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07-21-2017, 12:12 PM   #1
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Metering Issue using M42 adapter?

Hello! Newb, here :-)

I got a K&F Concept M42-K adapter (its one that does NOT have a tool), to mount my Super Takumar 50/1.4 on a K1000. This seemed a real 30 sec piece of cake. But there's odd things going on with metering; I took it out into the painfully sunny day and the meter pinged right to the top (+) on f16... I open it up to 5.6 for a decent reading, but the viewing is darkened enough to annoy focusing, and the prism is darkened. Do I ignore the metering sytem and shoot by instinct? I'm newish to film and manual shooting, so please advise! Thanks! (the lens is switched to 'manual' from auto).

07-21-2017, 12:32 PM   #2
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QuoteOriginally posted by vwpunx Quote
Hello! Newb, here :-)

I got a K&F Concept M42-K adapter (its one that does NOT have a tool), to mount my Super Takumar 50/1.4 on a K1000. This seemed a real 30 sec piece of cake. But there's odd things going on with metering; I took it out into the painfully sunny day and the meter pinged right to the top (+) on f16... I open it up to 5.6 for a decent reading, but the viewing is darkened enough to annoy focusing, and the prism is darkened. Do I ignore the metering sytem and shoot by instinct? I'm newish to film and manual shooting, so please advise! Thanks! (the lens is switched to 'manual' from auto).
An easy alternative to put the Takumar on auto, compose, then switch to manual, and set the aperture according to the light meter. Or, just compose wide open, and then stop down until the meter is happy.
07-21-2017, 01:28 PM   #3
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QuoteOriginally posted by marcusBMG Quote
Check that the iris is opening and closing correctly as you move the aperture ring and/or the A-M switch with the lens off the camera. You should be in Av mode ie stop down metering. Focus wide open, then use the A-M switch or the aperture ring to stop down at the moment of taking the picture.
Note that the black non conducting mount causes some issues on some pentax dslr models like my old K-r see the piece I wrote here:

TESTS: Plated vs Painted (conducting vs non-conducting) lens mounts on K-r: whats t - PentaxForums.com
I'm pretty sure the K1000 has one mode - manual.
07-21-2017, 02:02 PM   #4
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The K1000 is "always on" metering. If the meter pegs check your battery.

Key parameters you fail to share is film speed and shutter speed. If you are at f16 and ISO 400 film it is possible to peg if your shutter speed is 1/125 or slower. (Sunny sixteen would say you need 1/500 for f16 and ISO 400, pointed at the sky if it's bright you might need f22).

07-21-2017, 02:23 PM   #5
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Battery is good. Yep, one mode- manual for K1000's....

ISO 100, had it on 1/250.
07-21-2017, 03:16 PM   #6
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Not particularly helpful, but when I use my 50mm Tak on my MX or LX, I've always found it easier to use a handheld meter to get a reading, focus, then stop down and shoot. Using the internal meter when you have to stop the lens down always just felt like a fiddle pain in the bum...
07-21-2017, 04:09 PM   #7
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I read the previous responses and I am a bit confused now too. Do you have a copy of the K1000 manual? You can download for free from HERE. It has a section on how to use adapted M42 lenses. As for my attempt to add to the confusion...Here is the flow:
  1. Place the Auto/Manual switch (A/M switch on some cameras) in the Manual position and adjust the shutter speed and/aperture ring to center the meter needle. Yes, the viewfinder will darken when moving to a narrower aperture. If your lens lacks such a switch and is wide open regardless of aperture ring position, it cannot be used on your K1000 without modification. Edit: Alternatively, determine exposure using a reading from a hand-held meter and set those on the camera.
  2. Switch the lens back to the Auto position and focus on the subject.
  3. Switch lens to the Manual position and take the photo.
  4. Repeat steps #2 and #3 until either the light or the subject changes
This flow seems cumbersome, but is the norm with lenses lacking automatic aperture actuation or when using a body that does not couple with the actuator on the lens (e.g. All K-mount cameras with M42 lenses). The nice part is that the A/M switch allows for stop-down action that is both fast and accurate to the intended aperture.

FWIW, this system was well-received by owners of M42 lenses as a reasonable accommodation in 1975 when the K-mount debuted. After all, most were already well-acquainted with stop-down metering and many may have owned lenses with pre-set or fully manual apertures. (The pre-set lens flow on a Spotmatic is almost identical to what I outlined above.)


Steve

Last edited by stevebrot; 07-21-2017 at 04:23 PM.
07-21-2017, 04:19 PM   #8
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QuoteOriginally posted by stevebrot Quote
This flow seems cumbersome
The flow is cumbersome

That is why shooting adapted M42 lenses is fairly rare for film photography given that good M42 bodies are fairly easy to to come by. On those cameras, the picture taking process can be quite fast and intuitive. Meter once and shoot lots with no need to adjust anything but focus.


Steve

07-21-2017, 09:48 PM   #9
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You'll have to get an M42 body in order to not have the screen go dark when you stop down, unfortunately. If you wanted to avoid that, you could use the lens only on apertures between/including 1.4 and 3.5 so the microprism doesn't go dark, just keeping the lens on 'manual' and metering normally...and use other lenses in daylight.


Putting the lens on auto will keep the aperture wide open for focusing and viewing until you fire the shutter, and then it closes the aperture down to the aperture set on the lens - if there is a mechanism in the camera to push the little pin on the lens. But the K1000 doesn't have that mechanism for M42 lenses, only M42 cameras do. So, with an M42 lens adapted onto a K mount camera, you will have to close the lens down to shooting aperture yourself ('manual'), and it gets darker in the viewfinder when you do. Just to clarify, f1.4 is wide open, and f16 is stopped down.

Last edited by Ranchu; 07-22-2017 at 06:30 PM.
07-21-2017, 11:28 PM   #10
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K&F sells two styles of M42 adapters - one looks like a knock-off of the OEM Pentax adapter while the other is flanged (no infinity focus) adapter.

The OEM adapter when installed properly sets the aperture linkage lever to a position that enables stop-down metering. While the K&F adapters appear to have cutouts for the aperture linkage. I could not say by the photos if the cutout is in proper position for stop-down metering.
07-22-2017, 04:39 AM   #11
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QuoteOriginally posted by Not a Number Quote
K&F sells two styles of M42 adapters - one looks like a knock-off of the OEM Pentax adapter while the other is flanged (no infinity focus) adapter.

The OEM adapter when installed properly sets the aperture linkage lever to a position that enables stop-down metering. While the K&F adapters appear to have cutouts for the aperture linkage. I could not say by the photos if the cutout is in proper position for stop-down metering.
I've used a few different knock-off M42 adapters, and have yet to have an issue with stop-down metering.
07-22-2017, 01:11 PM   #12
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QuoteOriginally posted by stevebrot Quote
The flow is cumbersome

That is why shooting adapted M42 lenses is fairly rare for film photography given that good M42 bodies are fairly easy to to come by. On those cameras, the picture taking process can be quite fast and intuitive. Meter once and shoot lots with no need to adjust anything but focus.


Steve
I use SP, SV or S1a all cheap finds in junk shops and market stalls.
07-22-2017, 02:16 PM   #13
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QuoteOriginally posted by Not a Number Quote
The OEM adapter when installed properly sets the aperture linkage lever to a position that enables stop-down metering. While the K&F adapters appear to have cutouts for the aperture linkage. I could not say by the photos if the cutout is in proper position for stop-down metering.
Good observation and comment

Too expand a little...A proper adapter (flanged or otherwise) has a cutout to engage the aperture position coupler on a "non-crippled" K-mount. When the adapter is fully engaged, the coupler will be at the position for maximum aperture (required for stop-down metering). The position of the cutout slot has historically been a potential issue with brand-X adapters when used with bodies having non-crippled mounts (K, KM, KA, KAF, KAF2).*

QuoteOriginally posted by timw4mail Quote
I've used a few different knock-off M42 adapters, and have yet to have an issue with stop-down metering.
It is not issue with "crippled" K-mount bodies (all Pentax dSLRs) or with adapters for other than K-mount. Even then, most reputable dealers are aware of the problem and bad slot placement is something I have not read of in a long time.


Steve

* Bad slot position has symptoms similar to poorly machined adapters with improperly shaped bayonet tabs that allow the adapter to over-rotate in the mount; that being inappropriate bias applied to the meter output.

Last edited by stevebrot; 07-22-2017 at 02:35 PM.
07-22-2017, 04:14 PM   #14
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They're talking about the little tab on the inside rim of the K mount, it senses what aperture you set the lens on when you have a K mount lens on the camera, so the meter knows. When you have an adapter on, the slot in the adapter puts the tab in a 'neutral' position, so the meter isn't affected by the tabs position and just reads the light falling on the focus screen. Apparently sometimes it can be machined in the wrong place. Good to know.

Last edited by Ranchu; 07-22-2017 at 04:19 PM.
07-22-2017, 05:29 PM   #15
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I have removed my comment.

Steve

Last edited by stevebrot; 07-22-2017 at 06:11 PM.
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