Hi
I adapt old lenses to my canon 5D. search on amazon PK to EOS adapters.
I adapt old pentax M42 screw mounts and are a joy to use, i find it exiting however a few things need to be said, 1st if canon finds evidence of chipped adapters being used, it invalidates any warranty, as canon don't officially recognise them. So if like mine your 5d is out of warranty anyway, your ok. you can buy non chipped mounts but as i am about to explain why its best to use chipped ones.
2nd even me with young 20/ 20 vision find it painfully hard to get absolute focus (its possible) but because our cameras are designed with AF lenses if you look at the eye peice the lens is shaped like a cinema screen making it blumming hard to focus the lens by eye.
so finally (3) its best to use Chipped mounts, this engages the AF system within the body, so as the lens comes to focus you get the red blink and beep as you do with a AF lens. the down side to this is as i said canon will invalidate the warranty. Also you have to take a risk when first attaching the adapter to the body that it does not short circite the camera which means it stops working, requiring it to go back to canon. The adapters I have bought from Amazon have not damaged my camera at all, they do as they describe, but becouse i have this fear about the web, I found i was not overly confident about putting it on my camera until i did, and the ones i use work, but to get sharp shots really one needs the chip.
so I guess that may have put doubts in your mind, and i don't mean to do that because the advantages are evident, you save money, its really good fun, even if i could afford prime canon lenses I would still do this, because to me im telling canon to ---- off and i will do what i want to do, 2nd getting a unique approach to photography, i get different results from everyone else because of how i do things and that's good.
So if you want to be creative its good, but if you want to lets say, see how useful a 50mm will be to you, you can do this. See how you feel about being limited to a prime ect to then think, you know what, this Christmas ill treat myself to a 50mm 1.4 ect or i really fancy the 24mm 1.4, its a lot of money but the advantages over adapting is 1 you can't put a price on AF and 2 the glass is upto date and new lenses tend to be faster than the old. (therefore your more certain that you'll have sufficient use for the lens when its on your camera, in the feild ect)
ill give you an idea, i bought 2 nikon macro lenses, one is the 55mm 2.8 and the 2nd is 105 F4. now i don't really need macro lenses, Iv always fancied a macro lens but i cant justify spending money on a lens with limited use. (unless I was a multi millionaire and bought it because I could/ or just another toy) i found these for £24 on a market stall and realise that yes there very good, and i occasionally use them but i would not go out and buy one. My god though the 55mm is bloody sharp or as I deem it "deadly sharp"
in the same vain however, what Iv found with my 50mm lens is id like to save up for the 50mm either 1.4 or 1.2, but i first need a job, and unfortunately as a young man i seem to be deemed as "the lost generation" and therefore doomed for eternity to be racing after jobs with (at the moment competing against 500+ applicants each time)
Other lenses I found would warrent buying 24mm 28 35 50 135 and shift lens, that said not yet found a shift lens within my price range.... looking at 35mm 2.8 PC, looking for one not at £300.
Then that said, before i bought any lenses, i would finely buy my first true love, NIKON.
Just to conclude then, yes they work, yes they are very good, you can get unique results from the old glass, its worth the risk especially if your not very affluent/ (that's not to say its not a cool thing to do, being creative/ doing something that canon deem as unlawful is). Its a cheap way to put a certain focal lengths into a real life situation, without the pressures of a salesman ect many advantages but its all down to what the end-user thinks/ wants ect.
By the way my ideal job would be to work with a camera companies, either sales (most probably) or in some other way
I also adapt Nikon lenses as well which are far better quality than the pentax's but are more expensive because nikon users can use them on brand new bodies as well.
So if your wealthy, buy the real thing, if your creative and wealthy do both, and if you poor like me, save money, do it and have fun.
Hope this helps, happy shooting.
PS excuse the spelling, top gear is now on.
Hope this help