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02-24-2011, 01:06 AM   #1
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Stain Question

Another question about the stains, yes I know how to test for them and what they look like. But I have a question before I buy....
FWIW I will be testing the K-5 in store before purchase.

If I find a stain free K-5 after in store testing, will it remain stain free, or will/can these stains show up later on after the camera has been used for a while?

02-24-2011, 01:23 AM   #2
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Maybe Yes, Maybe No.

These were all done when my K5 was only a week old (to me). There are full stop down photos (f22 etc) in each set.

Index of /Photos/50mmShootout

The Stain didn't appear until Mid January. It's a crapshoot at this point as far as I'm concerned. If my replacement camera exhibits the stains within the warranty period again, they will replace (or repair) the camera, Again.

02-24-2011, 01:41 AM   #3
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Ok thanks Jeff, i guess its a gamble then.
Also will stains show up on photos at aperture's f/5.6 and bigger?
02-24-2011, 02:16 AM   #4
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Sony kenno on aina sony kenno.


02-24-2011, 02:36 AM   #5
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QuoteOriginally posted by 30v iPentax Quote
Sony kenno on aina sony kenno.
What does that have to do with my question?
02-24-2011, 06:57 AM   #6
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QuoteOriginally posted by TOUGEFC Quote
Ok thanks Jeff, i guess its a gamble then.
Also will stains show up on photos at aperture's f/5.6 and bigger?
Not in my experience. I imagine if I waited long enough they may have gotten worse and showed up but mine were discovered around the f16 range (k28mm f2.0). The theory is that they were there from the start but using Live View enough cooked them in. I tend to believe that theory because I know for a fact that the inside of my camera was never exposed to anything that would have caused this..



Just like everyone elses, pretty much dead center of the picture.

02-24-2011, 11:52 AM   #7
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QuoteOriginally posted by JeffJS Quote
Maybe Yes, Maybe No.

These were all done when my K5 was only a week old (to me). There are full stop down photos (f22 etc) in each set.

Index of /Photos/50mmShootout

The Stain didn't appear until Mid January. It's a crapshoot at this point as far as I'm concerned. If my replacement camera exhibits the stains within the warranty period again, they will replace (or repair) the camera, Again.

I don't understand.
These stains are on the bottom surface of the AA filter and got there because of some solvent issue producing the filters.
How can new stains get there after manufacturing?
I guess the new stains you are discovering are "normal" dust spots, a risk of changing lenses.
Or am I misunderstanding your reply?

- Bert
02-24-2011, 11:59 AM   #8
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QuoteOriginally posted by bymy141 Quote
I don't understand.
These stains are on the bottom surface of the AA filter and got there because of some solvent issue producing the filters.
How can new stains get there after manufacturing?
I guess the new stains you are discovering are "normal" dust spots, a risk of changing lenses.
Or am I misunderstanding your reply?

- Bert
I believe the current thought it that yes, the stains are between the AA filter and the sensor. However, based on the fact that the stains don't always appear right away and/or grow in number, intensity and size, there is a theory that while the solvent is present from the start, the heat the sensor generates during use can cause the stains to appear/enlarge/darken.

02-24-2011, 01:51 PM   #9
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QuoteOriginally posted by bymy141 Quote
I don't understand.
These stains are on the bottom surface of the AA filter and got there because of some solvent issue producing the filters.
How can new stains get there after manufacturing?
I guess the new stains you are discovering are "normal" dust spots, a risk of changing lenses.
Or am I misunderstanding your reply?

- Bert
I didn't say it wasn't there. I said it didn't appear in the photos right away. If it had Never appeared in the photos, I would not have gone a full month without my K5. Trust me, I know what dust looks like and the photo I show above has nothing to do with dust.

QuoteOriginally posted by dgaies Quote
I believe the current thought it that yes, the stains are between the AA filter and the sensor. However, based on the fact that the stains don't always appear right away and/or grow in number, intensity and size, there is a theory that while the solvent is present from the start, the heat the sensor generates during use can cause the stains to appear/enlarge/darken.
^^^^^^^

What he said.

02-24-2011, 01:55 PM   #10
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QuoteOriginally posted by dgaies Quote
there is a theory that while the solvent is present from the start, the heat the sensor generates during use can cause the stains to appear/enlarge/darken.
I doubt we'll ever get any explanations from Pentax, but up to now thats the theory I personally think is most likely.

Pat
02-24-2011, 09:18 PM   #11
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The one wo got stain was the early production . Whit the new production lately , nobody have complaint and I do not expect issue long term . Stay away from lower serial #
02-25-2011, 02:58 AM   #12
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If I'm not wrong you may not explore a stain when you test the brand new camera at dealer's place. Because some stains are becoming visible after using the camera for sometime, especially after making long exposure shots. At least like mine. It's said to be some parts of the layer on the sensor is burnt during long exposure depending on the increasing sensor heat and these seem as stains.
02-25-2011, 03:18 AM   #13
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QuoteOriginally posted by bobmaxja Quote
The one wo got stain was the early production . Whit the new production lately , nobody have complaint and I do not expect issue long term . Stay away from lower serial #
Perhaps I missed it, but from which serial number on is 'it' safe?
02-25-2011, 04:46 AM   #14
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The conjecture is that drops of solvent used in the manufacture trapped inside the sensor assembly eventually evaporate and leave behind a residue (=stain). This is based on the stament from Pentax Germany that was posted here; this mentioned "volatile material", assuming solvent from the manufacturing process is guesswork of course. This would explain how some units develop stains as that "volatile material" evaporates (because the sensor draws current and gets warm in use).
02-25-2011, 04:52 AM   #15
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QuoteOriginally posted by philippe Quote
Perhaps I missed it, but from which serial number on is 'it' safe?
Units made since week 50/2010 should be ok per Pentax Germany statement, the manufacture date can be found in the image files with PhotoMe or somesuch. (Apparenty the serial numbers do not correspond strictly to the manufacture date).
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