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05-07-2008, 06:29 AM   #1
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M42 on K10D question

I jut got my first M42 lens. I had a question concerning mounting on the camera. I am using the Pentax adapter and it seems to fit loose on the body. Is it supposed to wiggle radially? After screwing the lens to the adapter it makes the lens move.

I guess here is another question: What actuates the auto pin? I don't see a lever or something in the body that would stop down the lens when the switch is set to auto.

Scott

PS - I'll post the obligatory LBA post after I get back from a trip this weekend. I am hoping to try it out, and the 24-135 there.

05-07-2008, 07:51 AM   #2
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I have a copy of the Pentax adapter and it also wiggles a bit. Un-nerving, but it seems to work. As for the auto pin, there isn't any actuation the M42 lens (or any lens on an adapter that I've seen). You have to set the aperture for metering and taking the shot manually.
05-07-2008, 08:24 AM   #3
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Let me suggest a reason for the 'wiggles'. Some M42 non Pentax lenses have a step on the flange that would contact the camera body when the lens is screwed in. If the diameter of this step is equal to or less than the adapter diameter, the lens will move because it will not contact the camera body only the adapter. The few Pentax M42 lenses I have do not have a step in the flange. On a film camera this lens design with the stepped flange would work fine.

Regards

Jan
05-07-2008, 08:35 AM   #4
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My four M42 Pentax lenses all fit tightly on my k10d with the adapter.

05-07-2008, 09:00 AM   #5
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Hi Scott. Does your adapter have the little spring? When I install my adapter, the spring provides a solid 'click' and seats the adapter. I wonder if yours is missing or weak?
05-07-2008, 10:25 AM   #6
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I actually took the little spring thing out of mine. I found it was a pain to use and the adapter stays in tight just through friction.
05-07-2008, 10:47 AM   #7
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QuoteOriginally posted by YarPcola Quote
I actually took the little spring thing out of mine. I found it was a pain to use and the adapter stays in tight just through friction.
I like that idea, except I only have the one adapter and when changing lenses I'd rather the adapter stay put
05-07-2008, 10:57 AM   #8
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QuoteOriginally posted by YarPcola Quote
I actually took the little spring thing out of mine. I found it was a pain to use and the adapter stays in tight just through friction.
Mine doesn't have enough friction for that.

Scott, you have to set the lens to "Manual" as there is nothing to actuate the pin.

05-07-2008, 11:49 AM   #9
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rormeister: I assume by the little spring you mean the black spring steel tab that locks the ring in position - if so, yes that is there and it does click in position. However, it is not securely held, and has a bit of rotation to it. I assume the Pentax logo should be at the 12:00 position or am I not turning it far enouogh.

gussegutt: I will look for the flange when I get home (at work now). if there is something contacting the ring prior to hitting the camera body, should I eliminate it? I imagine that this would affect the lenses distances somewhat. I am sure I can seal things and get out the dremel...

thanks for all the info...

Scott
05-07-2008, 01:41 PM   #10
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I have the official Pentax adapter and mine wiggles some on my K10D and even more on my Ricoh XR-7. Very unnerving.
05-07-2008, 01:57 PM   #11
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Mine doesnt move a bit. And its the Pentax one.
05-07-2008, 02:26 PM   #12
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Scott, congratulations on joining the M42 club.

I'm using a genuine Pentax adapter with the locking spring removed, and I'm not detecting any wiggle. As far as use goes, set the switch on the lens to manual, and you can use 'M' mode on the camera metering via the Green button, or you can use 'Av' mode. I've just started playing with my first M42 and find focusing on sunny days possible at f/8 or so.
05-07-2008, 08:54 PM   #13
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I wrote up a blog post talking about the Genuine Pentax adapter


As far as I remember, I don't recall any wiggling that I have observed from both the genuine and 3rd party adapters
05-07-2008, 10:09 PM   #14
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It is not much of a wiggle. Actually the lens is quite snug onto the body. What it does do is to shift about 1-2 degrees of arc on the K10D when I twist the focus on the all-to-stiff Jupiter-9 (not too bad), but on my Ricoh 35mm SLR the shift is about 2-3 degrees (feels pretty rickety).

Steve
05-08-2008, 06:18 AM   #15
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Gussegut:
Is this the step you are referring to? Yes, I took the lens apart. I am quite technical in nature. I can get a 0.006 to 0.007" shim in between the lens and the body when it is mounted. It looks like I can't see light between the lens and the body, however there is obviously a gap. I tried one of my Sigmas and it is tight to the body. It must be contacting the adapter, and not letting it screw in farther, as the aperture lines do not come all the way to the top. Not sure if this is a big deal or not. Anyway, I will probably screw this back together and get a few shots, see if infinity is affected. If needed, I can remove the cap, take apart the A/M mechanism inside and see if I can get that machined down.

Stevebrot:
Yeah, that is about what I have too, probably a little more, like 3-4 deg. All seems tight and it does not feel like the lens will fall off or anything, Just not what I expected.
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