What do I need to connect my xsi to a telescope? and where can I get one?  Thanks.

 I have the XSi also. Need to know what type of scope you have and also what type of focuser.Minimum you will is a T-ring adapter that would connect the camera to the focuser. The are fairly inexpensive.

T=ring adapter

If your scope will accept a 2" adapter then I recommend this one to prevent vignetting.

2" adapter

Scroll down to the bottom of the page to find the Canon adapters. Thes are a bit more spendy though.

JJ

I don't have a scope.  I had one last year but no slr camera.  Now I have an slr camera and not telescope.  What would be the cheapest telescope I could get to get good photos.

Wow Astro Photography is in no way inexpensive. First you need a good optical tube designed for AP. Then you need a guide scope and camera. A sturdy mount to put them on. A laptop or
PC to control it all! Software to process your images. As you can see things add up in a hurry.

An optical tube $400

A guide scope and camera package $410

A sturdy mount that can be guided $1150

See right there you already have about 2 grand into just the basics, and this stuff is the minimum you could get away with in my opinion. I under stand peoples enthusiasm to just jump right in and  start taking those beautiful pictures they have been seeing. I have seen in the last 2 years here on this web site a trend of every body thinks they can do AP right out of the box. It takes a lot of determination and money. I won't mention how much frustration goes in to it also. So I am not trying to be negative with you but I am letting you know up front what you are getting in to. If you truly want to do it Then I wish you luck and I admire you enthusiasm. 

JJ 

JJ

I understand how expensive it is but I took some good shots when I had an advanced point and shoot camera and a cheap tasco.  I might just take moon shots.   What would be a good lens to take shots of the moon.  I will be getting a 55-200mm.  Would I need a 300mm?

Here was my first saturn photo I did with a sony cybershot advanced point and shoot and a cheap tasco telescope

 Mary

I guess I misunderstood your AP intentions. With a camera like the XSi, I thought you were leaning towards doing Deep Space Objects. A camera like the XSi, is kind of large and heavy to be shooting Afocal through a telescope eye piece. The cyber shot was probably better suited. If you cam piggy back the camera on an inexpensive telescope and use your 55 - 200 lens you will be able to take some very nice wide field shots. I would say experiment with the lens you have now before making any more monetary expenditures. 

With even an inexpensive telescope and mount and an Afocal camera bracket, you should be able to get good Moon and planet shots.

Camera Bracket

Then with a smaller telescope and mount with "tracking" you could piggy back the camera and take short wide field exposures of the Milkyway. Maybe a scope like this.

 102 mm Scope

JJ

Thanks those telescopes look nice.  So I would need a tripod for thoose too right.   I don't know about piggy backing.   I think it would take a long time to get into deep space photography.  I'm just interested in the moon and planets right now. 

 That Scope is a complete package. It comes with Optical tube, Finder scope, Mount and tripod. All you would need is the camera adapter bracket mentioned earlier.

JJ

you can use a tripod for lunar shots, id suggest a 66mm or 80mm ED to get started, i would get one that has a threaded focuser for a T-adaptor- i dont know what you have in mind for the planets. but they usually require aperature and a long f/l to get anything half decent- but this is using a planetary imager- not a DSLR, so dont get your hopes up very much for that, im afraid your stuck with doing lunar shots from a tripod as it stands right now- the two types of scopes i mentioned with get you started for AP, as long as you have a decent EQ mount

I suggest you read the following post by Tim Kerr.  It sums up what is required for astrophotography quite nicely

http://cs.astronomy.com/asycs/forums/p/19319/302121.aspx

I also suggest you take the time to learn all the modes of your camera.  In your other post you asked why you couldn't take a picture at night.  You are going to need to switch the mode of your camera to something like "Tv" or manual mode, set the ISO to 400, and the exposure time to around 10-15 seconds.  You won't be able to go any longer until your camera is on some kind of equatorial tracking mount.