Prime focus question

Hi everyone,

I have access to a 1.2m telescope at my university and i'm looking into prime focus mounts. After reading a little i'm curious if there is a mount that can take advantage of the magnification that various eye pieces provide? And/or if it's worth it? (image quality etc). As I understand, the prime focus mount (2" in this case) will not allow any extra magnification. Is that correct?

Lastly, does anyone have recommendations for T-rings and camera--> telescope adapters? I'm looking to keep it fairly cheap as I just want to experiment first.

Thanks

Can you be a little more specific on the type of scope you have access to and what camera you will be using ? At prime focus (PF) your magnification will only be what the mag is for that particular scope basics are . There are different ways to mount a camera to a scope if using a DSLR then you will need a T-Ring , and what ever adapter you choose for imaging . There are adapters that use an EP (eye-piece) inside the adapter and there are adapters you do not use EPs' with . I have a website with different camera attachments and adapters so you might check it out and see what kind of adapter you want to use .

http://home.grandecom.​net/~r.hodges/equipmen​t.html

I'm fairly certain it's a 25.4cm refractor, I will be using a 7D and/or T2i. It's an old scope, this is at the Cronyn Observatory, Western University (previously the "University of Western Ontario," lame name-change lol). Also since it's in the city I probably wont be expecting amazing results... not sure though.

Allan.L wrote in post #15638384
I'm fairly certain it's a 25.4cm refractor, I will be using a 7D and/or T2i. It's an old scope, this is at the Cronyn Observatory, Western University (previously the "University of Western Ontario," lame name-change lol). Also since it's in the city I probably wont be expecting amazing results... not sure though.

ok a 25.4cm scope = 10" which is a darn BIG for a refractor ! Depending how you will hook it up to the scope depends what adapter you need but for sure you will have to have a T-Ring for any adapters to attach to the camera . The T-Ring you need is the T-Ring for Canon EOS Cameras . And then i use a CA3 - 2” Camera Adapter from Stellarvue . You can insert this adapter into a 2" diagonal or take the diagonal off the scope and insert it directly into the Focus Tube . It serves 2 purposes with one adapter . Good luck and post some picts if and when you get them .

Edit: Got to thinking on the way to work that some of those big scopes mainly refractors have a 2.5" or 2.7" focusing tube so before you order an adapter you need to find out what size the Focus Tube is . The T-Ring will be the same regardless .

Thanks for the info! I'll double check the size, 2" sounds right though. Could you show me an example of something I could use the eye pieces with? I would need some sort of "Eyepiece Projection" adapter along with the other stuff correct?

I'll go in an get some more details about the scope soon, that would probably help my decision making

Celestron wrote in post #15639494
ok a 25.4cm scope = 10" which is a darn BIG for a refractor ! Depending how you will hook it up to the scope depends what adapter you need but for sure you will have to have a T-Ring for any adapters to attach to the camera . The T-Ring you need is the T-Ring for Canon EOS Cameras . And then i use a CA3 - 2” Camera Adapter from Stellarvue . You can insert this adapter into a 2" diagonal or take the diagonal off the scope and insert it directly into the Focus Tube . It serves 2 purposes with one adapter . Good luck and post some picts if and when you get them .

Edit: Got to thinking on the way to work that some of those big scopes mainly refractors have a 2.5" or 2.7" focusing tube so before you order an adapter you need to find out what size the Focus Tube is . The T-Ring will be the same regardless .

You may well find you don't need additional magnification, unless I guess if you're thinking of planetary images you might still want a bit. But if the scope is what you say it is then its focal length will be at least 2500mm (which would be f/10 on a 254mm refractor - those old refractors are more commonly f/12- f/15). That would give quite a narrow field, especially on a crop camera.

How much magnification are you after? A simple method to attain 2 or 3X over the prime focus image is with a Barlow, or, perhaps easier, with a 2Xconverter on your camera before you attach that to the T-mount. And, given the typical f-rations (per Mark), your focal length would typically be 3 ~ 3.8m. Add a 2X to that and... Take Jupiter for example, at 6 or 7m focal length you're getting 3 ~ 5 mm images.
Am.

For some reason I keep thinking its focal length is quite short, 1.2m comes to mind but that might be a different telescope i'm confusing it with. The actual telescope is quite long so my figure it probably off. I'm going to get down there soon and report back.

Here are a couple of links for DSLR adapters for telescopes that may be of value.

Telescopes Adapters

Also their FAQ about different adapters

Thanks Jimmy. I talked to my dad tonight, he's not 100% sure but he seems to think the tube could be ~10 feet, maybe 12, so you're estimates of 3-3.8m focal length are spot on. I think he said it had about a half degree field of view... not sure if that depends on the eye piece used or the objective. Prime focus is all i'll need to start, we are going to try to borrow a t-ring and tube from one of his friends. The telescope was built in 1940, talk about old. Now to wait for a clear night! I'll definitely report back soon.

See Allan if this helps:
LINK