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11-16-2014, 08:08 PM   #1
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Ricoh "P" for Pentax

The contact on a Ricoh "P" lens for AV use is in the wrong spot for a Pentax. Has anyone ever moved the contact to the correct place so it will work in AV for Pentax? IS THERE A FIX FOR THE PROBLEM?

11-16-2014, 08:13 PM   #2
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QuoteOriginally posted by Rimfiredude Quote
The contact on a Ricoh "P" lens for AV use is in the wrong spot for a Pentax. Has anyone ever moved the contact to the correct place so it will work in AV for Pentax? IS THERE A FIX FOR THE PROBLEM?
The P isn't for "Av" use -- it is for a special Ricoh mode that existed on film cameras, there is no A pin or A contacts on these lenses. So no, you can't use Rikenon P lenses as A lenses, only as fully manual M-type lenses. It isn't a "problem", is it just something to be aware of...
11-16-2014, 08:17 PM   #3
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QuoteOriginally posted by vonBaloney Quote
The P isn't for "Av" use -- it is for a special Ricoh mode that existed on film cameras, there is no A pin or A contacts on these lenses. So no, you can't use Rikenon P lenses as A lenses, only as fully manual M-type lenses. It isn't a "problem", is it just something to be aware of...
Too bad. I just received the non P version today. It is absolutely fantastic. Very easy to focus compared to my f2 50 Pentax and sharper also. I was hoping it could be done...wishful thinking.
11-16-2014, 08:44 PM   #4
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I've always wondered if you could self modify lenses into an "A" lens to give back aperture data.

Not even change it for you, just give back certain data and maybe even properly expose it.

11-16-2014, 09:33 PM   #5
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There are ways to trick the camera into thinking a non-A lens is an A lens (which involves a camera modification also from what I remember), but the aperture positions do not sync up properly, i.e. if the body sets the aperture to f/5.6 it won't really be 5.6 on the lens. I just don't think it is worth all the trouble because it will never be like a real A lens. You could remove the aperture lever entirely, which prevents the body from opening up the aperture when mounted -- it will be in whatever the position the ring is set to at all times as so is like using an adapted m42. This way you stop down manually with the ring, but you can use Av mode and the camera adjusts as you open and close the aperture. (The metering is sometimes a bit off as you stop down.) Or you just leave it as it is and use M mode with green-button metering.
11-16-2014, 11:15 PM   #6
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QuoteOriginally posted by ZombieArmy Quote
I've always wondered if you could self modify lenses into an "A" lens to give back aperture data.

Not even change it for you, just give back certain data and maybe even properly expose it.
It's been attempted quite a few times, and generally, no. Even if you create the "A" contacts to tell the body the smallest and largest f-stops of the lens, if the action of the linkages isn't linear (it wasn't on K- or M- lenses), then the body won't expose correctly for the whole range. You would have to replace the mechanics of the lens as well.

QuoteOriginally posted by vonBaloney Quote
You could remove the aperture lever entirely, which prevents the body from opening up the aperture when mounted -- it will be in whatever the position the ring is set to at all times as so is like using an adapted m42.
An easier way is to put some cellophane tape on the lens mount, so that it is insulated from the contacts on the body. The body does not detect a K-mount lens and treats it like an M42.
11-17-2014, 03:04 AM   #7
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QuoteOriginally posted by THoog Quote
An easier way is to put some cellophane tape on the lens mount, so that it is insulated from the contacts on the body. The body does not detect a K-mount lens and treats it like an M42.
Doesn't it still hold the aperture open mechanically though? If the lens is mounted, the aperture is held wide open by default (even if the camera is off, so you can still look through the viewfinder, the K-01 being an exception which does not open it until turned on). Are you saying if I remove conductivity it is going to automatically release the aperture (which will allow it to open and close by turning the ring while mounted) when I turn on the camera?
11-17-2014, 03:12 AM   #8
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QuoteOriginally posted by vonBaloney Quote
Are you saying if I remove conductivity it is going to automatically release the aperture (which will allow it to open and close by turning the ring while mounted) when I turn on the camera?
It couldn't be too hard to test

11-17-2014, 03:42 AM   #9
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The neutral position of the stop down lever holds the iris wide open. It doesn't matter if the camera is open or not. M42 use an entirely different system so there is no linkage. All you have to do to test this is set your K-mount lens to the smallest aperture, leave the lens cap off and mount the lens. As you twist it into the locked position the iris will stop down.

On some DSLR models if you insulate the pins the green button won't work and the lens won't stop down. This is a problem with 3rd party lenses, T-mount adapters, and extension tubes that have non-conductive mounts.

The pins on Rikonon lenses are not compatible with Pentax.
11-17-2014, 07:26 AM   #10
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QuoteOriginally posted by vonBaloney Quote
Doesn't it still hold the aperture open mechanically though? If the lens is mounted, the aperture is held wide open by default (even if the camera is off, so you can still look through the viewfinder, the K-01 being an exception which does not open it until turned on). Are you saying if I remove conductivity it is going to automatically release the aperture (which will allow it to open and close by turning the ring while mounted) when I turn on the camera?
Hmm. I guess it only works on the K-01. My mistake.
11-18-2014, 04:42 PM   #11
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QuoteOriginally posted by Rimfiredude Quote
Ricoh "P" for Pentax
I was going to say you might need to post this in a more appropriate section on the forum to get more replies, well that's not the case here.
11-18-2014, 07:01 PM   #12
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QuoteOriginally posted by Kerrowdown Quote
I was going to say you might need to post this in a more appropriate section on the forum to get more replies, well that's not the case here.
I think my questions have been answered. IT CAN'T BE DONE.
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