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06-07-2016, 06:35 PM   #1
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New K-50, repaired once replacing the diaphramg control block, still defective?

My 60 day old K-50, only 2 days out of warranty started giving me dark pictures thru the viewfinder, and immediately afterwards---as in fractions of a second later, the exact same picture thru Live View would be fine. I noticed that the parameters were changing when I switched between viewfinder and live view, moving nothing, holding the camera steady, and the ISO, or shutter speed, or F stop would change just by switching between viewfinder and live view, done in fractions of a second.

Per Pentax, I sent this to Precision Camera on my $16 dime, they replaced a Diaphramg Control Block [their spelling].

Now it is doing the same thing---dark thru viewfinder, then immediately fine thru the live view. See pictures below.

Am I doing something wrong?

If not, should I endure another repair? Is the diaphragm control block causing this error? I want a different camera, as I suspect something is blowing the diaphragm control block, and it will always blow. I will call Pentax, again, tomorrow morning.

Your thoughts?

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06-07-2016, 06:52 PM   #2
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Not a happy situation. My wife's 2-year-old K-50 is at 5K clicks and no issues, yet. Out of warranty, so it will be a different model for her if this happens.

Looks like you may be sending it back?
06-07-2016, 10:14 PM   #3
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QuoteOriginally posted by RedSky Quote
If not, should I endure another repair?
Which is more painful, enduring shipping and fix at their expense or not getting your money's worth from your camera + your previous $16 shipping?

QuoteOriginally posted by RedSky Quote
I want a different camera, as I suspect something is blowing the diaphragm control block, and it will always blow.
There is not harm in asking. Good luck. With the initial failure at 60 days, the store might have also been a good option. If you bought from Costco, they will allow a return for full credit for some time after the purchase (at least a year and sometimes longer).


Steve
06-08-2016, 05:51 AM   #4
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Wow, I posted this to Amazon last night, and they are replacing the camera. Incredible customer service I would now say. Hope this one is much, much better.

06-08-2016, 10:17 AM   #5
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QuoteOriginally posted by RedSky Quote
Wow, I posted this to Amazon last night, and they are replacing the camera. Incredible customer service I would now say. Hope this one is much, much better.
Amazon or Pentax? Either way, it is a great outcome


Steve
06-08-2016, 06:22 PM   #6
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QuoteOriginally posted by RedSky Quote
I noticed that the parameters were changing when I switched between viewfinder and live view, moving nothing, holding the camera steady, and the ISO, or shutter speed, or F stop would change just by switching between viewfinder and live view, done in fractions of a second.
If the parameters change when switching to live view that suggests that it's not the diaphragm block at fault but just a discrepancy between metering through the viewfinder and in live view. This seems to be normal behaviour as certainly my K-r produces brighter images in live view -- I believe it's due to the camera metering off the sensor rather than the prism. The posted pictures don't look typical for aperture block failure either. When my wife's K-x had the aperture problem it would produce vitually completely black frames outdoors unless the sensitivity was cranked way up.

Anyway, what I'm saying is it's good to hear that you're getting a replacement camera but don't be surprised if the new body also exposes a little darker through the vf compared to liveview...
06-09-2016, 04:19 PM   #7
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QuoteOriginally posted by Suzhouren Quote
If the parameters change when switching to live view that suggests that it's not the diaphragm block at fault but just a discrepancy between metering through the viewfinder and in live view.
Yes, this is expected behavior. The two systems use different means to arrive at a reasonable exposure. In some ways live view has more information to work with (the whole image sensor serves as the detector), but in other ways is not able to fully evaluate the light within the frame to the same extent as the main viewfinder meter (the main meter has greater dynamic range). As a result a particular scene may meter differently in live view than with the main meter. One is not more accurate than the other* and both use some form of evaluative metering, though they may give different readings.**

You may expect similar differences (main meter vs. live view) for all brands of dSLR cameras.


Steve

* Both should give the same exposure for an 18% gray card occupying the full frame. That exposure should result in a centered histogram on a test image. That being said, accuracy is not the same as appropriate and what is appropriate is sometimes not clear. With automated exposure systems it is always a best guess situation.

** Different measurement strategies may be fully valid yet provide different answers. I have a hand-held meter capable of both incident and reflected light readings. It is not unusual for the two methods to vary 1-2 stops from other while the readings from both are quite valid.
06-11-2016, 10:20 AM   #8
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I did not know one could amend, or add to an original thread. Thanks to all who offered help.

Amazon replaced the camera, which I thought was very nice of them. I guess I will just keep one of the two cameras. Two Pentax representatives were unable to tell me that this was / is expected behavior, One call on the original camera and a second call on the repaired camera. First rep said sent it to repairs, the second rep said the repairs must not have worked, send it back a second time.

A second source of frustration is that Precision Camera for some reason thought that a Diaphramg Control Block was needed, and from my perspective, changed nothing.

I just thought that in the digital world a properly exposed picture say at ISO 100, 1/60 and F8, would be independent of the framing method. I thought the framing methods were just two different avenues to use to "frame the shot" and that both would return me the same settings. If this is not true, then I can manually adjust the viewfinder and take multiple exposures and hope for the best, or basically just disregard the viewfinder and use Live View all the time.

Thanks for answering the question I posed: "is this standard for all DSLR cameras", and it seems to be yes.

thanks all

06-11-2016, 08:30 PM   #9
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QuoteOriginally posted by RedSky Quote
I just thought that in the digital world a properly exposed picture say at ISO 100, 1/60 and F8, would be independent of the framing method.
Your statement above is absolutely true in both the digital and film world. However, you used two different metering systems that read the scene differently and which provided two different exposure settings. That is why the photos themselves are different. If you had used M mode and set the camera to 1/60s, f/8, ISO 100 manually, the exposures would have been identical for both optical viewfinder and live view.


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06-11-2016, 08:51 PM   #10
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yup the dreaded diaphragm block failure, it seems to dominate this forum. But that is totally normal according to some guys on this board ?
06-11-2016, 09:09 PM   #11
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QuoteOriginally posted by niceshot Quote
yup the dreaded diaphragm block failure, it seems to dominate this forum. But that is totally normal according to some guys on this board ?
Redsky has posted the one problem several times and you have responded unaware it's the same person.

06-11-2016, 09:37 PM   #12
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QuoteOriginally posted by niceshot Quote
yup the dreaded diaphragm block failure, it seems to dominate this forum. But that is totally normal according to some guys on this board ?
Perhaps it would help if you read the thread. There was never anything wrong with the camera. The title is misleading, but innocently so.


Steve
06-11-2016, 10:00 PM   #13
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QuoteOriginally posted by clackers Quote
Redsky has posted the one problem several times and you have responded unaware it's the same person.
A quick look at user niceshot's post history indicates that he is on a crusade of sorts. It takes all sorts, I guess.


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06-11-2016, 10:21 PM   #14
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QuoteOriginally posted by stevebrot Quote
A quick look at user niceshot's post history indicates that he is on a crusade of sorts. It takes all sorts, I guess.


Steve
Oh, dear.

An axe grinder, no matter the merit of the topic being discussed, is tedious.

06-12-2016, 12:46 PM   #15
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I would disagree, I am just trying to determine if I have two defective cameras, and have gotten more hatred here than help. Yes, I posted to too many places in my frustration, but the hatred here has been over the top. I guess it is easy to be so on the keyboard.

I am still no closer to an answer than I was when I started. Is it a diaphragm block failure, or is the camera perfect?

Keep your replies to yourself, one camera goes back tomorrow, and I will keep one and work around it or toss it in the trash. What a mistake it was even coming to this forum. I am done. May the future years treat you all well.
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