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09-27-2016, 05:46 PM   #1
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pentax mirror spots

Hope this is the appropriate area for this post.

As of late I have been having more difficulty getting focus lock. Normally this would be when I clean out the mirror box with a rocket blower and remove any long strands, which somehow get in.
Normally I don't have a lot of bright light to work with but this time my room mate held an LED flashlight for me and that's when as I was lifting the mirror to clean the area I noticed the 2nd little mirror hinged to the bottom of the larger one.
It folds against the main mirror as it is lifted which is why I missed it all this time.
I was able to position it so I could see it and noticed maybe a dozen spots on the mirror. They didn't blow or brush off, They almost looked like oil splatters. I took a dry Qtip and cleaned the mirror and it cleaned up nicely. I was pretty sure the spots were not from condensation, common in Florida going from AC to heat simply because there were no signs of water spotting anywhere else. After cleaning that little mirror i was able to get focus lock 8 out of 10 times in a non light room easily whereas before it was more like 2-3 out of 10. Checking with 2 friends in the area with Pentax cameras, a K30 and a K3 they both found the same spots on the little AF mirror inside their cameras.
Does anyone know what causes this ? is there a fix ?
curious
.
Dewolf

09-27-2016, 07:00 PM   #2
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Conventional wisdom is to avoid touching the main mirror (very easy to scratch) and even more the secondary mirror that serves the PDAF sensor.

If you have oil on either mirror, I can assure you that it is not supposed to be there. The fix is to send it in to be cleaned and to find the source of the oil.

FWIW, I can also assure you that my K-3 does not have spots on either mirror and neither did the K10D that it replaced.


Steve
09-27-2016, 07:17 PM   #3
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QuoteOriginally posted by stevebrot Quote
Conventional wisdom is to avoid touching the main mirror (very easy to scratch) and even more the secondary mirror that serves the PDAF sensor.

If you have oil on either mirror, I can assure you that it is not supposed to be there. The fix is to send it in to be cleaned and to find the source of the oil.

FWIW, I can also assure you that my K-3 does not have spots on either mirror and neither did the K10D that it replaced.


Steve
normally yes I would have sent it in, but I did have conversation with Pentax and they hadn't a clue what it might be. I still have to wonder if going from an air conditioned home to 92 degrees with 98% humidity had something to do with it. It cleaned off well with the swab alone with a few wipes. just off my locals also have it and only on that mirror, but then none of them nor myself knew about that mirror, hence it wouldn't have ever been cleaned from day one. Im not advocating anyone to clean that but curiosity did get the best of me. If it shows up again I will send it to Precision and see what they think. Anyways after 3 weeks of other life, camera and I are going out in the morning to see what we can see
09-28-2016, 03:21 AM   #4
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QuoteOriginally posted by dewolf Quote
It cleaned off well with the swab alone with a few wipes. just off my locals also have it and only on that mirror, but then none of them nor myself knew about that mirror, hence it wouldn't have ever been cleaned from day one. Im not advocating anyone to clean that but curiosity did get the best of me. If it shows up again I will send it to Precision and see what they think.
Sorry about being curt in my previous comment. Were these spots on your K-5IIs? Like you, I wonder if they may be the result of condensation, perhaps around pollen grains. Did your AF improve as a result of the cleaning? FWIW, the AF detector itself may also have dust on its optics. That detector is recessed into the floor of the mirror box and faces up toward the secondary mirror you recently discovered. Normally, I would not suggest fiddling with cleaning those parts, but if they accumulate dust, AF performance will be effected.

To put your mind at ease about the oily appearance of the stuff on the mirror and the fact that you and your friends found it on a K-30 and a K-3, you might ask a Nikon or Canon shooter friend to look at the same part on their camera. All AF dSLRs have similar mirror setups and if such deposits are one of the side-effects of working in the near tropics, then similar stuff may be on those cameras as well.


Steve

09-28-2016, 04:25 AM   #5
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QuoteOriginally posted by stevebrot Quote
Sorry about being curt in my previous comment. Were these spots on your K-5IIs? Like you, I wonder if they may be the result of condensation, perhaps around pollen grains. Did your AF improve as a result of the cleaning? FWIW, the AF detector itself may also have dust on its optics. That detector is recessed into the floor of the mirror box and faces up toward the secondary mirror you recently discovered. Normally, I would not suggest fiddling with cleaning those parts, but if they accumulate dust, AF performance will be effected.

To put your mind at ease about the oily appearance of the stuff on the mirror and the fact that you and your friends found it on a K-30 and a K-3, you might ask a Nikon or Canon shooter friend to look at the same part on their camera. All AF dSLRs have similar mirror setups and if such deposits are one of the side-effects of working in the near tropics, then similar stuff may be on those cameras as well.


Steve
In doing some research I found that at one time the Canon 6D had an issue with oil from the mechanism getting onto mirrors. But this wiped off so easily that I think you hit it on the head with pollen. I have asked one of my friends to try and photograph the spots on his K30 as he has 2 cameras but he had already cleaned them off. Yes near tropics is what we have here, I do have to leave the camera in the car over night this time of year to acclimate so the lenses don't fog for morning shoots. and even then sometimes they'll fog from venue to venue lol.I spent decades repairing circuit boards, so being careful around small items was something i was used to, however with the advent of Parkinson's < mild > it is not quite as easy lol. But now that I know about this 2nd mirror I will make sure it gets a look at when I clean. As for the detector lens < cover> there was a long fiber strand near it. I used tweezers to get it out. considering a mini vacuum if they are worth it. I assume the suction affect of a zoom lens can cause this but now days I use the F4/300 prime and imagine it does not have as great a suction affect.
Thanks for your input, especially for the pollen idea, I really think that's the culprit. and yes, improved AF lock after cleaning
Dewolf
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