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Forum: Troubleshooting and Beginner Help
09-28-2012, 01:25 AM
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Hi, i'm not sure if it does. Mine has now been repaired twice (under warranty) with a replacement of the shutter/diaphragm unit. That has almost done the trick - it only "flop" on maybe one shot out of 200, rather than 1 out of 10. One "fix" you can try if it is out of warranty is to tape over the contacts on the problematic lens (if it is a manual non-"A" lens it doesn't make any difference anyway) - that seemed to work for most of mine (similarly, any m42 lenses whose body does not make contact (like a Helios 58mm) - no problem at all.
Worth a try.
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Forum: Pentax K-r
06-27-2012, 05:28 AM
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Thanks. I had seen this explanation before (might have been you yourself). At first I thought it might be something to do with the aperture lever, which is why I tested it with no lens (and thus no aperture lever) but just the metal K mount. The k mount on its own produces the flop, and covering the contacts in tape stops it.
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Forum: Pentax K-r
06-27-2012, 01:38 AM
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HI all
I posted a while back about weird mirror flops on the k-r. It was sent off and "repaired" but still exhibited mirror flops but only on particular lenses.
It didn't seem to be anything to do with battery or battery charge level (there are threads for the K5 on this).
As an experiment I tried putting the mount from some of the "difficult" lenses onto the camera without the lens. This triggered the weird flop, or the mirror not returning to its proper position during its cycle.
So it couldn't be anything to do with the lens itself.
I also discovered that if I tape over the contact pins - no flop.
So, it looks like some kind of short circuiting.
Any ideas for a fix (other than sending it back again and being without camera for 6 weeks)?
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Forum: Troubleshooting and Beginner Help
05-17-2012, 11:31 AM
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I've done a bit more detective work: the lenses that are most problematic differ from the unproblematic ones in the way that the aperture levers move. I have a 35mm F3.5 manual - it's impossible to make it do the "flop". Two things: (i) The aperture lever is stiff (it works though). (ii) When it is fully open there is no play at all in the lever.
The lenses that are worst have very loose aperture levers, and, the very worst ones are ones that when the aperture is fully open, there is still play in the lever (the worst of all, the Kiron 28mm, has 100% play when fully open) an intermediate one (Pentax M 135mm) has some play. So, the amount of "flopping" seems to be proportaional to the looseness and the "play" in the aperture lever.
I don't know enough about the mechanism to now work out how the looseness and play would increase the chance of double flopping, but it seems to be too much of a coincidence not to be relevant. Any ideas?
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Forum: Troubleshooting and Beginner Help
05-15-2012, 01:18 PM
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I think you may be right - just didn't want to be without it for another month . . . .
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Forum: Troubleshooting and Beginner Help
05-15-2012, 12:58 PM
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Some more details, more puzzles -
I've posted a video on
Youtu.be
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src="https://www.youtube.com/embed/LFeERRBczco?controls=1" allowfullscreen>
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of the mirror flops.
The k-r is just back from repair for random uncontrolled flops "diaphragm mechanism replaced"
no flopping at all with fully auto lenses - only with manual, and "flop" rate varies from lens to lens
no flop with these lenses on the K100, but it turns out they have a different mechanism (the mirror doesn't cycle in optical preview)
On the "good" lenses the optical preview cycles the mirror on RELEASE of the green button (depress button steps down aperture, then mirror flop on release)
On the manual lenses (which is where you need the preview) depress button steps down aperture AND cycles mirror, and then cycles again on release
On some lenses it will also flop after the end of the video preview (i.e. couple of seconds after picture), on others will flop again when you switch it off.
Sometimes the mirror simply jams in the "up" position, and won't fall until powered off.
Because the K100 has a different mechanism, I can't really tell with this is a problem with the lenses or not - my old Pentax A and M lenses vary, the 50mm f2 seems OK, but the 135mm F3.5 sets it off now and again; worst offender is the Kiron 28mm F2 (pentax K mount), the Sigma 24mm F2.8 is close second. No problem at all with old M42 lenses, as they don't stop down and don't seem to trigger the "flop".
If it is the lenses, then it's a pain not to be able to use them reliably (when they worked fine on the K100) - I worry that this is a sign of some other problem with the mirror/aperture mechanism.
Any detectives out there who can work this out?? Much appreciated.
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Forum: Troubleshooting and Beginner Help
05-14-2012, 11:25 AM
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Thanks Adam - i've been looking around the forum and some seem to think that the k-r mirror is meant to.
There is a thread here
"The K-r has no aperture motor (the little bump in the K-5 body on the right side (left if you look onto the lens) of the mirror box. Therefore, it needs a second source to pull the aperture spring back. It is all part of a single mechanics which rewinds the shutter curtains, rewinds the mirror and pushes the mount's aperture lever. The K-7/5 needed to get an entirely new mirror box (new dampened mirror, new shutter, new aperture motor) to separate functions."
What I find a bit odd is that the old K100D doesn't seem to need the mirror to do this.
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Forum: Troubleshooting and Beginner Help
05-14-2012, 09:08 AM
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Hi -
Quick query - should the mirror flop when using the green button optical/DOF preview on a k-r? It does so every time (sometimes more than once).
It does not do so on my K100D - is this a different design or a problem (the camera has just returned from repair for, uhhm, uncontrolled mirror flopping!)
best,
Neil
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Forum: Pentax K-r
05-14-2012, 08:15 AM
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Thanks - does anyone know if the k-r and the k100 have different aperture control mechanisms (if the K100 is stronger, or, built differently, that might explain it). Also - any way to test that this is where the problem is, without sending it back for repair?
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Forum: Pentax K-r
05-14-2012, 05:55 AM
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Hi
My k-r recently had to go back for repair - it developed the uncontrollable mirror flop problem (mirror flop whenever any button was touched).
It has been repaired (under warranty) and that problem has gone. But there is still a mirror flop problem though much less frequent.
(a) With some lenses, using DOF preview involves a "double flop" - where the mirror goes up and down quickly, and the aperture opens/closes quickly. This never happens with the same lenses on my old K100D.
(b) With some lenses (again, no problem on the K100) - if used in "A" mode, and opened up to F2.8, the mirror does an extra "flop" a couple of seconds after the shutter. Weirdly, it only does this in some orientations (i.e., won't do it if the camera is held upside down).
Is this an electronic problem, or more likely to be a mechanical glitch in the aperture lever (e.g, for all I know it might be "slipping", but not on the K100D)
I can still send it back for another look but if there is a simple fix, would save me being without the k-r for a few weeks.
best,
Neil
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