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07-09-2013, 04:06 PM   #1
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Lenses without Auto/Manual Aperture switch

I recently purchased a couple of Yashica Yashinon lenses (DS and DS-M, M42, 50mm/1.7's). However, neither has an auto/manual switch. Turning the optical preview on (i.e. turning the power button) does not show any difference in image though the viewfinder regardless of what aperture the lens is set to. What am I missing here, and how can I use these lenses. Is this a case where I have to modify the lens so as to keep the pin depressed? Thanks.

07-09-2013, 04:13 PM   #2
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M-42 lenses must be in manual to operate with digital. I only buy those that have an A/M switch so I'm not experienced with correcting an auto only lens. But if you search for m42 auto manual switch you should find a number of threads on this subject.

Here is your other thread: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/229022-modifyi...-m-switch.html Which I think answers your question. If not, then I guess I am not understanding you.
07-09-2013, 04:14 PM   #3
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The pin will have to be gimmicked to keep it depressed. Or you can gimmick the adapter, or just buy an adapter that already has the inner rim...

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/51749-m42-auto...ification.html

jr-worldwi.de: Photography: Technic
07-09-2013, 09:12 PM   #4
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QuoteOriginally posted by jatrax Quote
M-42 lenses must be in manual to operate with digital. I only buy those that have an A/M switch so I'm not experienced with correcting an auto only lens. But if you search for m42 auto manual switch you should find a number of threads on this subject.

Here is your other thread: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/229022-modifyi...-m-switch.html Which I think answers your question. If not, then I guess I am not understanding you.
Thank you for your response. Yeah, my question was whether that was even necessary in the first place. Now that it looks like it is, then i can go to that other thread. One other question: to remove the aperture ring, do you remove the three small screws directly above the ring? I don't see any screws on the mount face, so I am guessing those are the ones.

07-09-2013, 09:22 PM   #5
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QuoteOriginally posted by toukan Quote
to remove the aperture ring, do you remove the three small screws directly above the ring?
Not familiar with that brand of lens, Takumars I can take apart but never had a Yashica. Take a look at this thread: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/180765-yashica-lens-question.html
07-09-2013, 10:25 PM   #6
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There are 2 options, one is to do a quick mod to the lens to force the aperture pin to be always depresses, the other is to use an M42 adaptor with a lip at the bottom to depress the pin.

The mod looks like this,


I use a small snip off the end of a ball point pen refil. It is just the right size

The adaptor with a flange is available from B&H in New York .
General Brand Pentax-K Body to Universal Lens Adapter ABPKS B&H
Be careful though with the adaptor. The screw which holds the little spring on is usually too long and can cause the lens to bind in the threads, and the spring can sometimes deform making it difficult to get the adaptor off. Many people just take the screw out and leave the spring off all together.
07-11-2013, 01:18 AM   #7
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Hi,

one thing you need to do before using these lenses is to permit the use of the aperture ring (for lenses without an A position). In a K5 you will find that in the C 4 Menu Nr. 27, in a K20D it will be Nr. 36 in the C Menu.

Or take a look at the first sticky in this forum about the use of manual lenses.

Last edited by joe_c; 07-11-2013 at 02:39 AM.
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