Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
10-03-2019, 03:25 PM   #1
Site Supporter
Site Supporter




Join Date: Jun 2013
Location: Washington DC
Photos: Albums
Posts: 526
Confirming troublesome stop down metering behavior

This thread explains someone else's discover a few years ago: Stop down metering only works in liveview on K-R with manual M lenses - PentaxForums.com

I can confirm this behaviour now on K-S2 with Aperture Block Failure. Stop down metering yields correct exposure ONLY in Live View. Stop down appears to operate out of LV, but the time value is incorrect. It corrects itself only in LV.


So this is TWO internal failure of my K-S2, as far as I can tell.

10-03-2019, 03:42 PM   #2
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 34,472
QuoteOriginally posted by Marktax Quote
This thread explains someone else's discover a few years ago: Stop down metering only works in liveview on K-R with manual M lenses - PentaxForums.com

I can confirm this behaviour now on K-S2 with Aperture Block Failure. Stop down metering yields correct exposure ONLY in Live View. Stop down appears to operate out of LV, but the time value is incorrect. It corrects itself only in LV.


So this is TWO internal failure of my K-S2, as far as I can tell.
This behavior is well-known and actually noted in the K-S2 camera manual (page 115), though without mention of a live view workaround. Inconsistent stop-down metering with the optical viewfinder has been a characteristic, to varying degrees, of all Pentax dSLRS since at least 2006 and is also an issue for dSLR cameras from other makers. The root cause is related to focus screens used with auto-focus cameras and meter behavior when the aperture is not known to the exposure system. Fortunately, it is not nearly as bad now as in the past.

This article may be helpful:
Stop-down metering, why it is a problem, and how to make it work - PentaxForums.com

Steve

Last edited by stevebrot; 10-03-2019 at 04:05 PM.
10-03-2019, 04:50 PM   #3
Site Supporter
Site Supporter




Join Date: Jun 2013
Location: Washington DC
Photos: Albums
Posts: 526
Original Poster
QuoteOriginally posted by stevebrot Quote
This behavior is well-known and actually noted in the K-S2 camera manual (page 115), though without mention of a live view workaround. Inconsistent stop-down metering with the optical viewfinder has been a characteristic, to varying degrees, of all Pentax dSLRS since at least 2006 and is also an issue for dSLR cameras from other makers. The root cause is related to focus screens used with auto-focus cameras and meter behavior when the aperture is not known to the exposure system. Fortunately, it is not nearly as bad now as in the past.

This article may be helpful:
Stop-down metering, why it is a problem, and how to make it work - PentaxForums.com
Steve
Thanks very much for that article. My fix will not be to carry a light meter, but simply to use LV. But obviously, this is a first-world problem which I am embarrassed to have raised at all. I can afford another camera and not try to fix this K-S2 at all. My point is that it is simply too bad that Pentax/Ricoh purchased those bad aperture blocks from China as a cost savings measure, putting a timebomb in a lot of cameras from K-30, K-50, K-S1, K-S2, and maybe K-70. Pentax/Ricoh should seek reparations from that Chinese supplier and pass that money on in REPAIRS to existing, sold cameras.
10-03-2019, 05:56 PM   #4
Moderator
Site Supporter
Loyal Site Supporter
Sandy Hancock's Avatar

Join Date: Feb 2012
Location: Adelaide Hills, South Australia
Photos: Gallery | Albums
Posts: 8,314
Moved to K-S1/K-S2 sub-forum.

10-09-2019, 03:09 AM   #5
Site Supporter
Site Supporter




Join Date: Apr 2015
Location: Winterthur
Photos: Albums
Posts: 627
QuoteOriginally posted by Marktax Quote
... My point is that it is simply too bad that Pentax/Ricoh purchased those bad aperture blocks from China as a cost savings measure, putting a timebomb in a lot of cameras from K-30, K-50, K-S1, K-S2, and maybe K-70. Pentax/Ricoh should seek reparations from that Chinese supplier and pass that money on in REPAIRS to existing, sold cameras.
Pentax/Ricoh did not buy those solenoids as cost-saving measures.

The manufacturer moved manufacture from Japan to China. Nothing that Ricoh could do.
But they tested those solenoids for many years in the flash-compartments of the K100D, K110D, K100D Super, K200D, Km/2000, Kx and Kr.
Nothing went wrong. About 6 years of perfect function.
So then they used it first in the K30.

I wrote all about it in detail here:
Relating to the changes in the K-70

as well as here:
in the complete history/development of the solenoid

and here:
were I wrote about what Pentax/Ricoh knew or better didn't know

Anyway, Shinmei, the manufacturer made it very clear by claiming:

The appearance and specifications of the products may be modified without prior notice to improve its performance
and:
Please confirm the performance on actual operation by simulation with actual enviroments for high reliability

So nothing that Ricoh could do, zero chance of seeking reparations!
10-09-2019, 07:28 AM   #6
Site Supporter
Site Supporter




Join Date: Jun 2013
Location: Washington DC
Photos: Albums
Posts: 526
Original Poster
Thanks, Photogem. I did not see your original descriptions of this solenoid's history, but I appreciate knowing it now. I guess it is simply an unfortunate mystery that the solenoid worked in the flashes, but something about its interface with the shutter or its location in the camera or something unknown caused failures in its operation. My K-S2 failed under 5,000 clicks. I have not attempted to open it to repair it in either of the two known methods, but I do have the newest 55-300 lens that does not depend on the solenoid, and I have three stellar IQ older Pentax lenses with aperture rings so I can do green button stop down shooting with those (but only in Live View -- through the optical viewfinder, green button stop down metering has now stopped working, perhaps an evolution of the problem; I think it worked for a while but has stopped).
10-09-2019, 08:01 AM   #7
Site Supporter
Site Supporter




Join Date: Apr 2015
Location: Winterthur
Photos: Albums
Posts: 627
QuoteOriginally posted by Marktax Quote
Thanks, Photogem. I did not see your original descriptions of this solenoid's history, but I appreciate knowing it now. I guess it is simply an unfortunate mystery that the solenoid worked in the flashes, but something about its interface with the shutter or its location in the camera or something unknown caused failures in its operation. My K-S2 failed under 5,000 clicks. I have not attempted to open it to repair it in either of the two known methods, but I do have the newest 55-300 lens that does not depend on the solenoid, and I have three stellar IQ older Pentax lenses with aperture rings so I can do green button stop down shooting with those (but only in Live View -- through the optical viewfinder, green button stop down metering has now stopped working, perhaps an evolution of the problem; I think it worked for a while but has stopped).
Next time I have a Pentax with failing solenoid and I disassembled it I shall check about Green Button Metering and what it might be about.
Anyway, repairing the K-S2 is pretty easy and worth it, the K-S2 is a very good camera, kind of a wolf in sheepskin
10-09-2019, 09:29 AM   #8
retired sw engineer
Loyal Site Supporter
reh321's Avatar

Join Date: Nov 2014
Location: South Bend, IN, USA
Photos: Gallery | Albums
Posts: 15,273
QuoteOriginally posted by photogem Quote
Next time I have a Pentax with failing solenoid and I disassembled it I shall check about Green Button Metering and what it might be about.
Aperture control from the body failed in my K-30 a year ago, but the "green button" metering still works on lenses that have an aperture ring to control aperture from the lens.

10-09-2019, 09:36 AM   #9
Site Supporter
Site Supporter




Join Date: Jun 2013
Location: Washington DC
Photos: Albums
Posts: 526
Original Poster
QuoteOriginally posted by photogem Quote
Next time I have a Pentax with failing solenoid and I disassembled it I shall check about Green Button Metering and what it might be about.
Anyway, repairing the K-S2 is pretty easy and worth it, the K-S2 is a very good camera, kind of a wolf in sheepskin
Another person has also reported ovf/green button stop down working for a while, then becoming possible in Live View only. It seems like a second stage failure that does not always occur.

Can you help me identify the number of screws to be removed from the K-S2? I'll give it a go if all I need is a 000 size phillips head. Does the top need to come off? I think I saw one video in which the top of a K 30 was still on the camera when someone was trying to get to the solenoid. Other videos I've seen pull off the bottom, top, and front. I have not seen a video repairing the K-S2.
10-09-2019, 01:04 PM   #10
Site Supporter
Site Supporter




Join Date: Apr 2015
Location: Winterthur
Photos: Albums
Posts: 627
Attached some photos showing the location of the screws. You don't need to unscrew this screw deep down in the battery compartment.

The top needs to be lifted but not taken off. Otherwise it "jams" the frontpart. So you start with the bottom, take the rubber eyepiece off, open the flash without battery inside (important! No need to discharge the flash condensor, it is well protected), then left side, right side.

When you have exchanged the solenoid (better not to sand/file the plunger, bad idea, can lead to further damage!) against the white Japan solenoid just be carefull that you align the AF-M switch the right way, i.e. inner part (last photo) downwards and outer part on AF! See my description of the K-S1 repair manual, it is similar. Or vice-versa: Inner switch upwards and outer part on M.
Attached Images
           
10-09-2019, 02:22 PM   #11
Site Supporter
Site Supporter




Join Date: Jun 2013
Location: Washington DC
Photos: Albums
Posts: 526
Original Poster
Thanks very much for the info and confidence. I'm undertaking it now! I'll report back when done.
10-09-2019, 02:34 PM   #12
Site Supporter
Site Supporter




Join Date: Apr 2015
Location: Winterthur
Photos: Albums
Posts: 627
Good luck! And yes, report back!
10-09-2019, 02:55 PM   #13
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 34,472
QuoteOriginally posted by Marktax Quote
Thanks very much for the info and confidence. I'm undertaking it now! I'll report back when done.
Use care. The screws are JIS cross-head and not Phillips head. Under torque from a Phillips driver, they driver may rise in the slot and strip the screw.* JIS screwdrivers are strongly recommended when working on Japanese cameras or lenses having cross-head screws.


Steve

* Stripped heads are a common sign of clumsy repair attempts on lenses and cameras. If I see them on a listing photo, it is an automatic no-buy from my perspective.
10-10-2019, 09:35 AM   #14
retired sw engineer
Loyal Site Supporter
reh321's Avatar

Join Date: Nov 2014
Location: South Bend, IN, USA
Photos: Gallery | Albums
Posts: 15,273
QuoteOriginally posted by Marktax Quote
Another person has also reported ovf/green button stop down working for a while, then becoming possible in Live View only. It seems like a second stage failure that does not always occur.

Can you help me identify the number of screws to be removed from the K-S2? I'll give it a go if all I need is a 000 size phillips head. Does the top need to come off? I think I saw one video in which the top of a K 30 was still on the camera when someone was trying to get to the solenoid. Other videos I've seen pull off the bottom, top, and front. I have not seen a video repairing the K-S2.
"Green Button" metering sometimes doesn't work with my K-30; instead of "fixing" it, I simply bracket around a guess, and then use "chimping" to come sufficiently close that I can 'go the last inch' using gimp .... I'm just not willing to take the chance of screwing up a working camera in the hopes of making a little better - but that may be just me.
10-10-2019, 10:22 AM - 1 Like   #15
Site Supporter
Site Supporter




Join Date: Jun 2013
Location: Washington DC
Photos: Albums
Posts: 526
Original Poster
QuoteOriginally posted by stevebrot Quote
Use care. The screws are JIS cross-head and not Phillips head. Under torque from a Phillips driver, they driver may rise in the slot and strip the screw.* JIS screwdrivers are strongly recommended when working on Japanese cameras or lenses having cross-head screws.


Steve

* Stripped heads are a common sign of clumsy repair attempts on lenses and cameras. If I see them on a listing photo, it is an automatic no-buy from my perspective.
Yes, Steve, I agree that you make a very good point here about JIS drivers. I was wary of stripping screws heads, but I managed with a #000 Phillips. Another thing I was careful of was that nearly all of the screws bed into plastic holes, and feeling proper torque before stripping the plastic threads is tricky.

---------- Post added 10-10-19 at 01:29 PM ----------

QuoteOriginally posted by photogem Quote
Good luck! And yes, report back!
Thank you for your encouragement, photogem! I did this successfully, but I used the filing technique (which I know you do not recommend) rather than a white replacement solenoid -- I have no soldering equipment with tips small enough to work in that tight area. In brief, the camera is restored to full functioning.

To save time here, please see this thread at DP Review, and my comments as "drummercam," where I have described this effort. I left a ground wire unattached (which I did not expect to find) for lack of the soldering equipment. I expect you can identify the purpose of the wire, because I can find no loss of function.

Last edited by Marktax; 10-10-2019 at 10:31 AM. Reason: left out a fellow user's name
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, driver, equipment, failure, heads, jis, k-s1, k-s2, lv, pentax help, phillips, photography, plastic, screws, troubleshooting, wire
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pets The troublesome kitten liaztraht Post Your Photos! 4 10-08-2018 12:19 PM
stop down metering K1000 M42 - so lost... kwinning Troubleshooting and Beginner Help 3 03-04-2018 09:29 AM
Spotmatic F stop down behavior thenewreligion Pentax Film SLR Discussion 5 09-23-2017 08:37 PM
Strange behavior K20D .. no DOF preview, no aperture stop down - but works ok on 'A' kayakfari Pentax DSLR Discussion 3 03-19-2017 10:23 AM
Down down down down... innershell Post Your Photos! 5 08-06-2009 05:45 PM



All times are GMT -7. The time now is 11:10 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top