EF -> telescope?

I have a reasonably good mirror telescope and can borrow my friends' lens-based telescopes. Are there any adaptors I could use to get these lenses to work using EF and MF?

1200mm f/5.6 L eat your heart out!

T-ring to 2 inch visual back. PFCT or AP16T from Astro Physics works quite well.

Skip the mirror optic. Too much scattering of light. Although they sound good in terms of mm reach, they leave MUCH to be desired. Go for the high end refractor instead.

Which lens based telescope does your friend have?

I've tried my 40D (and most of the rest of my cameras over the years) with my Meade ETX 90. Its the first generation model, and it takes a T-mount + body mount adaptors. It works pretty well. But, my motor on my ETX 90 died and I need to take it in for repairs... Also, modern bodies are much heavier than film backs, make sure you strip it down for weight... I took off my grip and it still was weighing the telescope down, so I need to find some kind of support brace to mate the body to the field tripod.