M16 Eagle - 9.5 hours at F10

[g__day]

I'm trying my hand now at ISO 400 imaging (I usually use ISO 800). To preserve image fidelity I've done a few things differently:

1. Each day I shot at the same duration and create match dark to maintain temperatures
2. I try and frame the shot very carefully from the day I shot's starting position
3. I try and avoid longer duration shots when the moon is about

So the following is the fruit of my labour. With flats, flat darks and bias shots remove - this image is 30 shots totally 9 hours 25 minute of data on a C9.25 into a Canon 400D. The stacking is done in DSS and CS4 was used for levels and curves (and a very slight Gaussian blur on the dim region). I have combined 4 shots at 600 secs, 11 shots at 900 secs,
9 shots at 1200 secs and 6 shots at 1800 seconds).

I think my quality of shots is slowly creeping up! :)

Matt

PS

Thanks to Humayun for the image capture and processing suggestions! I've got a long way to go - but step by step I'm moving forward.

[jjjnettie]

Another WOW image. Such detail on the actual Pillars. Lovely!

[gbeal]

Slowly? Nope, racing away Matt.
Very nice, very nice indeed, and at f10 as well.
Gary

[David Fitz-Henr]

Great shot Matt, nice colour and good detail in the pillars !

One question - I have started imaging with a Canon 400D as well, and was wondering if there is any difference in what ISO setting that you use ? That can all be done later in the image processing, right ? Or do you get a better dynamic range by choosing the optimal ISO for the image in the first place ?

[h0ughy]

well done nice shot. persistance does reap the rewards

[g__day]

David,

I read a few Canon reviews for the 400D model and for astro folk were suggesting ISO 800 as the sweet spot. I did that for a year - improving focus, pointing and guided tracking particularly. Once I could do longer duration subs reliabily I asked folk with alot more skill than I and Humayun in particular suggested I go with ISO 400 shots.

One key thing I've just noticed in my darks is that at ISO 400 there is significantly less noise at 10, 20 and 30 minutes shots. In my equivalent darks at ISO 800 there was real noise past 15 minutes. Now noise can't be perfectly subtracted - so I think I'll stay with the lower gain of ISO 400 on my longer shots.

Hope this suggestion helps. It boils down to if your darks are truely dark at the duration shot you wish, and you're still getting plenty of signal - then you should be laughing with ISO 400. Try it and see.

Matt

[David Fitz-Henr]

Thanks Matt,
I have been doing all my work at ISO 200 (just posted another three shots from Friday night), and was going to try ISO400 last night but smoke clouds from bushfire preventative backburning ruined what would have been a nice night - that and a massive dose of hayfever ! I may try it tonight if the smoke blows away (looking not too bad this morning).

[dpastern]

Good details on the pillars, colours look a bit too magenta to my eyes, but other than that, well done.

Dave

[TrevorW]

OK fundamentally it's a nice image but I don't believe anything was gained by capturing 9.5 hrs of data at varying exposures especially for this wide angle view.

Others will probably disagree but it's just my opinion

[g__day]

Trevor,

Actually I think your dead right with that view - I was just experimenting. I think if you are not dealing with a high dynamic range target (e.g M42 Orion) then fixed duration shots should simplify your processing.

So I am shooting the Helix at 30 minute subs. Must say the burn offs are annoyance - given how faint the target is. Why they couldn't do this during the full moon or whilst there was alot of cloud cover puzzles me. First dark nights, otherwise clear skies they have to schedule their flame on skills!

Just bad luck huh?

[Hagar]

Very nice Matt, exposure time is the biggest improvement most of us can make and with 9.5 hrs you have the final result to prove it.

Well done.

[Octane]

Matt,

Getting there, dude.

I'd still recommend just sticking to the one exposure time. Your tracking is phenomenal, but, beware, you have to compromise the exposure duration with the hideous amounts of noise the camera is going to generate after copious length exposures.

Colour balance is something that can be worked on easily after the fact. But, you must fix your framing! :P

Regards,
Humayun