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09-10-2011, 08:54 AM   #1
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Strange K-r behavior

Hi, well strange things started to happen to my (actually my GF's) K-r too. When using the 50mm SMC Takumar in AV mode, sometimes the mirror randomly flips without taking a picture, and the EXIF data turns out strange. For example, check out this picture:


It's clear that I had the Takumar on, but now take a look at the EXIF:
Camera Pentax K-r (ok)
Exposure 0.017 sec (1/60) (ok)
Aperture f/2.8 (!!!!)
Focal Length 50 mm (ok)
ISO Speed 800 (ok)
Exposure Bias 0 EV (ok)
Metering Mode Multi-segment (!!!)
Lens A Series Lens (!!!!)
Lens ID 2 0 (!!!)
I think some contacts on the camera mount are shorted in a way that causes this behavior. It should be noted that I have only encountered the problem with the 50mm Takumar in Av mode.

09-10-2011, 09:24 AM   #2
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Did you try..?

Did you try cleaning the contacts - both camera and lens?
09-10-2011, 10:23 AM   #3
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After doing so, it seems the camera has stopped tagging the aperture in the pictures, but I wonder for how long.
09-10-2011, 10:29 AM   #4
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You're using a Tak, not a lens with A-type contacts, so the camera does not receive info from the lens. Depending on the adapter used, and whether the lens base is conductive, the camera CPU responds in odd ways. You shouldn't be surprised to see that bad data; it's essentially noise.

The camera knows the shutter speed and ISO and EV comp and various other in-camera stuff. The camera knows the focal length -- if you informed the SR'bot. But the camera knows nothing else about the lens nor any lens-related stuff. ERROR - INSUFFICIENT DATA. Pity the poor CPU...

09-10-2011, 11:39 AM   #5
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If it's a fully manual lens, the camera cant get the aperture setting, for example, because its just a ring and doesnt send the information to the camera. I guess the camera tries to get the information, then the number is kind of random...i dont know...
09-10-2011, 04:08 PM   #6
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Trying to use a fully manual lens in Av mode is likely part of the problem (but I think the contacts are playing up too). You're essentially telling the camera to expect aperture data when it can't. You should use M for manual lenses.
09-15-2011, 08:37 PM - 2 Likes   #7
wax
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My opinion is there is a non compatibility between some lenses and camera electronic. Mirror flops happens to my K-r on these casses:
Pentax 50mm f1.4: never
Pentax 18-55mm kit lens: never
Pentax 35mm f2.4: never
Pentax 135mm f2.5: never
Sigma 18-200mm f3.5-6.3: never
Vivitar 70-210mm f2.8-4.0: usually
Samyang 18-28mm f4-4.5: sometimes
Carl Zeiss 50mm f1.7 contax mount converted to PK: allways
Rikenon Ricoh XR 28mm f2.8: never

So, on my experience using different kind of lenses, mount material, wrong pin connections, or metering reading, donīt really knows for sure, produce the effect of erratic mirror flops.

Last edited by wax; 09-16-2011 at 03:24 PM. Reason: actualization 16709/2011
09-16-2011, 10:35 AM   #8
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Very useful informations. Thanks wax

09-16-2011, 11:41 AM   #9
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Why did you actually mention all those lenses if you say that strange behavior never occured with them?
09-16-2011, 11:47 AM   #10
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QuoteOriginally posted by kcobain1992 Quote
Why did you actually mention all those lenses if you say that strange behavior never occured with them?
More information is always better. If there's a trend on which lenses are (or are not) causing this issue, knowing which are not affected is just as important as knowing which are.

I'll have some new info on this later, but I need to take some pictures first. I've figured out why mirror flops are happening with some old lenses.

Edit: Probable solution here.

Last edited by Philoslothical; 09-16-2011 at 03:54 PM.
09-17-2011, 03:29 AM   #11
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I'm inclined to believe it's a problem with the camera itself.
I had the same issue with a Helios 44-m; a lens that the majority users on this forum report enjoying without issue. Mounted on my K-R with the official Pentax M42 adapter and metering with the green button, the mirror flopped intermittently at first. My camera then became unusable with the shutter firing while pressing any button; even without the lens attached. I would of attributed this to the lens but unfortunately I'd experienced the same problems using my Voigtlander Color Skopar 20mm f/3.5 SL II.
I've returned my camera for replacement in the hope I wont have any further issues.
09-20-2011, 01:42 PM   #12
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I had the same issue with a converted Nikkor 28/2.8 Ai-s last night...
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