JCDowdy Posted June 4, 2016 Share Posted June 4, 2016 Timber, I believe you solved the riddle of this Tokina lens. Good eye! The flange focal distance, or register depth, of the Pentax M42 screw mount and the Pentax K bayonet are the same at 45.46mm. Here is a blog post with a nice photo of the various adapters which comments on this very issue. Link to comment
JCDowdy Posted June 4, 2016 Share Posted June 4, 2016 In Kyoei/Kuribayashi and similar lenses, focusing mechanism moves the entire optical assembly. Alex,If you do not mind, could you please confirm this? None of mine seem to. The lens stays the same length, front element does not move only the rear element moves. I was also under the impression that these were 5e/5g, but I have not dissected one yet. WRONG - see answer below. Link to comment
Alex H Posted June 4, 2016 Share Posted June 4, 2016 I have posted this picture before in a different context, so please ignore the presence of another lens in it. http://ultravioletphotography.com/content/uploads/post-29-0-61159700-1412525813.jpg 35mm W. Acall Kyoei on the right side - the entire optical block was removed from the focusing helicoid. There is no way the rear element can move without the front element moving with it. Link to comment
JCDowdy Posted June 4, 2016 Share Posted June 4, 2016 Thank you Alex, I stand corrected. I was looking at it wrong, the lens does change length. I was looking for the front element relative to the front of the lens - DOPE Link to comment
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