[simon_199]

Hi,

i am in possession of this lens, actually i am the one who added it to the list, since it wasn't present in the database, so those are photos of my actual lens.

Petri 50mm F1.7 MC Lens Reviews - Miscellaneous Lenses - Pentax Lens Review Database

This came with a Petri camera bought by my father a long time ago, and i have used it pretty extensively on my k200d. It appears to have a standard K-mount (at least i always inferred so, since it worked fine). For sure there is no Ricoh pin, i attached a photo of the mount itself. (taken with the cellphone, excuse for the crappy quality).

The problem is that on my new K-3, the lens won't stop down when pressing the green button. While, as i said, it worked fine on the k200D, and other manual lenses such as the XR Rikenon 28mm work fine on the K-3 ! So i guess this Petri lens might have some sort of "not exactly K-mount compliant" aperture lever geometry that might work or not depending on the camera body ?


I think it's a pretty rare lens so i expect no one with experience with this specific specimen, but there are tons of third party (non pentax) K-mount lenses around and i am wondering if anyone has experienced such a behavior with any one of those, and if there is a possible solution.

One is just to use the lens only wide open in Av mode...


Thanks in advance for any help or feedback

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Last edited by simon_199; 09-04-2015 at 01:23 AM.

[Adam]

One is just to use the lens only wide open in Av mode...

You need to put your camera in M mode, then the stopping down should work just fine.

https://www.pentaxforums.com/forums/54-pentax-lens-articles/110657-how-use-me...k-x-k-7-a.html

[Joojoo2010]

https://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/290902-h...nts-again.html

[simon_199]

You need to put your camera in M mode, then the stopping down should work just fine.

https://www.pentaxforums.com/forums/54-pentax-lens-articles/110657-how-use-me...k-x-k-7-a.html

I know that, when stating that stop down metering doesn't work i was already referring to M mode In Av mode it works with full time metering wide open just as my other M lenses.

Interesting suggestion about the lens not making contact ! The lens body is made of metal but maybe the black coating (anodizing or paint, whatever it is ) is preventing the lens to make proper contact with the camera body...maybe i'll investigate on that....

[marcusBMG]

more discussion of this:

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

[Lowell Goudge]

You need to sand the paint off the mount in the area of the contacts. Pentax changed their software at some point I. Time (camera model) to require for no A lenses that the data pin be shorted,

My K10 is fine(same age as K200) but not my K7

[virgilr]

I seriously wish the firmware would be modified for post k20 bodies so the aperture pin short isn't required! I don't want to be sanding anodized metal on mounts- I've used aluminum tape and made a template but even that is a hassle since the tape can wear/tear and metal bits can fall into the body. I want to keep the lenses in good shape for possible resell in the future. K100ds fine, k30 nope!

[simon_199]

Thanks for the information to everybody. I used the search function but i was not expecting a similar explanation (i thought lack of contact pins = recognized as M lens) and didn't search the right things :P

Maybe i'll modify the lens finally, but most of the times i use that lens is to shoot wide open, so Av mode works fine without stop-down metering...

[Lowell Goudge]

I seriously wish the firmware would be modified for post k20 bodies so the aperture pin short isn't required! I don't want to be sanding anodized metal on mounts- I've used aluminum tape and made a template but even that is a hassle since the tape can wear/tear and metal bits can fall into the body. I want to keep the lenses in good shape for possible resell in the future. K100ds fine, k30 nope!

Unless they are BNIB the next purchaser will need to do the exact same thing unless he is a collector, and that does not really appeal to third party bargin lenses. I don't consider resale value, I consider using the lens

[virgilr]

It's not just resale value though it's the hassle. You can't just "sand off" anodization. I modded an m42 lens for av mode to work that was anodized and had to use a wire brush on my dremel very carefully since the aluminum mount is quite soft.

[stevebrot]

so the aperture pin short

I believe that should be the data pin that requires shorting...




Steve

[stevebrot]

but not my K7

??? I was aware of the CIF and Focus confirm issues with the K-7 and non-conductive bases, but thought the lack of green button stop-down followed the K-01 >> K-30/K-50 >> K-5II/K-5IIs >> K-3 lineage.

Edit: I reviewed Marcus' post above and am a little confused at this point, perhaps because the lack of posts regarding anodized k-mounts and the earlier cameras such as the K-r.


Steve

[stevebrot]

I seriously wish the firmware would be modified for post k20 bodies so the aperture pin short isn't required!

I don't believe the issue goes back that many years. The first I heard of it was with the K-01. Edit: See edit on my post above.


Steve

[Lowell Goudge]

??? I was aware of the CIF and Focus confirm issues with the K-7 and non-conductive bases, but thought the lack of green button stop-down followed the K-01, K-30/K-50, K-3 lineage.


Steve

I can't go back and check now because the extension tubes I have, I modified. Too late to test the whole limit if functionalities

[marcusBMG]

I can confirm the K-r doesn't stop down with the green button if the mount is non-conducting.
I intend to update that piece on the k-r with how my K5 works as well: much better basically!