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GPFocussed
15th of July 2009 (Wed), 23:40
Hello ,
I will have an opportunity in the next few weeks to be up north where there are a lot of clear skies to give some astrophotography a try. I want to try to shoot the Milky Way. I already have DeepSkyStacker but I am not entirely clear on the procedure of taking pictures.
I am planning on taking about 15-20 Light Frames of the Milky Way itself around ISO 800 on my Rebel XT with my 18-55 kit lens stopped down to about f/22. I am assuming that 30 second exposures should be adequate to avoid star trails. I just have a few questions regarding the pictures I have to shoot, namely:
· How does one determine how many darks/ flats/ biases to shoot for approximately 20 shots of the actual Milky Way? Is there a table that one follows to determine this?
· If I understand correctly, does DeepSkyStacker save darks/ flats and biases as master files that can be used again and again on a variety of projects? This is assuming that the camera is always set at a consistent aperture, ISO speed and shutter speed for all the pictures you take or do you have to take new ones on each separate shoot you conduct?
If anyone has any links to contribute that relate to the use of DeepSkyStacker and the process of taking images, etc. may you please post up a link??
Thanks in advance P.O.T.N. Members!
hollis_f
16th of July 2009 (Thu), 04:33
Can't answer the DSS questions as I've only used it once, and that was stacking light frames only.

But I'm not sure why you plan on using f/22. Not only will it severely cut down the amount of light getting in, but it'll possibly cause blurring due to diffraction. When I tried this in Southern Africa I used 30s @ f/4.8 and that was only just enough.
chris.bailey
16th of July 2009 (Thu), 04:42
There is a yahoo DSS forum which has loads of info. Equally I have used it since day one so am fairly comfortable with it if you have any specific questions.

Remember that the overall aim is to reduce noise and that noise reduces as a square of the number of frames. As such I regularly take 100 darks (lens cap on, similar temperature to the light frames) so that my darks dont ADD noise to my lights. Flats are more problemmatical. I tend to take sky flats and can rarely be bothered to take more than 10 or 12 (I often dont bother at all with Flats)

DSS does produce Masters that can be re-used but beware that Flats will change night to night and darks really need to be at a similar temp to the lights.

I often dont bother with any of them but I do have a CCD which has very low dark currents. For wide angle shots I would be tempted to not bother.

Limit shots to 15-20 seconds, ISO 800 and shoot wide open.
GPFocussed
17th of July 2009 (Fri), 00:54
Thank you both for your responses. I guess I will be reconsidering the f-stop that I was going to go with. My assumption was to get more detail with that type of aperture.

Chris, would you happen to have a link handy for this Yahoo Group you were talking about?

Thanks again Guys!
chris.bailey
20th of July 2009 (Mon), 07:33
Thank you both for your responses. I guess I will be reconsidering the f-stop that I was going to go with. My assumption was to get more detail with that type of aperture.

Chris, would you happen to have a link handy for this Yahoo Group you were talking about?

Thanks again Guys!

http://tech.groups.yahoo.com/group/DeepSkyStacker/
DSLR AstroMod
20th of July 2009 (Mon), 09:26
If you need any more info PM me, astrophography is my biggest passion by far!
GPFocussed
26th of July 2009 (Sun), 00:10
Thanks again for your responses guys. DSLR AstroMod, I will keep that in mind if any further questions do arise.