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02-15-2016, 06:02 AM   #1
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Can Catch in focus work with reversed M42 lens (K-r)?

Hi,

Per the subject, I was wondering if catch in focus can be made to work with a reversed M42 lens (i.e., M42 lens via a reversing ring). I have a K-r, but I think that this is also a generic question.

I already have the catch-in-focus enabled in the menu, AF-S and focus-priority. The camera is in M focus mode. Obviously, since I'm working with a reversed M42, I don't have an AF/MF switch on the lens.

Thanks,
Jim

02-15-2016, 06:15 AM   #2
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Catch in focus does not work if the camera is set to MF. The camera needs to be set to AF even though the lens is a MF lens.

A reversed lens won't work with Catch in Focus without shorting the pins on the camera. This also applies to many M42 lenses that have narrow bases or non-conductive bases.

You might be able to get away with using a wide flanged M42 adapter (the non-infinity kind) and then a M42 reversing ring.
02-15-2016, 06:37 AM   #3
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Hi,

FYI, I actually am using a kind of convoluted configuration for NOW, using a 49mm reversing ring to a T-mount adapter to an M42-to-K mount adapter.



Separated so you can see the T-mount adapter:



Could I do something like this thread:

https://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/218221-c...ion-k-x-2.html

i.e., make a ring out of aluminum foil like that?

Jim

EDIT: Here's a pic of the whole thing mounted on the K-r:


Last edited by ohaya; 02-15-2016 at 06:48 AM. Reason: Add pic
02-15-2016, 06:52 AM   #4
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I made some comments about this sort of thing here:

https://www.pentaxforums.com/forums/116-pentax-k-r/271872-tests-plated-vs-pai...r-whats-t.html

02-15-2016, 07:01 AM   #5
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Why not get a K-mount reverse ring adapter? They are cheap enough, cover the pins and often bare metal. And a set of step-up/down rings to cover the different filter sizes you may have.
02-15-2016, 07:19 AM   #6
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QuoteOriginally posted by Not a Number Quote
Why not get a K-mount reverse ring adapter? They are cheap enough, cover the pins and often bare metal. And a set of step-up/down rings to cover the different filter sizes you may have.

I don't have a direct 49mm-to-K mount adapter yet. I have one ordered, but it's on it's way, but I made that purchase before I was messing with CIF, and I don't think that that will be wide enough to cover the contacts (see the pics above).

Does anyone know exactly WHICH contacts need to be shorted to which contacts? I haven't found that info yet. I see stuff like "cover the contact that is 180 from the red dot" but what does that contact that is 180 from the red dot have to be shorted TO?

The threads about making a ring seem to imply that if I short ALL of the contacts to all of the other contacts, then that would do the job?

---------- Post added 02-15-16 at 07:43 AM ----------

I did some testing, shoving a metallic piece under the T-mount adapter as I screwed it in, shorting just the one contact pin next to the screw, to the rest of the camera face/mount, and then CIF worked!!

02-15-2016, 07:59 AM   #7
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You just need to short out the "data" pin which is the one closest to the screw-drive - which is what you shorted out. Shorting all the pins (except the "A" pin) doesn't matter one way or the other.
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