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K-70 Underexposed Photo Reports
Posted By: stevebrot, 10-05-2018, 02:16 PM

As of today, 28 December 2019, I will no longer be maintaining this report page.

The incidence is sufficiently low that it hardly makes sense, but it has been an interesting experience.

Steve

***************************************************************************************************

There have been a couple of recent threads regarding gross underexposure (essentially black) on some or all photos. While it is not fully clear whether these reports are related or (shudder) whether there is an emerging problem similar to the aperture block failure common to the K-30/K-50 models, it seems reasonable to provide a clearinghouse thread in an attempt to determine who is having problems and the evident point of failure. For the sake of clarity and accountability, it would be good to limit experiences to those of our users and not reference claims from other forums or rumor sites.

NOTICE: This thread is curated and keeping track of pertinent reports and updates will be easier if we abide be a few simple rules. Please use this thread for:
  • Reports of problems with underexposed or dark frames from Pentax Forums users. Please include written details and whether you were able to confirm that it is an issue with aperture control (see below for instructions).
  • Updates regarding cause, repairs, and repair details (when known)
Do NOT use this thread for:
  • Discussion of the aperture control block problem on K-30/K50/K500 models or reports for any model other than the K-70
  • Troubleshooting poor exposure. A separate thread in the K-70 subforum or in the troubleshooting section of the site might work better.
  • Photos of dark frames. If it is happening, your word is enough. Photo examples, even with full EXIF, are of limited or no value for troubleshooting or confirmation.
  • Complaints about Ricoh/Pentax product or service or business practices
  • Complaints or comments about the K-70 in general
  • Complaints about repairs from authorized facilities, including: timeliness, cost, outcome, or communication
In regards to the last three points, neither Ricoh/Pentax nor the authorized repair shops they contract with monitor activity on the Pentax Forums site.
**********************************

To date, I am aware of the following Pentax Forums users having problems with dark frames:

User @dudesohungry (31 Aug 2018) : K70 ISO problem - PentaxForums.com
Not known if this was an aperture or other problem.

User @drumhead (17 Sept 2018) : Strange behaviour from my K-70...aperture block? - PentaxForums.com
Presumptive aperture control issue. Camera sent for warranty service.

User @CodyH (30 Sept 2018): K-70 aperture motor question - PentaxForums.com
Confirmed aperture control issue with root cause not known. Warranty service may be attempted (camera barely out of warranty). Update -- camera is being sent for service and will probably be covered under warranty.

User @RichFam (5 Oct 2018): K-70 Underexposed Photo Reports - PentaxForums.com
Confirmed aperture control issue with root cause not known at about one year post purchase. Did not seek warranty service.

User @asalwa (11 Nov 2018): K70 aperture block? - PentaxForums.com
Confirmed aperture control issue with root cause not known, August 2018. Out-of-warranty repair was performed, though it is unknown what was replaced/adjusted.

User @Eric_Hall (10 Dec 2018): Dark images - PentaxForums.com
Confirmed aperture control issue with root cause not known with camera to be sent for service under warranty.

User @fernoh123 (6 Jan 2019): K-70 Underexposed Photo Reports - PentaxForums.com. Symptoms similar to aperture control issues with other model cameras. Unknown whether repair was sought.
Confirmed Camera was sent for warranty repair with root cause confirmed as aperture control block failure by statement of work performed.

User @pentax360 (30 Jan 2019): K-70 Underexposed Photo Reports - PentaxForums.com. Dark frames on first few captures of a session. It is unknown whether the cause is due to failed aperture control.

User @SharkyCA (31 Mar 2019): K70 aperture block? - Page 3 - PentaxForums.com.
Confirmed aperture control issue with root cause determined to be diaphragm control block. Dark frames interspersed with properly exposed frames (middle two out of four effected in initial report and many in subsequent discussion). User sent camera to Sun Camera in Canada where they confirmed the diagnosis.

User @disasterfilm (16 Jun 2019) New K-70 - Metering issues between Live View and OVF - PentaxForums.com originally reported as dark frames when using optical viewfinder only. This is apparently a metering issue, but is recorded here just in case.

User @Alex74 (10 Jul 2019) K-70 Exposure issues - Page 3 - PentaxForums.com
Ambiguous Aperture actuation problems of unclear nature (based on repair report); root cause ambiguous...repair report "exchanged aperture mechanism and controller". User initially reported severely underexposed as well as overexposed frames despite no change in camera settings. Initially it was unknown whether this was a problem of lazy aperture or aperture control. Making no assumptions, I trust that the problem has been fixed. Report is retained in the interest of making as complete a count as reasonable.

User @rwhynacht (15 Aug 2019) New K-70 - Metering issues between Live View and OVF - PentaxForums.com
Confirmed aperture control issue based on repair outcome; root cause ambiguous...repair involved replacement of Aperture Control Assy and Resistor Chip. NOTE: This camera had been recently purchased.
Severely underexposed photos in auto exposure modes that, though unclear whether the issue is metering or something else, but included here just in case. The camera was serviced with report noted here.

User @tanz (23 Aug 2019) K-70 Underexposed Photo Reports - Page 7 - PentaxForums.com reports severely underexposed frames when using the optical viewfinder with live mode not having obvious problems. Likely aperture control failure based on description of stop-down behavior.

User @riverrock (9 Sept 2019) https://www.pentaxforums.com/forums/193-pentax-k-70/377096-k-70-underexposed...ml#post4721041
Confirmed Aperture Control Failure/Issue, root cause unknown. Reports severely underexposed frames with visual confirmation of inappropriate aperture stop-down.

User @davedyer (12 Sept 2019) first picture is dark - PentaxForums.com
Confirmed aperture control failure/issue, root cause unknown. Reports underexposed first frame with properly exposed frames thereafter with visual confirmation of inappropriate aperture stop-down.

User @corbinco2 (25 Oct 2019) https://www.pentaxforums.com/forums/53-pentax-dslr-camera-articles/377096-k-...ml#post4778685
Confirmed aperture control failure/issue, root cause unknown. Consistent dark frames after two years ownership confirmed as aperture control problem by visual inspection.

User @Progbusters (19 Nov 2019) https://www.pentaxforums.com/forums/53-pentax-dslr-camera-articles/377096-k-...ml#post4818734
Confirmed aperture control failure/issue, root cause unknown. Consistent dark frames after a few months ownership confirmed as aperture control problem by visual inspection. Grey market purchase with unknown warranty options. User opted to not repair and sold camera "as-is".

User @photogem (23 Dec 2019) https://www.pentaxforums.com/forums/53-pentax-dslr-camera-articles/377096-k-...ml#post4870093
Confirmed aperture control failure/issue corrected by user replacement of solenoid. Failure at after one year ownership, camera still under warranty.


**********************************


Three (initial) similar problems in less that a month's span are a potential cause for concern. Any future reports may be logged here in an effort to determine if these are isolated incidents or evidence of a larger issue. At the very least, this thread may serve to qualify claims of multiple reports from the Web regarding K-70 aperture control problems.

Note: Terminology is important and it is good to be clear on terms. Here are a few starters along with working definitions:
  • Exposure problems: images are over or underexposed. Cause may be anything from user inexperience to hardware meltdown
  • Metering issues: Bad meter readings leading to inappropriate settings
  • Dark Image Syndrome (DIS): Term coined by user @reh321 for unexplained dark frames despite correct settings
  • Aperture Control Failure/Issue: Iris opening during exposure does not reflect set value. Example: Camera is set to wide open, but exposure is made with lens stopped down to smallest opening. This sort of behavior may have many different causes as diverse as damage or failure in the lens itself and water incursion causing damage to body electronics.
  • Aperture Block Failure: This is the specific failure of the so-called aperture block solenoid used for aperture control on a wide span of Pentax SLR bodies dating back as far as the early 1980s. Failure of this component affected a large number of K-30, K-50, and K-500 bodies and was the cause of aperture control failure on those cameras. A similar unit was fitted to the K-S1 and K-S2. It is possible that the K-70 has a similar part, hence this thread.
  • Diaphragm control block : G100 Proper name and part number for the assembly that controls the aperture opening on most Pentax cameras since the early 1980s. "Aperture block" and "Aperture control block" are synonyms in common usage.
  • Diaphragm control block : G200 Proper name and part number for the assembly that controls the aperture opening on flagship models since the release of the K-7. As of 11 Oct 2018, it is not clear whether the K-70 uses this part or the G100 part above.

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 is significant.
Hopefully, there is no cause for alarm.


Steve

(...not a K-70 owner, but was heavily involved in the first wave of K-30 problems several years ago...)

Last edited by stevebrot; 12-28-2019 at 09:08 PM. Reason: Closing shop
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04-29-2019, 05:20 PM   #61
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QuoteOriginally posted by Not a Number Quote
On the German Pentaxians.de forum there is poll on failures of the K-70. Of 50 respondents 4 report failure.
K-70 wer hat (keine?) Probleme mit Blendensteuerung? ? Pentaxians

One member reports buying a used K-70 that had the failure when purchased:
erste K-70 mit defekter Blendensteuerung - Black Picture ? Pentaxians

And subsequently repairing the by filing the plunger of the solenoid:
Tutorial - Reparatur Pentax K-70 Blendensteuerung Solenoid ? Pentaxians

You can use Google Translate to get an idea of what is being posted. You need to be a registered member to see many of the photographs. If you are familiar with the aperture control block mechanism on the K-30/50 and K-S1/S2 you can see the differences in design.
In the original post, I requested:

QuoteOriginally posted by stevebrot Quote
For the sake of clarity and accountability, it would be good to limit experiences to those of our users and not reference claims from other forums or rumor sites.
This thread is intended as a clearing house for reports from our users where we can easily confirm and qualify reports. It is probably inevitable that general discussion might intrude, but I am a little concerned that I might miss on-topic posts.


Steve

04-29-2019, 07:55 PM - 1 Like   #62
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QuoteOriginally posted by SharkyCA Quote
Thanks, some of the exposures were done using manual and "tav" not all in auto. If you follow my link to the Flickr images the "exif" is present.https://www.flickr.com/photos/sharkyca/sets/72157706829697591/
Yes, my comments were made after looking at the EXIF - I guess I misunderstood what they mean by 'Auto'.
The fact remains that your photos have too many parameters varying, but from what I can see, I believe you are dealing with metering issues.

To be really useful, you need to set ISO to a fixed value, say 400, certainly not "Auto", then use either 'Tv' or 'Av' mode so that only one parameter will change at a time.
04-30-2019, 01:48 AM   #63
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QuoteOriginally posted by stevebrot Quote
"Exposure mode - Auto" in the EXIF means exposure automation. This might include P, Av, Tv, Sv, or TAv, but never B, X, or M modes.

I have not made a full tour of the examples on Flickr, but if LV exposures are always proper, it may not be an aperture block problem. Is my memory correct that we still have no visual confirmation of aperture control failure for this camera? It may be time to put this problem out for a separate troubleshooting request.

Having said that last, I will make one comment, that being that spot metering is a common cause of exposure problems, is a specialized tool and is usually inappropriate for general shooting. I don't think it is responsible for the dark frames, but is likely a cause for the overexposed shots.

Steve
You are right Steve,no confirmation on aperture failure although it now seems to be ALL LENSES!

In regards to the spot metering, I switched to it as I thought it may have been related to the "full metering" I was using, I have sent an inquiry to Precision Camera (Sun Camera Service in Toronto, authorized repair in Canada. Also if I engage FLASH, images are still under exposed

Norm
04-30-2019, 04:04 AM   #64
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QuoteOriginally posted by reh321 Quote
Yes, my comments were made after looking at the EXIF - I guess I misunderstood what they mean by 'Auto'.
The fact remains that your photos have too many parameters varying, but from what I can see, I believe you are dealing with metering issues.

To be really useful, you need to set ISO to a fixed value, say 400, certainly not "Auto", then use either 'Tv' or 'Av' mode so that only one parameter will change at a time.
reh321, I tried your suggestion of shooting with "ISO set to 400,Tv mode,also ISO Auto,100-400, Av images started to display normally, set camera back to FULL AUTO and now appears to be functioning NORMALLY

QuoteOriginally posted by stevebrot Quote
"Exposure mode - Auto" in the EXIF means exposure automation. This might include P, Av, Tv, Sv, or TAv, but never B, X, or M modes.

I have not made a full tour of the examples on Flickr, but if LV exposures are always proper, it may not be an aperture block problem. Is my memory correct that we still have no visual confirmation of aperture control failure for this camera? It may be time to put this problem out for a separate troubleshooting request.

Having said that last, I will make one comment, that being that spot metering is a common cause of exposure problems, is a specialized tool and is usually inappropriate for general shooting. I don't think it is responsible for the dark frames, but is likely a cause for the overexposed shots.


Steve
Steve, Please see above thread (reh321, I am becoming completely confused and starting to wonder if there is a possible glitch in the firmware now that the problem seems to have mysteriously RESET and the camera is back to normal.

As it is not quite sun up when I took these pics and I am going back to bed I will post more images later.

Thanks for all the help on this problem. I have added 3 photos but they are night shots, dark images but expected to be, NOT what I was getting. https://www.flickr.com/gp/sharkyca/Ti2nN9

04-30-2019, 08:58 AM   #65
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QuoteOriginally posted by SharkyCA Quote
Steve, Please see above thread (reh321, I am becoming completely confused and starting to wonder if there is a possible glitch in the firmware now that the problem seems to have mysteriously RESET and the camera is back to normal.

As it is not quite sun up when I took these pics and I am going back to bed I will post more images later.
Intermittent problems are so hard to diagnose.

This thread is not really intended for extended troubleshooting. Although it is unclear whether you have an issue with aperture control*, you clearly have a problem and it is likely that service is your best option. If may be that more than one issue is at work here and the service center can evaluate in a short period of time what would require days of online discussion.


Steve

* My understanding is that you have not been able to observe inappropriate stop-down for any of mix of camera and lens (M mode, aperture wide open, aperture control function directly observed through front of lens)
04-30-2019, 03:11 PM   #66
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QuoteOriginally posted by stevebrot Quote
Intermittent problems are so hard to diagnose.

This thread is not really intended for extended troubleshooting. Although it is unclear whether you have an issue with aperture control*, you clearly have a problem and it is likely that service is your best option. If may be that more than one issue is at work here and the service center can evaluate in a short period of time what would require days of online discussion.


Steve

* My understanding is that you have not been able to observe inappropriate stop-down for any of mix of camera and lens (M mode, aperture wide open, aperture control function directly observed through front of lens)
I agree with your post Steve,although there has not been a clear diagnosis of what I have had happening but the first indications looked like an "aperture problem" I would be open to having my posts here moved to a separate thread so as not to clutter up your original intention of "tracking k-70 aperture block" if that is possible?

Here is the response I got back from "Sun Camera" in regard to my inquiry:

Hi,
Your camera may be having an issue with the aperture block. The cost to have this issue fixed is roughly $200.

---
Thank you

Sun Camera Service
2150 Steeles Ave West
Unit 5
Concord, Ont. L4K 2Y7
905-669-6355


Awaiting your input about moving my posts!

Norm
04-30-2019, 03:34 PM - 1 Like   #67
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QuoteOriginally posted by SharkyCA Quote
Here is the response I got back from "Sun Camera" in regard to my inquiry:

Hi,
Your camera may be having an issue with the aperture block. The cost to have this issue fixed is roughly $200.

---
Thank you

Sun Camera Service
2150 Steeles Ave West
Unit 5
Concord, Ont. L4K 2Y7
905-669-6355


Awaiting your input about moving my posts!
Let's just leave them as is for now. Let me know if you send it off. It is a shame that you fall through the cracks as far as warranty service goes.


Steve

04-30-2019, 06:48 PM   #68
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QuoteOriginally posted by stevebrot Quote
Let's just leave them as is for now. Let me know if you send it off. It is a shame that you fall through the cracks as far as warranty service goes.


Steve
I agree, I can't help thinking it is a glitch in the electronics.
05-15-2019, 03:08 PM   #69
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QuoteOriginally posted by stevebrot Quote
Let's just leave them as is for now. Let me know if you send it off. It is a shame that you fall through the cracks as far as warranty service goes.


Steve
QuoteOriginally posted by SharkyCA Quote
I agree, I can't help thinking it is a glitch in the electronics.
Latest update on this K-70 problem.
Sent camera in 2 weeks ago and received back this estimate for repair "diaphragm block replacement" authorized repair and waiting for the return of my K-70.
Attached Images
 
05-15-2019, 03:45 PM   #70
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QuoteOriginally posted by SharkyCA Quote
Latest update on this K-70 problem.
Sent camera in 2 weeks ago and received back this estimate for repair "diaphragm block replacement" authorized repair and waiting for the return of my K-70.


Sorry to read that, but at least you know for sure. Is there any chance Ricoh Canada might cut you some slack under warranty?


Steve

Last edited by stevebrot; 05-15-2019 at 03:53 PM.
05-15-2019, 04:06 PM - 1 Like   #71
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QuoteOriginally posted by SharkyCA Quote
Latest update on this K-70 problem.
Sent camera in 2 weeks ago and received back this estimate for repair "diaphragm block replacement" authorized repair and waiting for the return of my K-70.
I hope this will be covered under warranty. Check with Ricoh. Also it would be nice if Sun could send you the old diaphragm control block. It would be interesting to compare it with the K-30/50 and K-S1/S2 block.
05-16-2019, 04:01 AM   #72
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QuoteOriginally posted by stevebrot Quote


Sorry to read that, but at least you know for sure. Is there any chance Ricoh Canada might cut you some slack under warranty?


Steve
QuoteOriginally posted by Not a Number Quote
I hope this will be covered under warranty. Check with Ricoh. Also it would be nice if Sun could send you the old diaphragm control block. It would be interesting to compare it with the K-30/50 and K-S1/S2 block.
Sent an inquiry to Ricoh Canada and also a request to Sun Camera Service to have the old part returned with the camera, thanks for the suggestions....fingers crossed!
06-06-2019, 02:31 PM   #73
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QuoteOriginally posted by stevebrot Quote
Intermittent problems are so hard to diagnose.

This thread is not really intended for extended troubleshooting. Although it is unclear whether you have an issue with aperture control*, you clearly have a problem and it is likely that service is your best option. If may be that more than one issue is at work here and the service center can evaluate in a short period of time what would require days of online discussion.


Steve

* My understanding is that you have not been able to observe inappropriate stop-down for any of mix of camera and lens (M mode, aperture wide open, aperture control function directly observed through front of lens)
QuoteOriginally posted by stevebrot Quote


Sorry to read that, but at least you know for sure. Is there any chance Ricoh Canada might cut you some slack under warranty?


Steve
Finally got my camera back from SunCamera Service, I have only taken 1 Photo but at least that worked.

Here is the part they replaced Diaphragm Control Block, I bought the camera Sept 2017, I notice the date stamp on the returned part is July 2017 ???
Attached Images
 
06-06-2019, 02:49 PM   #74
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Interesting, because the picture of the control block in a K-70 posted on the German Pentaxians forum has a different configuration. The infamous green solenoid is mounted diagonally. The block you show looks similar if not identical to the earlier assembly. I recall someone saying the K-70 block is not compatible with the K-S1/S2 and K-30/50.

Did Sun list a part number as well on the invoice/work order?

BTW: there appears to be two dates on it - 2017.7.14 and 2017.8.10. Assembly and inspection dates?
06-06-2019, 03:03 PM   #75
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QuoteOriginally posted by Not a Number Quote
Interesting, because the picture of the control block in a K-70 posted on the German Pentaxians forum has a different configuration. The infamous green solenoid is mounted diagonally. The block you show looks similar if not identical to the earlier assembly. I recall someone saying the K-70 block is not compatible with the K-S1/S2 and K-30/50.

Did Sun list a part number as well on the invoice/work order?

BTW: there appears to be two dates on it - 2017.7.14 and 2017.8.10. Assembly and inspection dates?
@Not A Number

Do you have a link for the German site??
No part # only description, not sure about date stamps.

I bought the camera in Sept 27 2017!!
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