A-1 mystery pin in lens mount

[kl122007]

<p>Just playing A-1 after fixing it, I notice there is a pin in the lens mount, besides the battery house.<br /> What is that pin for? I don't seen it in my old F-1, a hold on the mount instead.<br>

Kevin</p>

[ben_hutcherson]

<p>That lets the camera know that the installed lens is set to the A setting. The aperture ring on lenses pushes a corresponding pin out when moved to A.<br>

The F-1 just has a hole there because it doesn't need to know whether or not the lens is set to A, but still needs to allow the lens to be set there for use with the Servo EE finder. The FT, FTb, TX, TLb, and related cameras don't even have a hole there, making it physically impossible to mount a lens set to A on these cameras, or to move the lens to A while mounted on one of these. All of the A series cameras, as well as the EF, all T series cameras, and the new F-1, have a pin there.</p>

 

[cadillacmike]

<p>Except for the AT-1 - that was a manual camera. However I think Canon was saving some money on assemblies because I saw 2 AT-1s with identical lens mount plates to AE-1s. wierd, because if you put a lens on A on an AT-1 you get F22 (or smallest aperture) and whatever shutter is on the dial. usually results in underexposure.<br>

Later A-series AL-1 and AV-1 were aperture preferred and conversely should also not have the little pin nor should they even have the hole!</p>