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08-23-2016, 09:58 AM   #1
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Stop down metering M42 lenses on K-30?

I recently picked up a Helios 44-2 58mm ƒ/2 lens and absolutely love shooting with it on my old Pentax MX. I wanted to try it on my K-30 today and encountered an issue. My camera is already set up for stop down metering, since I occasionnally use some M series glass on it and it usually works like a charm. But using the Helios and an adapter (the correct no-flange one), pressing the green button in manual mode does absolutely nothing. I know this lens doesn't have an aperture lever unlike the M series lenses, but neither do the M42 Takumars and they're supposed to work fine (never tried though, since I don't own any Takumars). Has anyone come across this issue with M42 lenses?

08-23-2016, 10:20 AM - 1 Like   #2
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Check out these and many other threads:

https://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/316239-t...resistant.html

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

https://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/327660-c...-does-not.html

I use Av mode usually with M42 ie stop down metering. stop the lens down just before firing the shutter.

Last edited by marcusBMG; 08-23-2016 at 10:59 AM.
08-23-2016, 10:44 AM   #3
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To get a proper exposure with the m42 mount lenses..

Set your green button properly: go to E-dial programming and change 'M' to TvShift.
Now when taking a picture in M mode, focus with a wide open aperture, stop down to the aperture you want to use using the aperture ring on the lens, press the green button to acquire a light meter reading which sets your shutter speed, take your picture.

Next option is to simply use Av mode, instead. Your shutter speed will be set automatically when you stop down the lens.

If your m42 lens doesn't stay at the chosen aperture when moving the aperture ring (only stops down when you press the pin) then you need to modify the lens by either super gluing down the pin or pushing it so far in it won't come back out. Both ways are destructive so be sure you want to go this route. I've also heard of people disassembling their lens and puting some sort of bushing around the pin so that it won't break the lens.
08-23-2016, 11:01 AM   #4
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QuoteOriginally posted by FozzFoster Quote
If your m42 lens doesn't stay at the chosen aperture when moving the aperture ring (only stops down when you press the pin) then you need to modify the lens by either super gluing down the pin or pushing it so far in it won't come back out.
Generally this is only required with M42 lenses that don't have an auto/manual (A/M) clutch located near the aperture ring. Unfortunately I think this includes the aforementioned Helios types (or some of them at least).

The A/M clutch was a thoughtful little device designed to ensure backwards compatibility for cameras that didn't have a flapper plate to link stop-down to shutter actuation, or when the user wanted to mount them on bellows, or extension tubes without feed-through connectors for the pin. These days, of course, it ensures forwards compatibility with essentially all DSLRs (if there is an M42 mount DSLR with a flapper plate actuator out there, I haven't heard of it but I reckon fans of the old glass would be all over it, as this old thread proves).

08-23-2016, 12:35 PM   #5
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m42 lenses only have manual stop down metering. Put the camera in AV , focus, then stop down manually and take the shot. At wide apertures expect some under exposure. I usually shoot at +0.7 or +1ev. When the lens has a a/m switch you can also use that to stop down. (set it to A stop down (vf remains bright) push it to M and it stops down. Camera will meter automatically.
08-23-2016, 02:19 PM   #6
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Well that explains it. I have an early version Helios 44-2, without the stop-down pin. The diaphragm is stopped down manually via a ring at the front of the lens. Now the mount of that lens is so narrow that is misses the contacts by a mile. The green button works as soon as I short the contacts with a piece of metal, so I guess all I have to do is to stick a small piece of aluminum foil there to make it work.
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08-23-2016, 03:15 PM   #7
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QuoteOriginally posted by ticoun Quote
early version Helios 44-2
Aye, and see this thread too.

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/302385-prev...-solution.html

These lenses do better mounting wise with a flanged adapter* - fixes wobbles, contacts, lens lock, light leaks... loses far focus of course but maybe thats ok for many of the pics you're taking. Certainly I make a point of having one handy.
*Silver one like ebay item 400957305893 from lakeyx101

Last edited by marcusBMG; 08-23-2016 at 03:31 PM.
08-23-2016, 03:22 PM   #8
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With a m42 lens the green button doesn't do anything but reset your settings (in P/Av/TAv) and is ineffective in M. The 44-2 has 2 aperture rings. The pre-set ring with which you pre-set the aperture you want to use without actually closing it (the front one which clicks) and the second one which doesn't click stops down to the pre-set aperture. So you pre-set the desired aperture with the front ring and focus and then close it with the second stepless ring. The camera will never close the aperture as it is not from the 1960's or 70's and says Zenit.

08-23-2016, 08:23 PM   #9
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QuoteOriginally posted by marcusBMG Quote
Aye, and see this thread too.

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/302385-prev...-solution.html

These lenses do better mounting wise with a flanged adapter* - fixes wobbles, contacts, lens lock, light leaks... loses far focus of course but maybe thats ok for many of the pics you're taking. Certainly I make a point of having one handy.
*Silver one like ebay item 400957305893 from lakeyx101
After some testing in various lighting conditions, yep, there are light leaks coming from those holes. I guess I'll be heading to the hardware store plumbing department tomorrow.
08-24-2016, 12:52 AM   #10
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you can also use an elastic hair band
08-24-2016, 11:22 AM   #11
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QuoteOriginally posted by marcusBMG Quote
Aye, and see this thread too.
https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/302385-prev...-solution.html
These lenses do better mounting wise with a flanged adapter* - fixes wobbles, contacts, lens lock, light leaks... loses far focus of course but maybe thats ok for many of the pics you're taking. Certainly I make a point of having one handy.
QuoteOriginally posted by ticoun Quote
After some testing in various lighting conditions, yep, there are light leaks coming from those holes. I guess I'll be heading to the hardware store plumbing department tomorrow.
This is all very interesting. Last Spring I bought a generic ring and a Mir 37mm lens as part of my "be prepared for Aperture Block issues" on K-30 kit. On a Memorial Day weekend trip to Greenfield Village in suburban Detroit, I disciplined myself to use the Mir lens only {outside, on a hot, sunny day} just to see what that would be like {and convinced myself I can do it, although I missed zoom and AF}. I hadn't heard any of this stuff then. Somehow none of my images shows any sign of light leakage.

added thought: going back to the original subject of this thread. All day I had the camera in Av mode and kept the lens stopped down. Perhaps my natural tendency to use smaller apertures, around f/5.6 or f/8, gave me enough leeway in DOF, but focusing was easy at those f-stops and metering was the same as a KA-mount lens at the same Av setting.

Last edited by reh321; 08-24-2016 at 11:27 AM. Reason: added thought
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