Why I can't find an A-mount to Canon EF Adapter?

Question

I looked online for an adapter from A-mount to Canon EF but I couldn't find. The Minolta/Sony A-mount flange focal distance is 44.50mm and Canon EF flang focal distance is 44.00mm, in theory A-mount lenses can be used with a proper adapter on Canon EF system, but I can't find one, I'm curious why?

Asked by Akram Mellice

Answer

First of all, this leaves only .5 mm for the adapter, which isn't a lot. With a mount that's a lot smaller in diameter most of the adapter could sit inside the EF mount ring, and you could probably do it. From what I recall of the diameters, they're similar enough that this would be extremely difficult, if possible at all (and I'm leaning toward "probably not possible").

Second, EF mount uses an electronic connection for both aperture and focus, where A mount uses a mechanical linkage for aperture, and either mechanical or electrical for focus (but electrical was introduced relatively recently, so most older lenses being adapted would probably be mechanical).

Since (most) A mount lenses don't have aperture rings, you'd have to build an aperture control into the adapter. If it was purely mechanical, you could do stop-down metering. In theory, an adapter with some sort of built-in servo could receive the electrical signals from the body and translate them to mechanical movement for the lens. Given the small difference in flange distances, neither of those would probably be simple or straightforward -- but without it, you'd have no aperture control, so you could only shoot at the lens' minimum aperture (typically f/22) -- pretty useless. You could build a fixed stop into the adapter to always hold the lens at, say, f/8 I suppose, but it would still be quite limited, even at best.

Answered by Jerry Coffin

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Can I fit a Minolta 35mm lens to a Micro 4third mount?

Question

I have old 35mm lenses for my old Minolta camera. I'm going back to photography and getting an Olympus PEN E-PL1 (micro four thirds mount).

Can I use my old lenses on such a box or do they become completely useless? They were pretty expensive lenses, so why throw them away?

Answer

There are a number of adapters for Minolta MC/MD to Micro Four Thirds, like this one at Amazon. (If you are talking about Maxxum/Dynax lenses, then look for Sony Alpha to Micro Four Thirds adapters.) The lenses will be all-manual focus and aperture (no automatic stop-down), but you can use them. It's just going to be an old-timey sort of experience in the digital age.

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