BR-2 - BR-2A - Difference

Joined
Jul 22, 2021
Messages
3
New to the forum. Joined firstly to share two images and answer the BR2 / 2A difference question definitively, since I can't find an answer anywhere online. I know this is an old topic but thought this might be useful. I've been surprised by people suggesting there's no difference, or that they can't see one. I had my suspicions so I bought a 2A, which arrived today, and compared that with my BR-2, which definitely will not fit my Df. The two rings are very different in whether they clear the internal mechanisms of newer cameras. The bayonet lugs on the 2A have been milled off at 45º to take away the corner that does hit the electrical terminals that connect with AF lenses, and even after removing one of those the ring still doesn't want to go, so there's possibly other stuff going on at the micro level. You might get away with it on some newer cameras but not all of them. Here's the shots - 55mm Macro at f5.6 on a Df to give enough DOF to show the diff. clearly. Look at the top ring. If you have a lathe or know an engineer, it's a simple job to modify a BR-2 to fit anything once you work out where the problem is. I plan to experiment until I crack this one. Hope someone still alive finds this useful - all my glass is ai or ais!
 

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Joined
Jul 22, 2021
Messages
3
They both should work. The F mount itself is now 62 years old and has not been changed.
Should, but definitely don't! The F mount itself may not have changed but tolerances in the newer cameras definitely have. The mount isn't the issue - the other stuff inside the camera is. I'm sitting here with the two of them and a Df. The A fits, the non A gets maybe 1/3 of the way in and stops dead, like it's saying "Don't push it dude .." It really does not want to go any further and I can see it's hung up. This issue has clearly been stumping and annoying people for decades. I just wanted to help people avoid forcing them on advice from someone who may have had one fit on something it "shouldn't" and facing a busted camera and a large repair bill. Just for kicks I took a file to one of the three lugs on the bayonet of a BR-2 and bevelled the corner off it, cleaned off the filings and aligned it in all three positions. It still won't go, so the tolerances are extremely fine and the ring itself may also be a thou or two thinner to make the clearance. It may even be hanging up somewhere other than the contacts that I haven't spotted yet. All my P and ai/s lenses fit absolutely perfectly, so I have to acknowledge that Nikon know what they're talking about, not that I doubted that. If I had my micro measuring stuff with me I'd take some readings, but to the naked eye even at high mag it's hard to discern, which is why so many people are confused. I've edited my original post to reflect that I still haven't quite figured out what the fine detail in the difference is.
 
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