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07-11-2020, 12:11 AM   #1
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"all-dark" photos with K-50 viewfinder

Hey...It was around 2:30 pm, sunny day.
I started shooting with my K-50 and found almost all-dark photos output through the viewfinder while it was all fine through the LV mode.
I tried different lens and things happened again.

through LV [auto]:


through viewfinder [auto]:


through viewfinder [Av]:


BTW It worked well using [M] mode through viewfinder:


All tests above used matrix metering. Any suggestion is welcome!


Last edited by Adam; 07-11-2020 at 02:13 AM. Reason: fixed embeds
07-11-2020, 12:33 AM   #2
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QuoteOriginally posted by detour Quote
Hey...It was around 2:30 pm, sunny day.

I started shooting with my K-50 and found almost all-dark photos output through the viewfinder while it was all fine through the LV mode.

I tried different lens and things happened again.



through LV [auto]:





through viewfinder [auto]:





through viewfinder [Av]:





BTW It worked well using [M] mode through viewfinder:





All tests above used matrix metering. Any suggestion is welcome!
Light entering the viewfinder can cause metering issues. Try covering the viewfinder.

07-11-2020, 12:40 AM   #3
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That's some weird firmware display for a K-50. That aside, your problem might be aperture block related. It could also be the exposure sensor at the bottom of the mirror box housing. The lens you were using... did it have an aperture ring, or was it fully automatic, or a PLM lens? If it had an aperture ring, then it would make sense for the exposure to be fine using manual mode if the lens isn't set to Auto or A. If it's something like the 18-55 kit lens, then all images would have been dark with aperture block issue unless the aperture solenoid temporarily worked after several shots.

More testing should be done, especially after the camera has been sitting for a while.

here's a link to the aperture block thread: Dark exposure problems on K-30 or K-50? Read me first! - PentaxForums.com
07-11-2020, 03:50 AM   #4
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QuoteOriginally posted by detour Quote
I started shooting with my K-50 and found almost all-dark photos output through the viewfinder while it was all fine through the LV mode.
I tried different lens and things happened again.
Very typical symptoms for aperture-block-failure, also called dark-image-syndrome

The solenoid of the diaphragm-control-block is stuck!

In LV the solenoid actuates twice but it is stuck the first actuation.

Because the solenoid actuates twice and the mirror goes down this releases energy, the solenoid gets those extra milli-amperes which brings it to release when actuating this second time.
This is why in LV it still works, even if metering is not acurate. But after a while it fails as well in LV!



QuoteOriginally posted by detour Quote
BTW It worked well using [M] mode through viewfinder
Because the solenoid is not in action in M-Mode!

You can do those tests:
Detection of aperture block/diaphragm-block failure/stuck solenoid K-30, K-50, K500 - PentaxForums.com
(well, actually you did them already kind of)

and then apply:
Manual solenoid replacement Pentax K30 / Discharge flash-condenser / Solenoid choice - PentaxForums.com



Last edited by photogem; 07-11-2020 at 03:57 AM.
07-11-2020, 03:58 AM   #5
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From your photos, there's around a four-stop difference in exposure between the LV and viewfinder shots (AV) - shutter speed 1/6 rather than 1/125 - which is possibly why the auto and AV viewfinder shots look dark. Same exposure in viewfinder manual as in LV (1/6 second) which is why that one looks ok. We'd need to know exactly which lenses you were using to try to help further, I think.
07-12-2020, 06:11 AM   #6
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He tried different lenses and had the same problem there.
Symptoms are so typical and 99% likelyhood failure of the solenoid.
07-12-2020, 06:15 AM   #7
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QuoteOriginally posted by photogem Quote
He tried different lenses and had the same problem there.
Symptoms are so typical and 99% likelyhood failure of the solenoid.
The metering is different though. He seems to have the camera on a tripod so light could be entering the viewfinder.

07-12-2020, 06:34 AM   #8
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I can't see a tripod?

07-12-2020, 06:38 AM   #9
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QuoteOriginally posted by photogem Quote
I can't see a tripod?
Hmm you could be right but the metering is definitely different. If it was aperture block wouldn't the metering be the same?

07-12-2020, 10:27 AM   #10
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I think we have to wait what our new member comes up with.
Problem is, that some ask a question, members answer (or pretend to answer) but then there is zero reply, such as with this one:
DA 50mm 1.8 aperture stuck after drop - PentaxForums.com
07-12-2020, 10:56 AM - 1 Like   #11
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That's a little rude; we're only looking for clarity.
07-12-2020, 09:40 PM   #12
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QuoteOriginally posted by microlight Quote
That's a little rude; we're only looking for clarity.
What / which part is a little rude?
07-12-2020, 11:30 PM   #13
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'...answer (or pretend to answer)'
07-13-2020, 04:07 AM   #14
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QuoteOriginally posted by microlight Quote
'...answer (or pretend to answer)'
That wasn't coined to anybody here but just in general.
Everybody here tried just to help
07-13-2020, 09:06 AM   #15
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Okay.
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