I just recently bought my first DSLR, a Canon Rebel t2i/550d. I use it mostly for video and it works wonderfully. I bought the kit lens with it, but I am looking to expand my lens collection. I found a set of old Minolta lenses from my dad, and I was wondering if I could use them on my new camera. The lenses are: a Sigma UC zoom 28-105 f4-5.6, a Minolta Maxxum zoom 70-210mm, a Minolta Maxxum zoom 28-58mm and a Kalimar 500mm lens. I know about the crop factor and that the auto focus won't work, but that does not bother me. Is there an adapter for Minolta AF/Sony to Canon EF mount? Any help is appreciated. Thanks!
No. The six SLR mounts that you can easily adapt to Canon EOS with simple ring adapters are Leica-R, Nikon F, Contax/Yashica, Pentax K, M42, and Olympus OM.
But Minolta AF lenses work just fine on Sony Alpha (A-mount) dSLRs and dSLTs without any adapters. And you can, of course, adapt these to mount on the Sony E-mount (NEX). But not for Canon EOS.
When adapting between mount systems, the registration distance is key. This is the distance at which the lens is held from the image plane, and it has to be maintained to focus as designed through the full distance range to infinity. So you typically can only adapt from a system with a larger registration distance to a system with a smaller one; because shoving a lens farther back into the body usually isn't possible without physically modifying the mount itself, and adapter rings always add to the distance.
With Minolta AF (44.5mm registration) to Canon EOS (44mm registration) adapting it's not that Minolta AF's registration distance is smaller, it's that it isn't large enough to practically machine an adapter ring to overcome the differences in the bayonet flanges. 0.5mm it too thin for a metal ring to hold up reliably (same problem with Leica R->Nikon F, btw.)
You can adapt from a smaller registration distance to a larger one without replacing camera or lens mounts if the adapter includes a glass element to act as a short teleconverter so the lens can still focus to infinity. But that teleconverter will affect the image quality--especially if it's low-cost--and this won't be ideal. It will also decrease the max. aperture, and increase the focal length of the adapted lens.
And there's one other problem. You need an aperture ring on the adapted lens, because while you can physically adapt the mounts to fit, there isn't going to be any electronic communication between the lens and the body. If you're adapting a lens without an aperture ring (and Minolta AF lenses are like Canon EOS: no aperture rings), then you'll be stuck shooting wide open all the time.
And without electronic communication you have no autofocus, no aperture control from the camera, and no EXIF information from the lens (e.g., focal length, lens name, max. aperture, etc.) Canon bodies, however, can perform stop-down metering if they sense there's no electronic communication from the lens, so you will at least have accurate metering if the lens actually stops down with the aperture setting. You just have to get used to a dimmer viewfinder. But you will be limited to shooting in M or Av, since the camera won't be able to adjust aperture.
There is different way to adapt lenses designed for one brand to fit another brand of DSLR.
If the flange focal distance of the lens brand is bigger than the one of the body, you can use a lens-less adapter ring (as an example Contax C/Y mount lenses on Canon)
Doing the same with shorter flange distance (as exemple Contax C/Y mount lenses on Nikon) has the effect that you lose the ability to focus at infinity. In such a case you can either:
use an adapter with a lens
replace the mount (see for example http://www.leitax.com)
Those three solutions share the main problem that you will lose the coupling between the lens and the body (Apart from in specific cases such as Contax N1 mount to Canon), which means you will have to focus manually and meter in AV mode stepping down the lens manually.
The usage of an adapter with a ring (as suggested by Mike) has the additional drawback that the additional adaptor (low-end quality) lens will, most of the time, cause bad optical performance. Note also that the distance scale (on the focussing ring of the lens) is no longer usable with an additional lense.
Usually this is enough to discourage the usage of lenses from one brand on another body except for some very good lenses (and only in the cases without additional lenses). See also the discussion on Bob Atkins' site
If you really want to use your lenses I suggest that you replace the lens mount. To see a step by step discussion here, although it doesn't seem easy.
It certainly looks like you can get the adapters - a quick check on ebay revealed this one.
Though I can't verify how good it is, etc...
Yes You can use older Minolta lenses (with aperture and manual focus) on EF mount with the appropriate adaptor ring. Leitax has them. It's true the registration difference between the two is .5mm. Canon 44 & Minolta 43.5mm. But if you look closely at the EF and Minolta lens mount ring, the minoltas bayonet is bigger than the EF so there is an extra 1 or 2mm. To test, try lens whacking the minolta on the EF and you can focus to infinity.
Most adaptors on ebay are too large and whoever made them does not understand registration distance. I wouldn't use one with glass to tele convert either, all you need is the appropriate ring. If you check out the Leitax mount it is actually a couple of mil thick, plenty strong enough.
I have adapted Zeiss/Nikon mounts using Leitax rings, which is a permanent mount, and though expensive they are machined to perfection and just as strong as the original mount. A little patience and some screw drivers.