brightness, things are really getting bad on sky glow in the stack with 90 sec ISO1600)

I guess I don´t have much other choice those days that wiating 1 am to 2 am to shot... but I sill wonder simply on best ISO in such a case or going to f10.

Thinking it is only 40 minutes in total with a low of natural sky brigthness, it is still not that bad... simply maybe need to wait August to shot again with really darker sky.

What filter would you think of for adressing natural sky glow without having to extend too much exposure time for same level of result?