I have had this Schneider Symmar 135/5.6 for a while now and I have noticed from time to time that the sliding aperture indicator on the Copal #0 shutter gives two different readings depending on whether you look at it from the front or from the side. The section of the aperture indicator that hugs the side of the barrel of the shutter is bent to the right, so the reading from the arrow on the side of the shutter will always be 1/2 stop slower than the reading on the front. (e.g. If the arrow on the front reads 11, the value indicated on the side will be 13--halfway between 11 and 16.) The little metal arrow for the side reading is not affected by the bend in the other indicator, to which it is connected from inside the shutter.
Here are some things that you should perhaps know about the lens:
I bought it used from an advertising company that had used it to shoot slides and they were very straightforward with me about what was right/wrong with the lens, even sending me the appraisal report--in which the bent aperture indicator was not mentioned. (Things that were more serious/difficult to fix WERE mentioned.)
I was never really too troubled about this problem because I was mostly using this lens to shoot B&W,with which I always over-expose a stop anyway. The B&W negs I have shot using this method look nicely exposed and have good shadow detail with no push/pull. Even when I shot color with this lens and consistently used the reading on the front, I did not detect any significant under-exposure. But I never, in fact, bracketed exposures 1/2 stop apart to check. I scan all my LF film for printing, so one stop doesn't usually make a difference. Now, however, I am shooting slides, so I want to eliminate any possible exposure variables that I can take care of.
With the front arrow set to 5.6, the aperture width is about 16mm. With the side arrow set to 5.6, the aperture width is about 18.5mm. With the blades wide open, you get close to 24mm. (But that seems wrong. Why should the ratio of focal length-to-aperture width only reach 5.6 when the lens is wide open BEYOND its usable limit? I thought the whole idea with a lens like this was that you got 4.0 or 4.5 for focusing, but that the widest useful aperture was achieved when the lens was stopped down a little. So a lens marked f 8 can actually be focused at f 5.6 and so on. Here, regardless of whether the indicator arrow is bent or not, you get to the point marked f 5.6 on the shutter only when you stop down a little, but arithmetically you only get f 5.6 when the lens is wide open. Or am I missing something?)
Or maybe the bent arrow is supposed to be like that? Somebody changed it to compensate for some other mechanical error that was interfering with the aperture indication?
Any advice would be greatly appreciated.