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05-21-2018, 12:45 PM   #16
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QuoteOriginally posted by stevebrot Quote
Sorry, I did not see your edit to the original post. Those look like the spots from the other posts and possible evidence of liquid infiltration at the edges. When you said delamination, I expected something like the material lifting from its substrate.

Good luck with Ricoh or with giving this delamination idea "wings".

By any chance have you or a previous owner ever wet-cleaned the sensor or main mirror?


Steve
The sensor was last wet-cleaned more than a year ago, and I have never cleaned the mirror with anything other than a blower bulb.

Liquid ingress seems possible, but that wouldn't really explain the spots in the middle of the AF sub-mirror, and the main mirror shows no evidence of similar contamination or damage.

Draco

---------- Post added 05-21-18 at 04:19 PM ----------

On my K-5, it looks like this:



Most of the spots in this case are dust, but notice the same discoloration around the edges.

Draco


Last edited by bwDraco; 05-21-2018 at 01:19 PM.
05-21-2018, 01:57 PM   #17
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QuoteOriginally posted by bwDraco Quote
The sensor was last wet-cleaned more than a year ago, and I have never cleaned the mirror with anything other than a blower bulb.
You had similar AF problems with your K-3II about a year ago. Do you think the two are related?


Steve
05-21-2018, 02:53 PM   #18
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Possibly. As far as I can tell, Precision only performed a CLA on the camera and its AF system; the AF sub-mirror may not have deteriorated to that point or they may not have recognized the true nature of the problem. The inconsistency reappeared a few months after the service.

Draco
05-21-2018, 07:26 PM   #19
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QuoteOriginally posted by stevebrot Quote
The main mirror is half-silvered and acts as a beam splitter with a portion of the light being reflected down to the PDAF sensor at the bottom of the mirror box by way of an auxiliary mirror angled down from the back of the main. This second mirror folds up and stows against the main mirror back with the mirror is in the "up" position, so we normally can't see it. The OP and others have been able to peek at this mirror by manually lifting the front edge of the main mirror a little.


Steve
Thanks for the hint, Steve !

05-22-2018, 06:02 AM   #20
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QuoteOriginally posted by bwDraco Quote
My Pentax K-3 II has been suffering from occasional focusing problems where the camera may lock focus far off target at times even in good light on a high-contrast subject. The error is typically front-focus but can sometimes be back-focus, and cannot be addressed by AF fine adjustment because of its inconsistent nature. The behavior also appears to be somewhat dependent on color temperature. All of my lenses are affected.

I tried cleaning the AF sensor with a blower bulb and while it appears to have improved, it did not completely address the problem. Should I try again, or send in the camera?

Has anyone else sent in their cameras to Precision for this issue, and did they address it effectively? If I'm to send mine in, should I send in the lenses as well? The camera is out of warranty, but that's not an issue for me.

Draco




It turns out the problem is delamination of the AF sub-mirror. How this is even possible is beyond me, but it looks like this will have to be sent to Precision.




Anyone else experienced this issue? Here's the note I'd send with the camera:


Draco
{edit} This may explain why my Focus Tune shots were so in consistent.

I've been noticing the same thing with inconsistent focus on a few of my lens using my K-3 recently. I just checked the sub-mirror and it has a few small spots (13 or 14), not nearly as severe as yours. My K-3 was made in Oct 2014 and I've never had a real problem with inconsistent focus before mid year 2017. I suspect the older the camera is and the more severe conditions it was used in the more this will become a problem.

Hopefully the K-3 replacement will get here before mine gets a lot worse.

Larry

Last edited by Larrymc; 05-22-2018 at 06:27 AM.
05-22-2018, 06:33 AM   #21
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On my K-3ii there are some spots that almost look like water spots, although this camera has never been wet cleaned to my knowledge.
On my K-30 there is what almost looks like dust on the secondary mirror. (its not dust, its inside the silvering itself) The K-30 i know for a fact has never been wet cleaned, or really even exposed to water for that matter.
05-22-2018, 09:31 AM   #22
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OK, my problem has been resolved. After reading the other posts regarding spots on the sub-mirror, I decided to give a gentle cleaning a try and it worked. My spots turned out to be tiny grains of solid residue, possibly pollen particles and they would not loosen with a rocket blower but did come off when I very gently loosened them up with a Q-tip. After the Q-tip loosening I used the rocket blower to clear everything in the mirror box of particles including the sensor. A/F seems very snappy now and locks in very quickly. The PLM 55-300 is super quick and my Sigma18-200 HSM is very responsive all of my screw drive lenses also now are very responsive too. So, all in all, I'm very happy with things and have learned something from it all.

Just a caution be careful if you try this with a Q-tip as there is adhesive on the underside of the main mirror frame that can snag a few strands of Q-tip cotton.

Larry

Last edited by Larrymc; 05-22-2018 at 09:31 AM. Reason: spelling correction
05-22-2018, 09:31 AM   #23
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For the record, my K-3 is early production (late 2013) and has never had mirror or sensor wet-cleaned. The secondary mirror is immaculate with no spots. I have never had a problem with sketchy AF except in dim light or when the intended point of focus gave the camera little to work with.


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05-22-2018, 11:23 AM   #24
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QuoteOriginally posted by stevebrot Quote
For the record, my K-3 is early production (late 2013) and has never had mirror or sensor wet-cleaned. The secondary mirror is immaculate with no spots. I have never had a problem with sketchy AF except in dim light or when the intended point of focus gave the camera little to work with.


Steve
Well aren't you the lucky guy....Grin I change lens quite often in the field and where we live there is an abundance of pine pollen early in spring. I too have never had my sensor wet-cleaned but I have had small particles collect on my sensor which the Rocket Blower easily took care of. I've also had particles get on my focus screen a couple of times. I also shoot with zooms a lot and that may cause some of my particle problems.

BTW, did you shine a bright light on the sub-mirror or just take a peek at it?

Larry
05-22-2018, 11:38 AM   #25
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Interesting.

Here is the state of the secondary mirror in my K-3 II. There appears to be a mottled or blotchy effect across the entire surface. I can't determine with certainty whether the issue is on the secondary mirror itself or a reflection of the primary mirror.

I have wondered on occasion whether the camera has been inconsistent in its autofocus, but generally my shots are in focus. I'll need to do some calibrated tests.

I also have an old Nikon D70S, which a friend gave to me. I just looked at its secondary mirror -- it looks very similar to the one pictured here.

- Craig
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Last edited by c.a.m; 05-22-2018 at 11:43 AM.
05-22-2018, 01:34 PM   #26
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QuoteOriginally posted by c.a.m Quote
Interesting.

Here is the state of the secondary mirror in my K-3 II. There appears to be a mottled or blotchy effect across the entire surface. I can't determine with certainty whether the issue is on the secondary mirror itself or a reflection of the primary mirror.

I have wondered on occasion whether the camera has been inconsistent in its autofocus, but generally my shots are in focus. I'll need to do some calibrated tests.

I also have an old Nikon D70S, which a friend gave to me. I just looked at its secondary mirror -- it looks very similar to the one pictured here.

- Craig
The blotchy stuff looks like its the way the light is entering but you do have a bunch of debris on the mirror.

Larry
05-22-2018, 02:34 PM - 1 Like   #27
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QuoteOriginally posted by Larrymc Quote
Well aren't you the lucky guy....Grin
Yes, I am fortunate that while we get tons of pollen, it is not as bad as pine forests in the South or in the Sierra Nevada where it blows off the trees in dense clouds of sticky yellow. The reason I posted the comment was not to state how fastidious I am, but rather to help head off the rumor that secondary mirror delamination is pervasive in K-3 series cameras. In fact, I am not sure that there is of evidence of any kind of layer separation (sorry bwDraco) based on the photos referenced in this thread. What I see in the photos is some sort of droplet contamination on the mirror face and (on the OP's) what looks like moisture seepage at the mirror edge. While both might be traceable to a layer separation, I don't find the evidence compelling to that end.

In all fairness, I too would be alarmed if my secondary mirror looked like the OP's or those in the other images, though my next question would be what might the face of the PDAF detector look like. I will be curious to see the outcome of the service diagnosis and whether Ricoh will respond.


Steve
05-22-2018, 06:05 PM   #28
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I looked at my K5 and saw the spots as pictured. I gently cleaned it with a wet sensor cleaning swap, and the spots are gone! I used the plastic handle of another swap to gently lift the mirror. Dirt, Dust?
05-22-2018, 06:58 PM   #29
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QuoteOriginally posted by stevebrot Quote
Yes, I am fortunate that while we get tons of pollen, it is not as bad as pine forests in the South or in the Sierra Nevada where it blows off the trees in dense clouds of sticky yellow. The reason I posted the comment was not to state how fastidious I am, but rather to help head off the rumor that secondary mirror delamination is pervasive in K-3 series cameras. In fact, I am not sure that there is of evidence of any kind of layer separation (sorry bwDraco) based on the photos referenced in this thread. What I see in the photos is some sort of droplet contamination on the mirror face and (on the OP's) what looks like moisture seepage at the mirror edge. While both might be traceable to a layer separation, I don't find the evidence compelling to that end.

In all fairness, I too would be alarmed if my secondary mirror looked like the OP's or those in the other images, though my next question would be what might the face of the PDAF detector look like. I will be curious to see the outcome of the service diagnosis and whether Ricoh will respond.


Steve
Just a friendly "jab" on my part, Steve. I'm with you about the layer separation theory, I see what I see in many mirrors, moisture damage along the edges. I assume that the mirrors use some exotic coating as surface coating and I've never seen any mirror with the sort of deterioration being referenced as layer separation, contamination maybe but not layer separation but I'm not at all familiar with optical mirrors either

My mirror had a good many particles of debris that were only dislodged by very gentle coaxing with a Q-tip and thorough use of a Rocket Blower. The PDAF lens I cleaned several weeks back along with the sensor so they were pretty debris free.

Have you looked at your PDAF lens?

Larry
05-22-2018, 07:35 PM   #30
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Now this is interesting. I put a cotton swab on it and the spots disappear. However, merely putting pressure on the mirror is enough to remove the spot, and I see no indication of streaking when I gently wipe it.

Hence, this does not rule out delamination as pressure can cause sub-surface bubbles to disappear, but it does suggest it could just be oil or other contamination.

Autofocus consistency has improved dramatically since this operation. I'll be monitoring this closely to see if this issue reappears.

Draco

Last edited by bwDraco; 05-22-2018 at 08:03 PM.
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