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11-28-2011, 07:01 PM   #1
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I got multi-segment metering on an M42 lens--how?!

I was shooting some test shots with an M42 lens of mine and glanced at the screen to find out it had multi-segment metering active! I have no idea what I exactly did. I unmounted and remounted the lens to see if it would still have multi-segment as a metering option. Nope. I never been able to replicate it.

Has anyone experienced this and/or know how to go about doing this?

I looked everywhere on how to get multisegment metering on M42 lenses and read it wasn't possible.

The only things I do know:
1) I have metal tape on the base of the M42 lens for Catch-In-Focus and improved metering.
2) I previously had my A50/1.7 with multi-segment metering active before mounting the M42.
3) The camera was off when I changed lenses...I think.

Whether those had anything to do with it, I have no idea.

Even though this multisegment metering might not even be accurate (assuming it's available only on A-lenses and newer because the camera needs to communicate with the lens) or even useful, I'd still like to know if anyone has experienced this before.

11-28-2011, 07:10 PM   #2
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Metering segments have nothing to do with the lens. You can choose the metering type using the switch directly under the mode selection dial.

Adam
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11-28-2011, 07:19 PM   #3
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QuoteOriginally posted by Adam Quote
Metering segments have nothing to do with the lens. You can choose the metering type using the switch directly under the mode selection dial.
On the K-x (maybe just my K-x?), I can only choose between spot and center-weighted metering when using M42 or Pentax-M lenses.

Along with what you said, that's what I've always thought; the metering is done by the camera and not the lens. This always made me wonder why multi-segment metering was disabled on M42 and M-series lenses (on just the K-x? just my K-x?).
11-28-2011, 07:22 PM   #4
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QuoteOriginally posted by MobiusOne Quote
On the K-x (maybe just my K-x?), I can only choose between spot and center-weighted metering when using M42 or Pentax-M lenses.

Along with what you said, that's what I've always thought; the metering is done by the camera and not the lens. This always made me wonder why multi-segment metering was disabled on M42 and M-series lenses (on just the K-x? just my K-x?).
No, the K5 is also limited to center-weighted with M42, K and M lenses. Page 337 of the manual. The chart is basically the same as in the K-x manual but includes TAv mode.

11-28-2011, 08:14 PM   #5
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Same with the K-r. Spot and center only with manual lenses. Adam, what model(s) are you referring to? OP didn't specify which he has.
11-28-2011, 09:32 PM   #6
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My LZOS MC Jupiter-9 85/2 periodically identifies as an A-series lens on my K10D. The paint on the base is mildly conductive. It is actually sort of a pain since the camera thinks that is controlling the aperture when shooting in Av mode even though there is no coupling and the "feature" can turn on at anytime during the session!


Steve

Last edited by stevebrot; 11-28-2011 at 09:42 PM.
11-28-2011, 09:49 PM   #7
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QuoteOriginally posted by stevebrot Quote
My LZOS MC Jupiter-9 85/2 periodically identifies as an A-series lens on my K10D. The paint on the base is mildly conductive. It is actually sort of a pain since the camera thinks that is controlling the aperture when shooting in Av mode even though there is no coupling and the "feature" can turn on at anytime during the session!


Steve
Any lens pain should be considered serious.
I'd get that checked asap.
11-28-2011, 10:06 PM   #8
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Man never walked on the moon, the earth is actually flat . . . an' multi-segment metering is just a figment of marketing hype.

By the way, what does the EXIF data record for that event? Is it possible you mistook the CW icon for MS metering . . . as I often do?

H2

11-28-2011, 10:15 PM   #9
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QuoteOriginally posted by Adam Quote
Metering segments have nothing to do with the lens. You can choose the metering type using the switch directly under the mode selection dial.
Not quite right. Unsupported lenses default to center-weighted if you have the switch set to multi-segment.
11-28-2011, 11:33 PM   #10
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QuoteOriginally posted by MobiusOne Quote
1) I have metal tape on the base of the M42 lens
My M 50 doesn't let me do multi-segment metering, even if I try intentionally mis-aligning some contact points hoping that would work... Maybe the camera got tricked by the metal tape?
11-29-2011, 12:27 AM   #11
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QuoteOriginally posted by Alizarine Quote
My M 50 doesn't let me do multi-segment metering, even if I try intentionally mis-aligning some contact points hoping that would work... Maybe the camera got tricked by the metal tape?
Dozens of my manual lenses have metal tape on their bases and none of them instigate matrix metering. A trick has been mentioned elsewhere that involves shorting one of the body-mount contacts from the inside. Maybe a bit of metal tape got shoved down into the contact-pin sleeve?
11-29-2011, 12:38 AM   #12
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QuoteOriginally posted by Alizarine Quote
My M 50 doesn't let me do multi-segment metering, even if I try intentionally mis-aligning some contact points hoping that would work... Maybe the camera got tricked by the metal tape?
You have an M with contact points?
11-29-2011, 12:47 AM   #13
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QuoteOriginally posted by Mike Cash Quote
You have an M with contact points?
None, of course. One- well not a contact point, more of a notch, a depression in the lens, near the aperture lever. I was thinking before if those points on the body if aligned to that notch might get it to work..
11-29-2011, 05:20 AM   #14
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QuoteOriginally posted by pacerr Quote
By the way, what does the EXIF data record for that event? Is it possible you mistook the CW icon for MS metering
It was definitely MS metering. It was recorded as an A lens with an aperture of 1.4 (which I wish either lens were capable of)! Screenshot of exif info attached.

QuoteOriginally posted by RioRico Quote
A trick has been mentioned elsewhere that involves shorting one of the body-mount contacts from the inside. Maybe a bit of metal tape got shoved down into the contact-pin sleeve?
Ah, this might be it. The edges of the metal tape are fraying a bit, and a tiny piece may have worked itself into the contact-pin sleeve when mounting/unmounting.

Here's the exif from one of those shots. The shot was pretty under-exposed, so the matrix metering wasn't even accurate. I guess finding the cause isn't worth it, unless someone manages to make it accurate (dial in some ev comp plus other things?) and harness it for the powers of good.
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11-29-2011, 07:47 AM   #15
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For an M42 lens (or anything where the camera can't open the aperture), this procedure should work: (But it doesn't seem worth it.)

Use whatever you have handy (I use aluminum foil and paper) to short the right contacts for your aperture range. (This includes something that sticks in to the A contact, I make a little crinkle in my foil.) Set the lens wide open, and the camera to the aperture you want. Lock exposure, and then stop down the lens to the aperture you selected.

I tried something a bit similar to get P-TTL to work with bellows, except I lied about my range and called the lens wide open even though it wasn't (since P-TTL really needs to controll the aperture). It worked well enough to make me annoyed there isn't an option to use stop down P-TTL with old lenses without jumping through hoops.
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