some newbie help needed

[Stephen Greenfield]

Hi , I have been taking some wide field iimages of the sky and now that i have a hoya filter the results are somewhat better. I was thinking of trying to do some stacking . My question is the following, how many should i take what sort of exposure length etc ? I was thinking of just stuff like the plough etc.

I have the following equipment

Sony NEX 3 18-55 lens

Canon 1000d

Tripod

with the sony seem to get better results with the ISO in the 400-800 range before noise becomes a big issue, less noise with the canon, seem to manage 25-30 sec exposures without any star trails

Am i better trying to stack a few longer exposures or more shorter ones ?

[LukeSkywatcher]

Generally its better to stack many shorter exposures rather then a few longer ones. How long each exposure should be is entirely up to the light pollution situation in your locale. Itas a good idea to experiment with exposure times and ISO settings until you get a result that you are happy with. Then just take many of the same exposures and stack.

[Beyond_Vision]

If you are on a static tripod around 20-25s would be the max for a 10-20mm lens. Less time for longer focal length setting. You will also get rotation between frames which if you are using a wideangle lens which may cause problems with stacking.

I would experiment with your set up using the canon camera and check to see the maximum time you can expose for before the stars trail too much. Use ISO800 and take as many images as you can (a minimum of 16 frames would be a good starting point)

Regards

Kevin