Buying a scope, dobsonians and webcams?

Hi folks,

I'm helping someone worth through their options for buying a scope. They have in the order of hundreds to spend. We've stopped discussing astrophotography as suitable scopes are out of budget, however they are interested in webcam work.

What I'm not sure about is whether a dobsonian is practically any use for planetary imaging. Its possible, but has anyone here tried it? I've concerns that keeping the object in view might become tedious very quickly, and put them off.

To get a scope on an equatorial mount, withough motors would mean getting something like a 6" newtonian on an EQ. But for the same money you can get a 10" dob. I'd rather advise to get the dob, but not if doing webcam work would tedious to the point of putting them off.

Any thoughts?

Cheers,
~Al

If you want to image, the larger your aperture, the better your mount's tracking ability needs to be.

At small apertures (say 3" or less) planetary images will be pretty much produce a small dot. If you then use a Barlow to increase magnification, unfortunately you have a larger dot but it'll be moving all over the place without some kind of tracking. You can hand guide but my guess is that anyone will very quickly tire of that.

Dobs and imaging only go together if you invest in a motorised dob mount. They can be bought but I know the high end ones are in the thousands of dollars range...

Its a real bummer for the reason you state - dobs are cheap.

Sorry this couldn;tbe more positive...

Dave

Hi Al

You might want to have a word with Michael Scully of Kerry Astronomy Club (mjs on these boards). He has an 8.75" dob on a home made equatorial mount and does a lot of imaging. check out KAC website
www.kerryastronomyclub.com for his pics of planets with dob and webcam

Albert,
If you went for something like a dob, I do think you'd still be able to do some planetary imagine, just make sure its stable and out of the wind,
I personally would got for as big as scope as you can handle/carry/afford
You can always step it down for planetarey imaging if need be.

As for deep sky imaging, you do need a good mount Like Dave McD said, but once you have the scope, the tracking mount is something you can add on later in the future.

You cant beat aperture, go for the biggest affordable scope, i.e. a Dob.

Albert,

As Trevor said above I do my planetry imaging with my dobsonian but I have built a "Poncett" tracking platform for it. This allows some degree of tracking, sufficient for planetry imaging but not really deep sky. I have two examples of my attempts at deep sky on the www.kerryastronomyclub.com/gallery-deep.htm page but the trailing is very obvious.

I tried planetry imaging without the tracking but it is so difficult to place the image on the small webcam chip, then to focus it and to end up with an AVI where the image marches accross the screen in a couple of frames . It was so frustrating that I gave up and started on the tracking platform. All the planetry images on the http://www.kerryastronomyclub/site are with this setup.

Lunar imaging is ofcourse easy with a Dob using eyepiece projection and prime focus methods.

John Dobson said, "Why do astrophotography when you can get better images from NASA etc for less than the price of the film! It is better to see the wonders of the universe with your own eyes" (or something like that) While I do not totally agree with this it does have some merit.

Michael

Those are good DSOs you have on the KAC site Michael. well done.!