I got a couple of pretty good lenses on eBay. Both lenses have M42 mount. There are many options available on eBay for these mounts as well but my concern is not only to make sure that the adapter will work properly with the lens, I would like to make sure I can take it off the camera as well if for some reason it's not easily removable. Are there any recommendations whose adapter works well.

I even check out the one with the link below but at the same time because of the thickness, I am concern about how it effects the optics. All your suggestions are really appreciated.

AF Confirm M42 Lens to Canon EOS EF Adapter 550D 50D 7D - eBay (item 270642657714 end time Oct-29-10 21:19:47 PDT) (http://cgi.ebay.com/AF-Confirm-M42-Lens-Canon-EOS-EF-Adapter-550D-50D-7D-/270642657714?pt=Camera_Lenses&hash=item3f038f39b2)

I use Nikkor to EOS adapters from Kawamall on eBay and they have been excellent. I have 5 of them for my Nikkor lenses. All are made of bronze, chrome coated. I had ordered a couple of $40 adapters from photo store and sent them back because one was too tight, the other wouldn't go on at all.

Pentax M42 Lens to Canon EOS 20D 350D 1d 3 30d adapter - eBay (item 290483971688 end time Nov-04-10 00:50:39 PDT) (http://cgi.ebay.com/Pentax-M42-Lens-Canon-EOS-20D-350D-1d-3-30d-adapter-/290483971688?pt=Lens_Accessories&hash=item43a231a668#ht_4198wt_1167)

Presumably the M42 adapter would be as good. They're cheap enough to buy and try out.

What you do is mount one on each lens. Then the lens will mount and unmount to the camera quickly and easily.

Thanks very much, I've ordered three of these adapters.

I use the Kawa for my M42 and Nikon lenses. Shoot with them every week. No problems.