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12-10-2018, 05:00 AM   #1
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Dark images

Pictures taken with my K-70 are coming out very DARK. I've checked the exposure settings and Exposure Compensation, but nothing wrong. Camera was OK last week and just started giving dark pictures yesterday. I,ve been through my instruction book and even tried the Reset button to give the 'original' settings, still no joy!
It looks like there is a software fault somewhere. Has anyone had this happen to them? Please Help!

12-10-2018, 05:12 AM   #2
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Could be the problem our K-30s and K-50s are experiencing. Aperture block failure, that's how it starts, black frames. Is this how it is with your K-70?

Might want to read here:

https://www.pentaxforums.com/forums/151-pentax-k-30-k-50/370666-dark-exposur...-me-first.html

And there has been other reports of the K-70 experiencing the same problem.

https://www.pentaxforums.com/forums/193-pentax-k-70/377096-k-70-underexposed-photo-reports.html

Last edited by photolady95; 12-10-2018 at 05:20 AM.
12-10-2018, 11:20 AM   #3
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Welcome to the Forums!

Could ya post sample photo that includes exif data?
12-10-2018, 11:36 AM   #4
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QuoteOriginally posted by Eric Hall Quote
Pictures taken with my K-70 are coming out very DARK. I've checked the exposure settings and Exposure Compensation, but nothing wrong. Camera was OK last week and just started giving dark pictures yesterday. I,ve been through my instruction book and even tried the Reset button to give the 'original' settings, still no joy!
It looks like there is a software fault somewhere. Has anyone had this happen to them? Please Help!
@FozzFoster is correct. A dark image posted here would be very informative.

@photolady95 is also correct; we have not heard very many Dark Image Syndrome cases reported here, but DSI takes time to develop. The 'gold standard' diagnosis procedure is to observe the aperture mechanism {"iris"} as you take a photo - if the body thinks the aperture is set to the widest value available, the "iris" should remain wide as you take the photo ..... it will shut tight if you have an aperture control issue
QuoteOriginally posted by stevebrot Quote
Diagnostic is to set to M mode with aperture set wide open with a 1s shutter speed, AF off. Observe the lens from the front while pressing the shutter button. If the lens stops down, there is an aperture control problem. Whether it is the aperture control block requires a more intensive diagnostic; fault may be in the camera electronics.


12-10-2018, 12:05 PM   #5
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QuoteOriginally posted by photolady95 Quote
And there has been other reports of the K-70 experiencing the same problem.
It would be good to note that none of the reports to date (5 total) have been confirmed as aperture block failure, meaning that a camera when sent for authorized service was repaired by replacement of the diaphragm control block (the component that failed on the K-30/K-50). I know it is a small matter, but the implications are important in that broad claims have been made regarding the K-70 and vulnerability to this sort of problem. So far, the reports thread has been pretty quiet with none of the original reporting members having closed the circle for their cameras.


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12-10-2018, 12:15 PM   #6
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QuoteOriginally posted by Eric Hall Quote
Pictures taken with my K-70 are coming out very DARK.
Welcome to the Pentax Forums!

Hopefully, this problem can be resolved as something other than a hardware failure of your camera.


Steve
12-11-2018, 06:54 AM   #7
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Dark Images from K-70

Hello Pentax Forum, thanks for the reply. After browsing various threads on 'Dark Images etc. I found a link, similar to the one you sent me, about 'Aperture Blocking'. I now think this is the most likely cause of my problems, because I performed the 'iris' test on 'Manual' setting for 2 seconds at full aperture, and observed the iris closing down fully when I pressed the shutter.
Furthermore, my K-70 is still under 12 Warranty, so I am going to return it for repair. Thanks for your help.
Images taken yesterday on my K-70 are attached. These were taken as RAW DNG's and converted to jpg resolution 72 and quality 8. No corrections applied.
Attached Images
View Picture EXIF
PENTAX K-70  Photo 
View Picture EXIF
PENTAX K-70  Photo 
12-11-2018, 07:03 AM   #8
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You're welcome for the help. Your camera being under warranty will get it fixed for free.

12-11-2018, 09:22 AM   #9
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QuoteOriginally posted by Eric Hall Quote
I performed the 'iris' test on 'Manual' setting for 2 seconds at full aperture, and observed the iris closing down fully when I pressed the shutter.
I am glad you are still under warranty. Let us all know what they do for the repair.


Steve
07-28-2019, 02:42 PM   #10
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Is this It?

So, just happen to grab my K70 to snap some pics. I used it yesterday, no problems and then this happens. I had the k50 prior and replaced it with the k70. What are the chances this happens again!!!
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PENTAX K-70  Photo 
07-29-2019, 12:18 PM   #11
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QuoteOriginally posted by LucyGoosey Quote
So, just happen to grab my K70 to snap some pics. I used it yesterday, no problems and then this happens. I had the k50 prior and replaced it with the k70. What are the chances this happens again!!!
Based on user reports on this site, the incidence (not the same as probability) of K-50 style aperture control failure on the K-70 is pretty low. The incidence of poor exposure from other causes is quite a bit higher. The original post at the beginning of the thread linked below has instructions for determining if your K-70 body is having trouble with aperture control.
K-70 Underexposed Photo Reports - PentaxForums.com
The EXIF for your posted photo above shows that the mode dial was in the Auto position and that the camera chose Portrait as the appropriate preset for your subject and that the flash was turned off. Possible causes for the underexposure include:
  • Flash not used when indicated by viewfinder display
  • Sticky/lazy lens aperture mechanism (may be tested by "flicking" aperture actuator on rear of lens while watching the aperture motion...movement should be snappy with no hesitation or sticking)
  • Physical damage to lens aperture actuator coupling (bent lever or similar)
  • Defective camera metering
  • Defective shutter mechanism
  • Problem with aperture control by body
One can check for the last point by doing this simple test:
QuoteOriginally posted by stevebrot Quote
To test for Aperture Control Failure/Issue:

The so-called gold standard for diagnosing an issue with aperture control is to put the camera in M mode (auto ISO off, aperture ring not being used) with aperture set wide open and shutter speed at something slow (e.g. 1-2 seconds). Release the shutter while observing the aperture opening through the front of the lens. Anything other than the aperture remaining wide open is indication of a problem with the controller. If the problem has been intermittent, it may help to do the test after a period of non-use. Even one failure of this type is significant.

Steve
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