need help with Canon XSi and a t-mount

[TerryInLeesburg]

OK, this is probably going to result in a "D'oh" moment, but here goes...

I have a Canon Rebel XSi. and just bought a small telescope for it.
The scope is attached via a t-mount, and is full manual.
When I put the lens on the camera, The camera reports F00 (no lens) and there is no way to change the f-stop to F8 (the f-stop of my scope)?

So, my question is: How do I set the F-stop (presumably in AV mode) with the scope (and the camera showing F00)???

Thanks a lot
Terry

[jimt]

Well, here is the thing, when you attach the camera to a telescope in prime focus, the telescope becomes the lense. The telescope is at a fixed focal length so you can't adjust that. Everything you shoot will be at F8. Yep you guessed it, you have to focus your frame with the telescope focuser. Don't feel bad, I asked the exact same queston, so next time someone asks it, you can answer.

Happy imaging!

Jim

[Canon Pete]

Jim is correct. You lose the f-stop ability, that is on the camera lens NOT the camera. You only need to work with the camera shutter speed.

Clear Skies

Pete

[TerryInLeesburg]

Will give it a try.

For my first photo (probably the moon) what shutter speed would you suggest? Or do I just play? (One of the reasons I love digital - not wasting film )

[jimt]

Just snap some shots and go from there. I shoot the moon @ iso 100 and around 1/500 shutter speed. I might shoot it at 1/1000 Cant remember right off. Just play around with it since you aren't wasting film.

Jim