EOS-3 and M42 adapter (giving me BC error)

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Bill
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I have tried fitting an EOS-M42 adapter onto my EOS-3 to use my Super Takumar lenses on it. Works fine om my 20D, but on my EOS-3 I just get the mirror locked up and a 'BC' error. its close to the mirror but does clear, any ideas why it doesn't want to play nice???
 
Hmm. Can you tell us more please: does your adapter have a focus confirm chip or is it bare metal? How does it feel when you fit it to the EOS-3? (I don't know this camera and I'm assuming that the lens contacts are the same in number and position as on your 20D? Is the problem before a lens is fitted and what happens when a lens is fitted? (Some manual focus lenses do foul the mirror on focussing, in my experience when you shift focus out towards infinity.)
Do you get shutter release which then stops partway through or can you not release the shutter?
 
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Yep - i've got an idea. There's a switch built into the mount for the lens



Some adaptors need the switch to be held open, some need it to be left closed. If you're getting the error, then your adaptor needs it held open. Take a small piece of film canister material and a pair of tweezers and wedge the switch open.

It's all down to the length of one of the bayonet tang's in the adaptor. I've 2 adaptors, one of them had no AF confirm chip fitted and needed the switch wedging open. The other had an AF chip and the tang was longer and held the switch open itself



(ignore the remove metal from this end bit - it was instruction for someone else's badly designed adaptor!)
 
Cheers TBY. I cannot find the adapter at the moment but if I fire it with no lens on its fine, if I wedge the little switch open with no lens and try I get the same 'bc' error, so once I find my adapter I'll get the files out and let you know how I fare :)
 
to check if you need to get the dremel out, attach the lens to the adaptor, and put the adaptor on the camera but don't fasten it all the way closed (i.e. it doesn't click into place.) Support the lens in place, and do a test fire of the shutter. If it works, then just take a little off the adaptor tang where it's marked blue and in the green circle. Obviously, it's also essential to get the adaptor scrupilously clean afterwards - especially if you're going to use it on the digital as well - don't want swarf in your sensor - or indeed anywhere else. I used a spray can of electrical contact cleaner to ensure that nothing untoward was left behind after working on it.
 
trimmed it back but it appears the problem is the EMF AF confirm chip as well! taped over that and all is good so I just need a dumb M42>EOS adapter for this camera.
 
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