On 08/10/10 04:33, John Wild wrote:
James, Belatedly responding to your query; from memory (I do not have any of my 3000 lenses in front of me), the QBM IV lenses have a groove around the circumference of the mount. The groove depth gives the maximum lens aperture information to the camera metering system.
John:I think that I now understand this enough so that if I had a lens in hand and armed with a caliper that I could tell a QBM III from a QBM IV.
Still looking at pictures and trying to figure out what to look for in a photo. That attached photo shows the outer retaining ring on the rear of a Planar 50/1.8. Is that small step in the retaining ring what I should be looking for?
-- James Tyrer Linux (mostly) From Scratch
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