Old 03-04-2006, 09:44 AM
Mick at Coffs Harbour

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Join Date: Aug 2005
Location: Nana Glen
Posts: 43
Best choice of camera??

Hi all.
Have decided to try a camera on my gso dob but not sure what to expect.
I see great pics which came from webcams connected to laptops but was thinking of a slr to use for general snaps as well. Do webcams go in real time as in look at screen instead of eyepiece? and if so are they equal to what eyepiece? (4mm...25mm, variable etc). is there a SLR that will act as both?
Sorry if these questions are silly but I know nothing and am only getting bits and peices combing the forums. Many thanks for any help or links.
Cheers and thankyou from Mick.
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Old 03-04-2006, 10:56 AM
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[1ponders] (Paul)
Retired, damn no pension

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Join Date: Nov 2004
Location: Obi Obi, Qld
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Hi Mick.

If yo have a look at the Icemans images of the planets (Images) you will see what can be achieved using a Dob and a webcam. You do however need either one of two things to be really successful, an eq platform for you dob, or extreme patience. Mike (Iceman) also written a review on imaging through and with a dob here . Have a good look through both before coming to any sort of decision.

Webcams do show in real time on your laptop screen but rarely if ever as good as what you see through the eyepiece yourself. No DSLR that I know of that will show real time. You need to capture first and then download and then usuall process to bring out details.

If you are thinking of using an slr without equatorial tracking then your exposure limit before star trails start to appear is T (sec) = 700/FL (approx) so the longer your focal length the less time you have. With a 50mm camera lense you will have about 14 sec before trailing will appear in your image. With a 1400mm FL scope you have about 0.5 sec before your stars start to elongate into trails. If photography is only a passing interest then try a few afocal shots first with a digital camera shot through the eyepiece and see how it feels for you before diving into the money pit.

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Old 03-04-2006, 11:31 AM
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lots of eyes on you!

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Join Date: Jun 2005
Location: Launceston Tasmania
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They way I have gone is firstly the webcam option cos it is cheaper (<$200 for camera and adapter). It means i can do planets. To get to this size of image, I had to have tracking. this cost me $600 for some motors to drive my newtonian on a dob base.

I have included a single image of when everything went pretty much to plan. This what you can see thru the laptop screen. This is pretty rare though. Generally, you have to stack 300 to 400 of these to make a final image.

The toucam and newer models are roughly equivalent to a 6mm eyepiece. So therefore this image is a 1250mm (my scope's focal length) divide 6mm (aprox for the toucam) = 208 x 7.7 (for my 5x powermate but with a 100mm extension) = 1600x.

You might get these types of conditions 5 times a year. Also it is a snapshot. The eye is quite forgiving and will pick up detail, if the object is moving around.

Planets aside, I will be spending the $1200 on a canon 350d for longer exposure deep space objects in the next few years.

The big question is not the quality of the camera, as what the guys on this site have produced with the canon 350d is outstanding. The question will be how good my tracking will be. For a planet, i am taking 1/10 shots. For longer exposure, I want to 30 seconds!!!

My gut feel is that I will need to spend another $1500 on a decent tracking mount.

As 1ponders mentioned, welcome to the money pit!
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Old 03-04-2006, 04:51 PM
Mick at Coffs Harbour

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Join Date: Aug 2005
Location: Nana Glen
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Many thanks guys for the info, yes it was mikes pics ( and others on the site) that got me going but one thing I completely forgot about was tracking...also I read that there are a lot of praise for film camera's as well, I have a good old Pentax slr 35mm so maybe a tracking mount first might be the way to go. Planets are what I am most interested in so a colour webcam may be my choice for a backup I think.
Thanks again guys, I won't rush into anything just yet. Cheers from Mick.
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