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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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06-11-2019, 06:23 AM   #91
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QuoteOriginally posted by SharkyCA Quote
I do not see how these posts are "off topic" as it is documentation of "K-70 Diaphragm Control Failure" and the resolve to that failure, suggesting to open a new thread while this thread is already under "Pentax K-70, K-70 UnderexposedPhoto Reports" seems counter productive if we are looking for solutions.

I have to agree with Photogem.
I believe your photo reveals that we know less than we thought we did. The original purpose of this thread was to determine whether the K-70 really is failing less often than the K-50 did; the K-70 was released nearly three years ago, so the shortage of complaints would suggest something has changed, but your photo makes us less certain what that change might be. That is not bad, but it is somewhat disconcerting.

06-11-2019, 08:08 AM   #92
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QuoteOriginally posted by photogem Quote
It is by no means off-topic!
Read the original post. This thread is for reportage, not discussion, of what is turning out to be a rare problem. I know that the aperture control issue is a strong interest of yours and that participation in all related threads makes sense, but starting a side discussion is not helpful, IMHO.

QuoteOriginally posted by SharkyCA Quote
suggesting to open a new thread while this thread is already under "Pentax K-70, K-70 UnderexposedPhoto Reports" seems counter productive if we are looking for solutions.
We are looking to see if there is under-reportage of what is turning out to be a rare problem for K-70 owners. The solution is to get it repaired. So far yours is the only documented case of actual failure of the diaphragm control block on this site. Endless discussions of what component of the replaced unit might have failed are sort of futile. (I.e. there is no indication that the solenoid was at fault.) If you are planning on dissection or doing a powered test of the failed unit, that would be cool, but ultimately a new thread might result in better exposure. Yes, you have new "photographic evidence" for a problem that might be affecting other K-70 users, I am just making a suggestion to take the discussion elsewhere so that legitimate reports don't get lost in the melee and what you have found can get the attention it deserves. Now y'all (@photogem included) may do as you please. I don't own the thread, nor am I a moderator. I'm just the guy who interacts with those reporting dark frames.


Steve

Last edited by stevebrot; 06-11-2019 at 08:38 AM.
06-11-2019, 08:45 AM   #93
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QuoteOriginally posted by stevebrot Quote
Read the original post. This thread is for reportage, not discussion.
You opened a thread and you have a wish! A wish that everybody complies 100% to rules you want to dictate.
But this is an open forum and you are the TO, i.e. Thread* Opener. So that's what it is ... an open threat.

So please don't mix it up with a *"threat" instead.

QuoteOriginally posted by stevebrot Quote
The solution is to get it repaired.
This is "one solution". A good one, no daubt.


But .... we know too well that many repairs by Ricoh/Pentax have just led to the same failure again.

So actually, your solution is kind of limited.

Yes, to get it repaired is a good solution: If it is done well!


But... an even better solution would be if this very mistake wouldn't happen at all! There is nothing wrong with this approach.

Now: We had this problem since the days of the Pentax K30. It wasn't solved with the K50/K500. It wasn't fully solved but bettered with the K-S1 and K-S2.
And it still happens. To find out why it happens that is "my solution", you might not like it (you responses at least give me a strong indication that this is the case)
but remember please: This is a forum! You opened a thread. So please be open.

QuoteOriginally posted by stevebrot Quote
So far your's is the only documented case of actual failure of the diaphragm control block on this site.
No, it is at least the second documented case:
a) K-70 of SharkyCA
b) same unit installed offically into a K30


There several K70 documented cases on the German Pentaxians website!

I know at least of 4 of 'em.


QuoteOriginally posted by stevebrot Quote
Endless discussions of what component of the replaced unit might have failed are sort of futile.
For you this might be futile, but not for others.


QuoteOriginally posted by stevebrot Quote
I.e. there is no indication that the solenoid was at fault.
Well: How many Pentax DSLR with failed diaphragm control block have *you* checked, repaired?
You know that I have repaired many.


I can tell that "most likely" it was the solenoi who was at fault. With all 4 cases on the German Pentaxian forum it was so!


QuoteOriginally posted by stevebrot Quote
Yes, what came out of your camera is similar to a stock photo from U.S. Camera for the Pentax replacement part that they sell for an earlier model. What would one expect? The part numbers are very likely the same. The reversal of the screw holes might indicate a different mount plate underneath, but even if, is that revelation actionable?
to you, no, to me: YES! And I will prove why!


QuoteOriginally posted by stevebrot Quote
Yes, you have new "evidence" for a problem that might be affecting other K-70 users, I am just making a suggestion to take the discussion elsewhere so that legitimate reports don't get lost in the melee.
So you agree that there "might be new evidence" but at the same time you question my report being "legiti-mate" ???

---------- Post added 06-11-19 at 08:47 AM ----------

QuoteOriginally posted by reh321 Quote
I believe your photo reveals that we know less than we thought we did. The original purpose of this thread was to determine whether the K-70 really is failing less often than the K-50 did; the K-70 was released nearly three years ago, so the shortage of complaints would suggest something has changed, but your photo makes us less certain what that change might be. That is not bad, but it is somewhat disconcerting.
And that's exactly what I am after (and I am pretty sure I am on the right track!): What that change might have been!
06-11-2019, 10:32 AM   #94
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I am not trying to muddy the waters on this thread but perhaps it will be the solution for many K-70 owners and a resolve from Pentax so they don't duplicate the problem in the future.
Here are the macro pictures of the "solenoid" that came from my K-70 sent back to me from "SunCamera Service in Canada the authorized Pentax repair facility. Unfortunately not under warranty,.

The full control block image is here:

Attached Images
   
06-11-2019, 11:01 AM - 2 Likes   #95
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QuoteOriginally posted by photogem Quote
You opened a thread and you have a wish! A wish that everybody complies 100% to rules you want to dictate.
But this is an open forum and you are the TO, i.e. Thread* Opener. So that's what it is ... an open threat.

So please don't mix it up with a *"threat" instead.
Ummmmm...no, not really. OP's insistence on thread ownership is actually a pet peeve of mine. If you want to have a private party here, it is your privilege. I was just suggesting that to do so is off topic and might actually get better exposure as a new thread. If there is a desire to take it to the personal level (threats), I have little interest.

As for whether I have any experience with the aperture control issues...yes, first hand with a K-50 and yes, as one of those who handled the original surge of K-30 failures (almost all out of warranty by only a month or so) and one of those who characterized the issue as age rather than usage related. No, I have never taken one apart. The K-50 was repaired at Precision under warranty (thank you Ricoh for the extension) in early 2015 and continues to operate trouble-free to the present date. I have no idea what color solenoid was on the repair part, only that the repair was successful. In fact, I have no idea whether the solenoid was a fault, only that they replaced the diaphragm control block.

Having established that I don't do my own dSLR repair (I save that for vintage cameras and lenses), I do recognize your contribution, including the self-repair guide on this site. I am sure it has saved those attempting self-repair a world of pain. Given your post history on this site, the aperture control issue, particularly the solenoid part appears to be a matter of intense interest. I hope for you the greatest of luck in finding the truth regarding this type of failure. There have been so many blind leads and so many potential points of failure.


Steve

Last edited by stevebrot; 06-11-2019 at 11:07 AM.
06-14-2019, 09:10 AM   #96
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QuoteOriginally posted by stevebrot Quote
Read the original post. This thread is for reportage, not discussion, of what is turning out to be a rare problem. I know that the aperture control issue is a strong interest of yours and that participation in all related threads makes sense, but starting a side discussion is not helpful, IMHO.



We are looking to see if there is under-reportage of what is turning out to be a rare problem for K-70 owners. The solution is to get it repaired. So far yours is the only documented case of actual failure of the diaphragm control block on this site. Endless discussions of what component of the replaced unit might have failed are sort of futile. (I.e. there is no indication that the solenoid was at fault.) If you are planning on dissection or doing a powered test of the failed unit, that would be cool, but ultimately a new thread might result in better exposure. Yes, you have new "photographic evidence" for a problem that might be affecting other K-70 users, I am just making a suggestion to take the discussion elsewhere so that legitimate reports don't get lost in the melee and what you have found can get the attention it deserves. Now y'all (@photogem included) may do as you please. I don't own the thread, nor am I a moderator. I'm just the guy who interacts with those reporting dark frames.


Steve
QuoteOriginally posted by SharkyCA Quote
I am not trying to muddy the waters on this thread but perhaps it will be the solution for many K-70 owners and a resolve from Pentax so they don't duplicate the problem in the future.
Here are the macro pictures of the "solenoid" that came from my K-70 sent back to me from "SunCamera Service in Canada the authorized Pentax repair facility. Unfortunately not under warranty,.

The full control block image is here:
QuoteOriginally posted by stevebrot Quote
Ummmmm...no, not really. OP's insistence on thread ownership is actually a pet peeve of mine. If you want to have a private party here, it is your privilege. I was just suggesting that to do so is off topic and might actually get better exposure as a new thread. If there is a desire to take it to the personal level (threats), I have little interest.

As for whether I have any experience with the aperture control issues...yes, first hand with a K-50 and yes, as one of those who handled the original surge of K-30 failures (almost all out of warranty by only a month or so) and one of those who characterized the issue as age rather than usage related. No, I have never taken one apart. The K-50 was repaired at Precision under warranty (thank you Ricoh for the extension) in early 2015 and continues to operate trouble-free to the present date. I have no idea what color solenoid was on the repair part, only that the repair was successful. In fact, I have no idea whether the solenoid was a fault, only that they replaced the diaphragm control block.

Having established that I don't do my own dSLR repair (I save that for vintage cameras and lenses), I do recognize your contribution, including the self-repair guide on this site. I am sure it has saved those attempting self-repair a world of pain. Given your post history on this site, the aperture control issue, particularly the solenoid part appears to be a matter of intense interest. I hope for you the greatest of luck in finding the truth regarding this type of failure. There have been so many blind leads and so many potential points of failure.


Steve
Sorry Steve but I have to refer back to my original post on another thread and refer you back to your "original comment to me" K70 aperture block? - Page 3 - PentaxForums.com

Your Quote directing me back to this thread.
"There is a thread on this site dedicated to the matter including how to confirm that your camera has an aperture control problem. You are welcome to participate posting as is appropriate there, particularly in regards to whether you are able to to confirm an aperture control problem as well as any repair center diagnoses and final outcomes. Example photos are not needed, since they are a symptom that contains few, if any clues.*" https://www.pentaxforums.com/forums/193-pentax-k-70/377096-k-70-underexposed-photo-reports.html

Read more at: K70 aperture block? - Page 3 - PentaxForums.com

Last edited by SharkyCA; 06-14-2019 at 09:12 AM. Reason: add a link and update message.
06-14-2019, 11:27 AM   #97
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QuoteOriginally posted by SharkyCA Quote
Your Quote directing me back to this thread.
"There is a thread on this site dedicated to the matter including how to confirm that your camera has an aperture control problem. You are welcome to participate posting as is appropriate there, particularly in regards to whether you are able to to confirm an aperture control problem as well as any repair center diagnoses and final outcomes. Example photos are not needed, since they are a symptom that contains few, if any clues.*"
Yep...and that is still the case. Your problem was confirmed by Sun and repaired and unless the fix did not work, that is the final outcome.


Steve
06-14-2019, 05:28 PM   #98
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QuoteOriginally posted by stevebrot Quote
Yep...and that is still the case. Your problem was confirmed by Sun and repaired and unless the fix did not work, that is the final outcome.


Steve
So are you saying "end of discussion" the camera failed, was fixed and we don't care that it is going to happen again? Or are we looking for Ricoh/Pentax to step to the plate and rectify the problem instead of letting it continue into the next generations of DSLR?

Cheers

06-15-2019, 01:46 AM - 1 Like   #99
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Stevebrot is still looking for more confirmation of K-70 aperture block failures if you suspect your K-70 has failed like mine post it quoting his original post at the top of this thread.K-70 Underexposed Photo Reports - PentaxForums.com
06-16-2019, 05:12 AM - 2 Likes   #100
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So to keep the solenoid question apart from Stevebrot's thread which he wishes for reportage only I have started a new thread and uploaded photos which kindly SharkyCA sent me
and allowed me to use plus photos I took today from different solenoids to show how Ricoh did work to solve this problem (and they did!).

You find the new thread HERE

I think Ricoh did their best and I could document steps which also show why earlier approaches where not yet perfect and particular why the socalled sanding/grinding method is
a kind of foolish.

Ah... when I took the photo of the Japan-Solenoid the plunger which just came out of its housing, so was just fresh in contact with the magnet there:


A tiny metallic (ferro-magnetic) particle stuck to the front which was closest to the magnet!
06-20-2019, 08:03 AM - 1 Like   #101
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I also thought I had “Aperture Block” failure on my K-70 as I did on my K-30. But, I notice a symptom that was different and strange. If I used Live View in the Auto mode, the brightness would fade in and out and never stabilize. When I switched to Program mode, the brightness was as expected and stayed stable. I seemed like a software problem more than hardware. Reloaded firmware and everything seems to be working as expected, at least for now.
06-20-2019, 09:10 AM   #102
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QuoteOriginally posted by Burd Quote
I also thought I had “Aperture Block” failure on my K-70 as I did on my K-30. But, I notice a symptom that was different and strange. If I used Live View in the Auto mode, the brightness would fade in and out and never stabilize. When I switched to Program mode, the brightness was as expected and stayed stable. I seemed like a software problem more than hardware. Reloaded firmware and everything seems to be working as expected, at least for now.
Welcome to the Pentax Forums!

Sounds good. Post here again if you start having exposure problems similar to what you experienced with your K-30.


Steve
08-22-2019, 05:56 PM   #103
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I thought my dad also had the aperture block problem on his K70, but reading Burt's post makes me wonder. I did the test to see if we have the symptom he describes and it does appear that the live mode is super dark also and never comes in properly. Will update with firmware reset results.
08-22-2019, 06:55 PM   #104
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QuoteOriginally posted by tanz Quote
I thought my dad also had the aperture block problem on his K70, but reading Burt's post makes me wonder. I did the test to see if we have the symptom he describes and it does appear that the live mode is super dark also and never comes in properly. Will update with firmware reset results.
Welcome to the Pentax Forums. Post back here if you continue having problems with dark frames and if they appear to be due to aperture control problems.

In regards to Live Mode:
  • One can expect dark frames from photos taken in live view the same as from when using the optical viewfinder. Stopping down the lens is part of the exposure sequence for both modes.
  • One might also expect problems with the brightness of the view as well due to a feature of live view where the lens is stopped down slightly under bright conditions. Instead of a slight narrowing, the aperture may close down almost entirely, resulting in an abrupt temporary darkening. This behavior is poorly characterized and not diagnostic.
  • Optical depth of field preview is another feature that may suffer from a lapse of aperture control. Again, the stop-down is often to a much narrower aperture than that set on the camera.

I hope your problems are solved by the firmware fix.


Steve
08-23-2019, 01:53 AM   #105
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QuoteOriginally posted by stevebrot Quote
One can expect dark frames from photos taken in live view the same as from when using the optical viewfinder.
No, this is not at all the case:

1. I have had bodys with stuck solenoid, photos with LV (Live View) were alright, photos OV (optical viewfinder) dark as dark can be
2. I have a K30 here, photos with OV dark as dark can be, LV underexposed but not dark (see photos)
3. I had bodys were LV worked for a while but then after a while sitation 2 or 1

The solenoid acts twice when used in LV!


Photo 1, wide open, OV:


Photo 2, same photo as photo 1 wide open but modified to show the object


Photo 3, wide open, LV:


It is still underexposed but not as bad as photo 1.

As said, I had situations with darkframe via OV but perfect photos via LV.

Here a photo with repaired K30 (obligatory white "made in Japan" solenoid) OV wide open:


and the same object, wide open but LV:
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