Currently there seem to be two types of Exacta to Eos EF adapters available - one type is cheap, a simple converter that is recessed slightly into the camera mount and (just) allows focusing to infinity by the lens flange being more or less level with the front of the camera, the other has the lens well out from the camera body and presumably incorporates a corrective lens - it's a lot more expensive. Until a few days ago I would have recommended the cheap ones unreservedly - they work very nicely with manual stopdown lenses. But I've just had several lenses in with Exakta's version of auto-stopdown, which has a stop-down button in a side housing, and it turns out that it is impossible to mount lenses as they're supposed to fit. An example of the type of lens below: The adapter fits onto the lens before you put it onto the camera, and goes in with the side lump at the top. Except it doesn't because the bit that sticks out fouls the flash. It is possible to put them in at a different position, but then they don't lock on properly, and I think that there's a very good chance that they could get jammed and be impossible to remove without damaging the camera. It looks like the adapters with lenses bypass this problem, though there's probably some degradation of the image, so they may be a better option if you're really keen to use Exakta lenses.
Update on this - it appears that there are two slightly different designs of lensless converters. One (the type I have) is black and has a round groove going round the full circumference of the mount (to accommodate the locking pin on the lens) and has one clip to hold in the lens so that the numbers at the top - the other is silver and has two grooves each of about 45 degrees, and from what I can see it LOOKS like it's designed with two positions for the lens to lock in, one with the numbers at the top, the other with the lens rotated through about 60 degrees so that it doesn't foul the mirror. They're fairly cheap and sold from the UK, so I'm going to try one and see how it compares, then sell one of them on.
OK, got the other one today, it does pretty much what I thought - if you have a manual lens that doesn't have the part that sticks out you can use it with the numbers at the top, if you have an auto lens it goes on with the locking pin in the other slot, ends up with the lens round about 90 degrees from the top near the hand grip, so that it's quite easy to stop down just before taking the picture. The only problem so far is that it's a VERY tight fit, takes a lot of force to put the mount onto a lens. I might give it a rub with emery cloth to make it very slightly looser, though with my luck it could be five years before I see another Exakta lens... Meanwhile I'm selling the first one off, starting at £1.99 on eBay UK, see Classifieds for details.
