Exposure time

Cosmic (Daniel) · #1 19-09-2011, 10:25 AM

Very basic but complicated question. I do my imaging with a EQ6pro 8" newton and 550d canon. Now im keen to make a big dark library, but what would be a rough time and iso chart I could go off?

I have been doing 5min subs @ 400iso and 800iso with a cam temp of av 32 degrees, could I go 10mins ...20mins to get more data? I guess that would that require me to drop the iso at that stage. I do get good results with 5min subs, with alot of targets on the other hand.

Tough one my next target is the Helix Nebula.After a failed attempt with 5min 800iso subs there wasn't much data to play with you could barely see it. This is where I need to push this setup, if that possible.

Cheers,

Dan

rcheshire (Rowland) · #2 19-09-2011, 10:14 PM

Hi Dan. If I understand your question. You are asking whether you should increase the exposure time of your subs to get more detail and you want a dark library to match.

Total exposure time is more important than longer exposure times. Optimise your exposure time for your sky condition and take as many subs as necessary. Then take darks of the same duration as your subs and preferably at the same temperature.

Cosmic (Daniel) · #3 20-09-2011, 01:56 PM

Quote:

Originally Posted by rcheshire

Hi Dan. If I understand your question. You are asking whether you should increase the exposure time of your subs to get more detail and you want a dark library to match.

Total exposure time is more important than longer exposure times. Optimise your exposure time for your sky condition and take as many subs as necessary. Then take darks of the same duration as your subs and preferably at the same temperature.

Hi Rowland and thanks for the comment. Sorry for asking in a roundabout way, but you have answered it. I can assume that a 10-20 min sub in very dark skys wouldn't be out of the question, but I don't have the pleasure of that lol. I'll use total exposure/sky condition as a rule of thumb from here on in. My Helix subs where quite white last imaging session, so shorter is the answer....look thanks for the help. At this stage bugger the dark library from the looks its best to take them straight after lights, because who knows what the conditions will be

.

Much appreciated.(a bloke gets autoguider package and just wants to do big exposures

)

Dan

leon · #4 20-09-2011, 03:52 PM

Daniel, excitement can lead to disaster when it comes to imaging, just keep it simple, and take it easy.

Start off with a few lights, say six, then take your darks during or after your lights, at about the same temp.

ISO nothing over 400, on occasions when it is needed maybe 500-600, and don't overdo your exposures at first until your get experienced with shorter exposures, and from there move on as the experience grows.

Leon