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05-06-2019, 07:42 AM   #1
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Strange K-5 behaviour

I haven't heard of the feared aperture block failure regarding K-5, but I wonder if that's what I am experiencing. Strange behaviour started a couple of weeks ago when I adapted an Exakta mount lens. I suspect the adaptation did not go well because the lens was close focusing by a good 10cm. Because of that, I started using it in live mode, and it worked well. Until the following started happening: the camera would switch off live mode when I would focus the lens. If I am not focusing the lens, LV is on. When I start focusing it, it goes off. I can use live mode (and did yesterday) with other lenses with no problem, but not with that modified lens...

Speaking of yesterday, I was shooting bracketed exposures and one series of 5 shots had 4 black ones and 1 severely underexposed. It was mostly black with some reddish outlines at the bottom. I was using a 10 stop ND filter early in the morning (didn't have anything else at hand) and because of that, exposure times were long. I also had a low battery, so I attributed the series of black exposures to those two facts. But then later in the day I had another black frame.

Any theories about what might be going on?

05-06-2019, 08:20 AM   #2
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any similar behaviors with other lenses mounted?
05-06-2019, 09:00 AM   #3
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QuoteOriginally posted by pepperberry farm Quote
any similar behaviors with other lenses mounted?
Nope. Although I only use LV with ND filters, but I used ND filters all morning yesterday and didn't have any problems. Or last weekend, which was also after my LV problems with exakta lens started.
05-06-2019, 09:34 AM   #4
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QuoteOriginally posted by IgorZ Quote
Strange behaviour started a couple of weeks ago when I adapted an Exakta mount lens.
QuoteOriginally posted by IgorZ Quote
Until the following started happening: the camera would switch off live mode when I would focus the lens. If I am not focusing the lens, LV is on. When I start focusing it, it goes off. I can use live mode (and did yesterday) with other lenses with no problem, but not with that modified lens...
Details, please. Did you adapt to M42 or K-mount? Which Exakta-mount lens?

QuoteOriginally posted by IgorZ Quote
Speaking of yesterday, I was shooting bracketed exposures and one series of 5 shots had 4 black ones and 1 severely underexposed. It was mostly black with some reddish outlines at the bottom. I was using a 10 stop ND filter early in the morning (didn't have anything else at hand) and because of that, exposure times were long. I also had a low battery, so I attributed the series of black exposures to those two facts. But then later in the day I had another black frame.
This is probably not related to the other stuff above. Bracketing uses the exposure compensation feature and may produce strange results depending on exposure mode and the bracket order.


Steve

05-06-2019, 10:24 AM - 1 Like   #5
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Is this particular lens mount shorting out the electrical contacts on the body?
05-06-2019, 10:57 AM - 2 Likes   #6
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QuoteOriginally posted by pentasonic49 Quote
Is this particular lens mount shorting out the electrical contacts on the body?
This is probably the problem.

If the Exakta mount is not very conductive or is a bit loose, the lens will lose electrical contact wit the camera. The camera will think the lens was removed and drop out of LV mode to protect the mirror, shutter, and sensor.

As for the exposure issues with an ND filter, that can occur if you meter through the lens but don't have your eye or the little plastic shield covering the viewfinder eyepiece. Light can come in through the eyepiece and fool the meter.
05-06-2019, 11:04 AM   #7
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QuoteOriginally posted by stevebrot Quote
Details, please. Did you adapt to M42 or K-mount? Which Exakta-mount lens?



This is probably not related to the other stuff above. Bracketing uses the exposure compensation feature and may produce strange results depending on exposure mode and the bracket order.


Steve
Enna Munchen Ennalyt adapted using the RioRico method of gluing M39-M42 adapter over the existing mount and then using M42-K mount adapter

---------- Post added 05-06-19 at 11:07 AM ----------

QuoteOriginally posted by photoptimist Quote
This is probably the problem.

If the Exakta mount is not very conductive or is a bit loose, the lens will lose electrical contact wit the camera. The camera will think the lens was removed and drop out of LV mode to protect the mirror, shutter, and sensor.

As for the exposure issues with an ND filter, that can occur if you meter through the lens but don't have your eye or the little plastic shield covering the viewfinder eyepiece. Light can come in through the eyepiece and fool the meter.
Hmm, I wonder if that's the problem. I have a Trioplan 2.8/100 that has this bracket over the mount (I think it's used with Exakta cameras). Because of that bracket I can't fully turn the lens when mounting it on the camera. I haven't tried using this lens in LV mode as it focuses just fine with the viewfinder. If switching off LV mode was caused by loose lens, I bet that Trioplan would be it. I'll check it out tonight. Thank you for the suggestion!

---------- Post added 05-06-19 at 11:08 AM ----------

QuoteOriginally posted by pentasonic49 Quote
Is this particular lens mount shorting out the electrical contacts on the body?
Thank you! Will investigate further tonight.
05-06-2019, 11:27 AM   #8
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QuoteOriginally posted by photoptimist Quote
If the Exakta mount is not very conductive or is a bit loose, the lens will lose electrical contact wit the camera. The camera will think the lens was removed and drop out of LV mode to protect the mirror, shutter, and sensor.
I can't say for the K-5, but my K-3 is quite happy to do live view with a non-conductive mount or with no lens at all attached.


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05-06-2019, 11:32 AM   #9
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QuoteOriginally posted by pentasonic49 Quote
Is this particular lens mount shorting out the electrical contacts on the body?
QuoteOriginally posted by IgorZ Quote
Enna Munchen Ennalyt adapted using the RioRico method of gluing M39-M42 adapter over the existing mount and then using M42-K mount adapter
I am not sure which contacts pentasonic was referring to, but I am curious as to whether the tangs on the Ennalyt are shorting out the power contacts in the mirror box. Some Ennalyt models have fairly robust versions of the Exakta mount (thick tangs). If they are contacting those pins at all, it is not a good thing, particularly if the pins should get bent. This is even a hazard with the aperture actuator pin on some M42 lenses.


Steve

Last edited by stevebrot; 05-06-2019 at 11:44 AM.
05-06-2019, 11:38 AM   #10
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QuoteOriginally posted by stevebrot Quote
I am not sure which contacts pentasonic was referring to, but I am curious as to whether the tangs on the Ennalyt are shorting out the power contacts in the mirror box. Some Ennalyt models have fairly robust versions (thick tangs) of the Exakta mount. If they are contacting those pins at all, it is not a good thing, particularly if the pins should get bent. This is even a hazard with the aperture actuator pin on some M42 lenses.


Steve
is there a way to find out if that's the case? I haven't had problems with the lens (aside from close focusing)...
05-06-2019, 11:57 AM   #11
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I'm not sure about the conductivity as I only have a Cosina 50-1.9 K mount lens and a set of K mount extension tubes, which all have non conductive anodised surfaces on the mounts. The live view works with the Cosina 50 when in Tv, but I don't think the K5 will playback more than the first frame, (I don't use LV normally). A check with a meter will tell if the mount is conductive of not.
As for the other problems, all I can suggest is to do a reset and then go through the menus adding all your settings afresh. And keep your fingers crossed.

Last edited by pentasonic49; 05-06-2019 at 12:06 PM.
05-06-2019, 12:03 PM   #12
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QuoteOriginally posted by IgorZ Quote
is there a way to find out if that's the case? I haven't had problems with the lens (aside from close focusing)...
The lens is reportedly causing your camera to abruptly drop its mirror and close its shutter.

What I would do is to:
  • Closely examine the two power pins just inside the camera's mount throat at the bottom of the mirror box
  • Check too for evidence of abrasion on the adjacent portions of the mirror box
  • With the lens off the camera, evaluate the position of the tangs as they would be during a normal mount
  • Measure the depth of the furthest intrusion of the tangs into the mirror box (flange face to rear tang surface). Compare that to the depth of the contact pins in the mount. The pins' tops are not particularly deep (~7mm) and the clearance of my Exakta-mount lenses would be pretty slim.
It is hard to say whether the pins on your camera are energized during live view, but even if they are not, they are not something we want to be pushing around with blunt objects.


Steve
05-06-2019, 12:54 PM - 1 Like   #13
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QuoteOriginally posted by stevebrot Quote
I can't say for the K-5, but my K-3 is quite happy to do live view with a non-conductive mount or with no lens at all attached.


Steve
Both the K-5 and the K-1 do live view with no lens attached.

However.... if you mount a lens on a K-5, put the camera in LV, and then dismount the lens, the K-5 pops out of LV mode. The behavior occurs with both newer lenses (with the multi-point contacts) and older manual lenses that just have a conductive mount ring. A loose lens and intermittent contact between the K-5 and lens will cause erratic LV behavior.

EDIT: The K-1 is a bit different... It will go into LV mode with or without a lens. But it does not drop out of LV mode if you dismount the lens.

Last edited by photoptimist; 05-06-2019 at 01:22 PM. Reason: Updated for K-1's differences
05-06-2019, 02:06 PM   #14
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QuoteOriginally posted by photoptimist Quote
However.... if you mount a lens on a K-5, put the camera in LV, and then dismount the lens, the K-5 pops out of LV mode.
That was the sequence I started with on the K-3 and it did not drop out of LV. If the K-5 behavior is different, that may be an explanation if the paint on the Ennalyt is patchy.


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05-06-2019, 03:32 PM   #15
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I don't think the problem is contact or no contact, but intermittent contact which is happening when you start turning the focusing ring -- if it changes state from one to the other it will switch off LV.
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