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07-18-2013, 08:26 PM   #1
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Helios 44M possibly shorting body contacts?

I inherited my uncle's Zenit camera and its Helios 44M M42 lens. The back of the lens body seems to touch and possibly short the K-mount contacts on my K-30. I am using a genuine Pentax adapter. Does this situation cause any harm to the normal operation of the camera?

07-18-2013, 08:58 PM   #2
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it would be impossible to mount an M42 and have it tightly screwed without something touching the contacts. in the case of the authentic adapter it is the actual lens body. in the case of the ebay knockoffs its usually the adapter (but you dont have infinity focus). all of my M42 do that (i have various takumars and a helios 44-3). I wouldnt worry about it
07-19-2013, 08:56 AM   #3
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Lenses that don't short the body contacts can confuse the camera, according to some threads on the forum. People use foil or grind off the paint when the lens is not pure metal where the contacts are.
07-19-2013, 09:13 AM   #4
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My M42 Takumars have a very small footprint and do not short the contacts. This 44M covers the contacts. Sometimes my K-30 switches out of Liveview or "double shutters" while only recording one image.

Should I dissolve the black paint on the back of this lens? Should fully manual lenses either completely short/open the contacts or can they be intermittent due to the paint providing a weak insulation?

07-19-2013, 03:33 PM   #5
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Here's a link that suggests that painted mounts can cause problems with metering and catch-in-focus.

https://www.pentaxforums.com/forums/general-technical-troubleshooting/230750-...g-problem.html
07-19-2013, 09:55 PM   #6
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QuoteOriginally posted by 6BQ5 Quote
The back of the lens body seems to touch
The back of your lens is supposed to snug up against the body flange and most M42 lenses have a wide enough base to cover all of the contacts and most of the mount flange. Many FSU M42 lenses as well many German M42 (and early Super-Taks) are fairly narrow at the rear and often don't adequately engage the body flange when adapted to K-mount and "rock" as a result, but that is another matter. Your Helios 44M is not one of them. Back to your question...Whether it touches the contacts should not make any difference as long as the "A" (recessed) contact is not shorted. That is how the camera "knows" whether an A series or newer lens is mounted. For example, all Pentax-K and Pentax-M lenses have conductive bases that short all of the contacts except the recessed "A" contact. A-contact lenses with the aperture ring on the "A" setting have a pin that protrudes and completes the circuit. Move the aperture off the "A" setting and the circuit is broken. Notice that I said "should" a few sentences back. For some reason, my adapted LZOS MC Jupiter-9 85/2 will sometimes register with my K10D as having A-contacts. I have put an ohmmeter to the base and sure enough the paint is mildly conductive. Why this never happens with my other lenses is a mystery to me, but it can be problematic when shooting in Av mode.


Steve

Last edited by stevebrot; 07-19-2013 at 11:03 PM.
07-19-2013, 10:30 PM   #7
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QuoteOriginally posted by Canada_Rockies Quote
Here's a link that suggests that painted mounts can cause problems with metering and catch-in-focus.

https://www.pentaxforums.com/forums/general-technical-troubleshooting/230750-...g-problem.html
There is a lot of confusion on this matter and the behavior appears to differ according to the model of camera and maybe even according to firmware version. I am able to use catch-in focus with all of my lenses with conductive bases on the K10D (firmware v1.20). Those include the above-mentioned Jupiter-9 and is true for that lens even when the camera "thinks" (correctly) that it has no A-contacts. I don't know that this is true for other bodies, though I have read reports of users sanding the paint off their M42 lenses for the purpose of enabling catch-in focus with good success.

As noted above and in my previous comment, the base of my Jupiter-9 is conductive enough to allow catch-in focus and on rare occasions even results in the camera displaying an aperture in the display. This makes no sense in that the A-contact is supposed to "gate" aperture control by the body and does so effectively on my other A-contact body (Super Program film camera). I believe it is due to a bug (ahem...feature) in the firmware.

To muddy the waters, there is a persistent rumor that fully shorting the contacts with foil (pressing the foil into the indent for the "A" contact) will magically correct metering issues on the older K10D and K20D bodies by making the camera think that an A-contact lens is mounted. I remember doing this experiment a few years back and sure enough the "F---" disappeared and an aperture number was displayed instead. What this meant is that I could do green button metering in M mode with the lens wide open and set the lens manually to the aperture on the display and get better accuracy. I cut the experiments short because I was wary of possibly doing an "illegal" combination of contacts and damaging something. (I know...sounds superstitious, but I write software and superstition is a valuable attribute in my profession.) Besides that, the trick only worked with my M42 lenses.

Short summary? I would discourage fiddling with the contacts beyond possibly sanding the bases on non-conductive lenses to enable catch-in focus, assuming that is important to you.


Steve


P.S. I have one of the early Super-Tak 55/1.8 with the thin mount flange. If mates up perfectly to the body flange on my SV film body and barely has enough width to snug up to the body when adapted to k-mount and quite nicely does not touch any of the contacts. It meters the same on the K10D as my later version with the wider flange which means that it meters the same as my Pentax-K 55/1.8...lousy.

Last edited by stevebrot; 07-19-2013 at 11:02 PM.
07-19-2013, 10:56 PM   #8
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QuoteOriginally posted by 6BQ5 Quote
Sometimes my K-30 switches out of Liveview or "double shutters" while only recording one image.
I believe this is another known issue that is not related to your lens. You may want to contact Pentax support if the camera is still on warranty.


Steve

07-20-2013, 07:40 AM   #9
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Steve,

Thanks for yur multiple replies here! I installed my Pentax M42 adapter mount into my K-30 and started lining up the Helios 44M lens to the body. It seems that the screw mount threads are fairly deep and that there is an extra bit of unthreaded metal beyond the threads. All of this together makes me think that the the threaded and unthreaded areas of the mount go pretty deep. I compared this to my 28mm f/3.5 Tak and the difference in mount protrusion into the body is significant. Could the lens mount be touching the internal recessed contacts? I think the possibility is high.

I'm traveling right now so posting a good quality photo is difficult.
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