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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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10-11-2018, 05:13 PM - 1 Like   #16
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QuoteOriginally posted by bladerunner6 Quote
Your credit card won’t cover it?
Haha! My wife already used it to cover everything else. If my credit card covers anything else it's gonna be a K1 Mark Il.


Last edited by CodyH; 10-11-2018 at 06:12 PM.
10-12-2018, 02:38 AM   #17
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QuoteOriginally posted by CodyH Quote
Haha! My wife already used it to cover everything else. If my credit card covers anything else it's gonna be a K1 Mark Il.
So you have a credit card with extended warranty protection but you didn’t use it?
10-12-2018, 07:09 AM   #18
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QuoteOriginally posted by bladerunner6 Quote
So you have a credit card with extended warranty protection but you didn’t use it?
...The word "cover" might have two different meanings here. On this side of the world it means sufficient available credit to "cover" a purchase. If one's card offers consumer protection, it might also mean a form of extended warranty, but not all cards offer that.


Steve
10-12-2018, 07:20 AM   #19
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QuoteOriginally posted by stevebrot Quote
...The word "cover" might have two different meanings here. On this side of the world it means sufficient available credit to "cover" a purchase. If one's card offers consumer protection, it might also mean a form of extended warranty, but not all cards offer that.


Steve
By most definitions Michigan and Tennessee are on the same side of the world👍

I’m any case my question is did he buy it with a credit card that has extended warranty protection?

10-12-2018, 06:19 PM   #20
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QuoteOriginally posted by bladerunner6 Quote
By most definitions Michigan and Tennessee are on the same side of the world👍

I’m any case my question is did he buy it with a credit card that has extended warranty protection?
I misunderstood. Was making a wife spends all my money joke. I believe I used PayPal to purchase but it pulled funds from a card that may offer something like that. Right now I'm counting on Pentax to step up and keep a new Pentax customer happy.
10-19-2018, 10:44 AM   #21
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I purchased my K-70 in July 2016 as a result of my K-500 failing due to the aperture control block issue. I needed my camera before it would be returned from repair so I went ahead and purchased the K-70, body to have a camera for my upcoming trip. About that time is when I stumbled on this site and learned that I was not alone with this issue.

I bought my wife a K-S1 in April 2017 since she had recently expressed an interest in photography but we both weren't crazy about its layout. This past spring I stumbled on an ebay seller who had a tremendous deal on various Pentax bodies and decided to buy a couple of K-S2s, one for her and one for myself as a backup to my K-70. So as a family we now own 5 Pentax bodies. I regularly take two bodies with me when I go shooting so I can swap to another lens quickly. I took my K-S2 with me to Spain last month where I shot over 1000 photos in five days.

I got an m42/K mount adapter and have accumulated a bunch of m42 Takumar prime lenses and use them on my K-500. I also got a 45 degree split focusing screen that I put in the K-500 to aid in that area. I think I am covered but am not real happy to hear about potential issues with possibly all my Pentax bodies. The two K-S2s I purchased both had very low shutter counts, one was 8, and the other was under 200 - virtually brand new.

I just uploaded a photo taken with my K-70 to get the shutter count. As you can see I am well out of warranty in the event of any failures.

Your photo's metadata indicates the following:
Camera PENTAX K-70
Shutter Count 10,361
Manufacture Date 2016:04:28
Lens Sigma 17-70mm F2.8-4 DC Macro HSM | C

We'll see what happens. At least now I am hopefully prepared for whatever happens down the road.
10-19-2018, 11:29 AM   #22
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QuoteOriginally posted by Bruzer Quote
I just uploaded a photo taken with my K-70 to get the shutter count. As you can see I am well out of warranty in the event of any failures.
Am I reading correctly that that you are not reporting problems with underexposure with your K-70? If so, I hope your K-S2s and K-70 continue to operate properly as expected.


Steve

10-19-2018, 06:42 PM   #23
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Update as of 10/19/18 is Pentax/Ricoh has not responded to Precision camera about covering my repairs. They are staying in contact with me but I am still uncertain of it the repairs will be covered.

I do intend on asking that the faulty parts be returned with the camera. Especially if I have to pay out of pocket. They may decline to return the defective parts if warranty pays for it.

Fingers still crossed....
10-19-2018, 09:10 PM   #24
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QuoteOriginally posted by stevebrot Quote
Am I reading correctly that that you are not reporting problems with underexposure with your K-70? If so, I hope your K-S2s and K-70 continue to operate properly as expected.


Steve
That is correct. I am not reporting any issues. More disappointment in that all the bodies we have (my wife and I) are or may be suspect to this issue.

Sorry for any confusion.
11-01-2018, 06:51 PM   #25
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I sure do miss my camera. Maybe I should buy a new one as a backup! Haha
11-01-2018, 07:06 PM   #26
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QuoteOriginally posted by Bruzer Quote
That is correct. I am not reporting any issues. More disappointment in that all the bodies we have (my wife and I) are or may be suspect to this issue.

Sorry for any confusion.
No evidence to say that they are at more risk than for any other possible failure. Just because a few folks have had what may be a Dark aperture problem does not mean that there is a problem model wide as was the case with the green solenoid K-30s and 50s. You are making a huge jump without data to support it if you think that you need to worry. relax, enjoy shooting your cameras and if you ever have issues, the smart folks (not me,) here will help you figure it out before you send off a camera for repairs.
12-09-2018, 09:29 AM - 4 Likes   #27
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*Update* Pentax has agreed to cover my repairs under warranty at no cost to me. I sent the camera in on October 1 and they approved the repairs last week. Now I am waiting on parts is the status I'm getting. I will share any your of a repair story or explanation that I receive. So far they have still only confirmed aperture failure.
12-11-2018, 09:37 AM   #28
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QuoteOriginally posted by CodyH Quote
*Update* Pentax has agreed to cover my repairs under warranty at no cost to me. I sent the camera in on October 1 and they approved the repairs last week. Now I am waiting on parts is the status I'm getting. I will share any your of a repair story or explanation that I receive. So far they have still only confirmed aperture failure.
That is cool that the repair is covered and bad that it took them two months to figure that out.


Steve
12-11-2018, 09:56 AM   #29
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So far a good outcome. It would be great if Precision will return to you the defective part. The part number/name itself might not be helpful since Pentax has been using the same part number/name for the solenoid style block since the 80s. The motor version used in the K-5, K-3 and K-1 has a different part number. If there is a third part number then we might be able to conclude the K-70 is using a new design control block.
01-06-2019, 08:30 PM   #30
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After losing my K-30 to the aperture control block problem (not verified since I decided not to repair, but 99.99% certain as to cause), I now find my K-70 is exhibiting symptoms of the same failure. The only modern lens I can use (on either camera, after updating K-30 to K-50 firmware) is my Pentax-DA 55-300 ED PLM WR lens, the one with electronic aperture. In fact, using this lens probably hid from me the early signs of the failure as I rarely use other lenses now, unless I'm in the bush with my 90 mm Tamron macro. I have a bunch of manual and early K lenses, but don't find the inclination to use them much of the time.


I have a two year no-questions asked third-party Australian warranty on the K-70 so hopefully that repair won't cost me, but my K-30 is now 4+ years out of warranty. The K-70 first exhibited problems 9 months after purchase, at about 8000 images, K-30 at about 5 years (and some 13,500 images).

So here's hoping that all is well, and I get a longer time before failure from the repair to the K-70. In the meantime, I think the 90mm Macro will sit on my still working *ist-DS, and the 55-300 will be on the K-30(-50)!

Peter
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