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12-14-2009, 09:21 PM   #1
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Help. KPR mount ?

Hi, i have just purchased the following :

Pentax Sigma 24mm Super Wide II f2.8 Macro KA Lens

Pentax Sigma 24mm Super Wide II f2.8 Macro KA Lens on eBay (end time 02-Dec-09 08:24:10 GMT)

Now the box that came to me says :

Sigma 24mm F 2.8 KPR mount.

Is this the item I purchased? Whats the meaning of KA and KPR?

Now i am finding some problems :

- It doesnt lock unless the camera is on Autofocus....if its on manual focus, the lens falls off the camera.
- The A setting does not work, it does not open the aperture blades when inserted into the camera
- A tiny hair shaped dust in the middle element? Doesnt affect image quality, so i am not too worried about it.

If the listing is indeed for this item, then i guess its my fault for not understanding what i am purchasing.
Please help, i need to get back to the seller...or rate him.

12-14-2009, 09:51 PM   #2
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My copy looks exactly like the auction photo except for the rubber focus grip. Mine is a newer style, but I believe both styles were used - my Sigma fisheye has a KA mount and the older grip.

My lens mounts and works fine. The description certainly says that lens ought to mount to a Pentax DSLR, so if it doesn't, it sounds like a full refund is in order if you choose.

Here is my wild theory about your problem. KPR maybe could stand for K-mount, Pentax-Ricoh. In fact, my lens does have a version of the Ricoh program pin. It has always worked fine so I never bothered with it, and I have a couple of other Sigmas with the same setup. Your lens may have an unruly pin. It should be possible to identify and remove the pin if you can take a decent photo of the lens mount.
12-14-2009, 10:15 PM   #3
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Err, so there is a KA mount version? And my box says KPR mount...so i didnt really get the item i paid for, i guess.

Below is the picture.....where is this pin i should be looking for, and what should i do to it?


12-14-2009, 10:41 PM   #4
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Think of it as Sigma's version of a KA mount. Several third-party makers did the same thing, making lenses that were compatible with both Pentax and Ricoh "program" cameras.

My lens looks mostly the same as yours, except my "Ricoh" pin is larger. My pin might be a running improvement so that it doesn't do what your pin might be doing: dropping in the hole used for the auto-focus screw drive and getting stuck. The pin on your lens is on the chrome mount, brass, surrounded by a black insulator and the closest to you in that photo. A nearly identical pin to the right is the Pentax pin.

You have a couple of options to deal with the pin. You can use a Dremel-type tool to grind it down so it is below the lens mount level. Or remove the three chrome screws in the lens mount, the small black screw in the photo below the aperture ring, and remove the mount. You ought to be able to pull the pin out from the inside of the mount. Either way, the lens should attach more smoothly to the camera.

12-14-2009, 11:02 PM   #5
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Ah thanks dave. I think the problem is not the famous Ricoh pin. I see which one it is now. It drops in the auto focus screw, but it pushes right out...so I have no problem of lenses being stuck on the camera.

The problem is, the lens wont lock in camera, unless the Auto-focus screw is engaged, and actually pushing that ricoh pin into its hole. . So this lens cant be used in manual camera mode.

the second problem, is that the A setting does not fire....the aperture blades remain closed. Now you are saying that the pin to the right is the pentax pin? is this the pin for the A setting? Is there a trick for me to making it engage?
12-14-2009, 11:20 PM   #6
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Maybe i misunderstood the A setting...this is my first lens with an A setting after all, that is a manual. The other one is an autofocus lens.

What does the A setting exactly do, and how does it different from a manual lens without it? And how do i use it? I kind of assumed it allows me to control aperture sizes from within the camera.....rather than moving the ring around.
As it is right now, this lens stays at closed (F-22) position.

Thanks again....

Last edited by D4rknezz; 12-14-2009 at 11:30 PM.
12-14-2009, 11:40 PM   #7
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I have found the problem....it wasnt locking into place, because for some reason it was stuck half way into its rotation in the mount.

Wiggling it (a lot, since before it wouldnt do it) for the past several hours did something, and now it will revolve properly to locking position. I am guessing the A setting will now work. It is now locking properly on Manual camera position too.

Thanks for the help dave!
12-15-2009, 12:01 AM   #8
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QuoteOriginally posted by D4rknezz Quote
I have found the problem....it wasnt locking into place, because for some reason it was stuck half way into its rotation in the mount.

Wiggling it (a lot, since before it wouldnt do it) for the past several hours did something, and now it will revolve properly to locking position. I am guessing the A setting will now work. It is now locking properly on Manual camera position too.

Thanks for the help dave!
It stuck because of the Ricoh pin (visible front and center in your photo!)

Steve

12-15-2009, 12:22 AM   #9
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Aaah.

I get it now.
I thought "stuck" means just not coming off the camera.

I didnt think "stuck" could also mean...stuck from revolving and locking into place.

Well, i guess pushing it in and out several times with a knife losen it enough for it to now move past the autofocus hole.

Thanks again guys. also..

Here is a reminder for myself, if i need to do this. Or for anyone with the same problem :

Sears 60-300(auto aperture, push pull zoom): Pentax SLR Talk Forum: Digital Photography Review

I didnt think it applied to me, but now it may.
12-15-2009, 09:26 AM   #10
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QuoteOriginally posted by D4rknezz Quote

I didnt think it applied to me, but now it may.
Hopefully you won't have trouble getting it off.

Steve
12-15-2009, 12:49 PM   #11
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I have a Cosina 24mm f/2.8 with 'A' setting and with the exact P/K-AR mount. As long as you find the Ricoh pin to be retractable as you see on this picture, you should be fine. On your Sigma lens rear mount, you should see two golden contacts, one on the far end is the Ricoh pin where one along with the electrical contacts is probably for the A metering in K-mount. Your lens can be used in both Pentax KA mount in 'A' setting. And it beats the others with an addition of 'P' ricoh pin that allows you to use the special Ricoh programmed (or multi-programmed) mode in Ricoh xr, xr-p and any other Ricoh cameras with P settings.

The Ricoh pin shown below is retractable. The reason why it get stuck half-way before is the pin likely got onto the AF/MF switch on body. Once it get stuck and you can't slide it further, try gentle wiggle as you have done. The last resort is to switch AF/MF switch on body to push the pin out and slide the lens further to lock in position







You can send your Ricoh P lens my ways if they are too much troubles for you I will hopefully find time to document the notorious Ricoh P pin and how it is used in Ricoh Programmed film cameras and how to avoid the pin getting stuck scenario.

An ricoh R-K lens without the Pentax A, P setting is for Ricoh Programmed mode, the equivalent of Pentax A but the P can't be used as 'A' on Pentax K body, those Rioch only K-R lens can only be used stopped down in K-bodies






Your Sigma lens is different as it is likely to have P/K-AR that work with both Pentax bodies with A setting and Ricoh body that supports P for programmed/multi-programmed modes.

Thanks,
Hin
12-15-2009, 01:02 PM   #12
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Photo of my later version of the Sigma 24/2.8. The Ricoh pin is at the top center:

12-15-2009, 03:20 PM   #13
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Hin just wants your lens for his newly-acquired Ricoh XR-P

Steve
12-16-2009, 06:41 AM   #14
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thanks guys. Yeap, the problem exactly was that : the retractable ricoh pin got into the af/mf hole and stopped the lens from moving further into locking into position. Gently wiggling it once locked released it and allowed it to move further. Or in my case, forcefully wiggling it for 2 hours. hahah. It is now moving into position with no problem.
12-16-2009, 11:48 AM   #15
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QuoteOriginally posted by D4rknezz Quote

thanks guys. Yeap, the problem exactly was that : the retractable ricoh pin got into the af/mf hole and stopped the lens from moving further into locking into position. Gently wiggling it once locked released it and allowed it to move further. Or in my case, forcefully wiggling it for 2 hours. hahah. It is now moving into position with no problem.
Thanks for the report. You should look around for document on how to remove the pin if that really bothers you. I recommend highly my good friend Robin's article on his attempt on Ricoh Pin Fix but I will caution about the risk involved and that the risk is justified on how frequent and how jammed the Ricoh pin has given you grief.

As for my use, I will keep the pin intact as long as it is found to be retractable and there is work-around with gentle wiggling and slide by the AF/MF switch with no issue. I blogged about the Ricoh pin and Ricoh R/K mount in my latest blog post.

For those lens with R/K mount without the 'A' setting but rather a 'P' setting for Ricoh programmed mode, you see the rear mount as follows


Access R/K mount on left
Cosina 55mm f/1.2 PK-mount on right
Ricoh pin pointed by red blower tip on bottom left


Thanks,
Hin
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