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04-06-2013, 12:04 PM   #1
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Opinion on sensor issue

Have been noticing that there were noticeable spots in images with clear areas such as sky. I contacted Pentax repair and subsequently sent the camera for inspection.

The reply below is what I am told. My question, how is it possible to get dust below the anti aliasing filter?

Any thoughts? Ray

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04-06-2013, 12:14 PM   #2
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Is it under warranty?
04-06-2013, 12:17 PM   #3
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What DSLR is this ...I had a K-7 that had dust underneath ... J
04-06-2013, 12:30 PM   #4
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Did you try cleaning it yourself before you sent it in? Like with a rocket blower or one of those sensor cleaning kits?

04-06-2013, 12:39 PM   #5
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First batch of K5 had this fabrication problem, they all got replaced or repaired under warranty.
04-06-2013, 12:45 PM   #6
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QuoteOriginally posted by Jean Poitiers Quote
What DSLR is this ...I had a K-7 that had dust underneath ... J
Sorry, forgot to mention that it is a K5. Yes, I looked at the sensor with a sensor scope, and wet cleaned it with Eclipse brand cleaning solution and sensor swab. I have done this before to my Nikons and this product always worked well. The camera is out of warranty. Actually it is the third K5, first one was replaced due to sensor stain, second one due to dead pixels, third time was the charm. Has been a great camera. Really carry it all the time. Just surprised at the repair reply. Can't comprehend how I could get dust between the sensor and filter. Rarely change lenses, always leave the 50-135 on it.
04-06-2013, 01:32 PM   #7
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QuoteOriginally posted by Ray Cox Quote
Can't comprehend how I could get dust between the sensor and filter. Rarely change lenses, always leave the 50-135 on it.
You can't but these fabrication faults gets worst over time i heard.
04-06-2013, 07:10 PM   #8
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My K5 was showing a dark spot on photos similar to your dark spot, same intensity/style and location. It started as a piece of gunk from I presume the mechanical workings of the K5. It was on the focus screen initially! Unfortunately I tried a blower to get rid of it and it landed on the sensor. Was I think quite sticky and could not be blown off the sensor. Still had my K5iis with me so no panic and put the long lens on the K5 as a temporary work around. On returning home I got a sensor cleaner: the sticky ball/pad type that you dab against the sensor. Pentax have their version : PENTAX O-ICK1 IMAGE SENSOR CLEANING KIT, although I used the Promaster version. Several dabs and this gunk was removed.
cheers
bb2

04-13-2013, 03:38 PM   #9
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My K5 is still remarkably clean. My K10D is another story. The spot healing tool is my friend.......

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04-14-2013, 08:03 AM   #10
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QuoteOriginally posted by Ray Cox Quote
Have been noticing that there were noticeable spots in images with clear areas such as sky. I contacted Pentax repair and subsequently sent the camera for inspection.

The reply below is what I am told. My question, how is it possible to get dust below the anti aliasing filter?

Any thoughts? Ray
This is written in general for the OP and IMO advice for anyone.

There are about 5 spots on the front of your K5 cover that holds the AA filter as well; but not under. Those are more blurry as they should be.

Saying you can't get dust under the AA filter goes against the instructions in Pentax PDF service manuals and against what really can happen, but very rarely. The manual for the techs have always said to not use a blower because of the potential to get dust under the AA filter. It proceeds to show the tech how to do a wet cleaning.

The AA filter cover is like a door with seals that fits over the sensor. Like any part its not guaranteed to always keep back dust/water. However its extremely rare for it to leak! I tell it like I see it with nothing to gain or lose, only the good feeling to help another person.

You state that you wet clean, do you ever blow air with a rocket blower? Did a little too much liquid get down around the sensors door or just on the sensor cover? I am thinking the latter may have happened. This let contaminates of microscopic size expose any weakness (that's not suppose to be there) and there is the result. It looks big but is probably very thin. That is a tiny amount of liquid leaked under and brought in some contaminate with it (contaminate washed in with cleaning solution) or air, one or the other had to happen. But its not your fault it leaked.

OK lets look at the facts. Fact your K5 having had the stains issue probably made you check each of your three K5s really good. Now all of a sudden there is debris under the AA filter (if Pentax is right). Fact most of Pentax service manuals tell the tech not to blow air with a bulb blower onto the sensor for the slight risk of blowing something under the AA filter. The tech should wet clean. Fact a bit too much wet cleaning fluid can expose any flaws in manufacture just as blowing.

Here is a page (shown below). This sensor is sealed just like the K5 sensor. This is a Pentax service manual. The T600 is the cover assembly. This is translated from Japan to English (by Pentax) so its wording is not always perfect. Like saying dust can enter the CCD. Well that would be really hard! It should read dust can get under the sensor cover which is the part (T600).

Take a look at the sensor sitting in the K5II body (K-5II / K-5IIs?PENTAX RICOH IMAGING). You will see a large cover with two screws on top and if you look careful two hinges on the bottom, like a door that swings open from top down. There are seals around the door and seals around the glass on top that protects and contains the SP layer, AA filter... So there are many potential areas for dust or liquid to enter. Now the sensor is free floating and on the sensor shake platter for cleaning on older models its shaken a lot. On the K7 and newer models its still oscillated a good bit for shake reduction. So the seals need to be good. They must be good, because its rare for anything to get under those covers from my readings and owner for years. Except for the stains issue and that could have happened anytime during manufacturing. I don't worry about it at all. But things happen sometimes - as in your case.

I have never used a blower on my sensor in years. I only use a special brush and wet cleaning when needed. And with the K5 that's never so far. But again if it does need it I won't use a blower. I do use a blower on the focus screen (bottom) if I see a sudden spot. This means a piece of something is stuck on the bottom. So I give a very gently puff of air and I mean like slow motion. If this does not do it I have a special brush for the focus screen that I clean top and bottom and the area above the focus screen. I also clean the mirror and chamber with special gear. I just like keeping as much dust and contaminates out of my dSLR bodies as I can.

If your going to use a blower do it per instructions. Don't put the tip into the body. The spray pattern will hit the top of the cover then out. So there is little pressure on any of the seals. But if that does not work, don't get in deeper or keep blowing harder and longer. You can make things worse in other areas. Its time for a wet clean. And when wet cleaning make sure not too much fluid is on the swab, you don't want to little that it dries up too soon, but not too much as well.

BTW because there are still spots (other than those big ones) on your sensor after you wet cleaned there is a chance something went wrong. I would buy another kit of any brand and try again. Those spots are not super sharp, they are large and blurry and could be on the outside!


Now I feel bad I can give all these warnings after the fact. Although I have written about this many times before you may not have seen it. But I don't know how you could clean the sensors cover without taking your K5 apart. Perhaps it won't cost much. A sincere good luck. Believe me I break my own rules to


Last edited by jamesm007; 04-14-2013 at 10:05 AM. Reason: BTW, clairity
04-15-2013, 11:38 AM   #11
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QuoteOriginally posted by jamesm007 Quote
This is written in general for the OP and IMO advice for anyone.

There are about 5 spots on the front of your K5 cover that holds the AA filter as well; but not under. Those are more blurry as they should be.

Saying you can't get dust under the AA filter goes against the instructions in Pentax PDF service manuals and against what really can happen, but very rarely. The manual for the techs have always said to not use a blower because of the potential to get dust under the AA filter. It proceeds to show the tech how to do a wet cleaning.

The AA filter cover is like a door with seals that fits over the sensor. Like any part its not guaranteed to always keep back dust/water. However its extremely rare for it to leak! I tell it like I see it with nothing to gain or lose, only the good feeling to help another person.

You state that you wet clean, do you ever blow air with a rocket blower? Did a little too much liquid get down around the sensors door or just on the sensor cover? I am thinking the latter may have happened. This let contaminates of microscopic size expose any weakness (that's not suppose to be there) and there is the result. It looks big but is probably very thin. That is a tiny amount of liquid leaked under and brought in some contaminate with it (contaminate washed in with cleaning solution) or air, one or the other had to happen. But its not your fault it leaked.

OK lets look at the facts. Fact your K5 having had the stains issue probably made you check each of your three K5s really good. Now all of a sudden there is debris under the AA filter (if Pentax is right). Fact most of Pentax service manuals tell the tech not to blow air with a bulb blower onto the sensor for the slight risk of blowing something under the AA filter. The tech should wet clean. Fact a bit too much wet cleaning fluid can expose any flaws in manufacture just as blowing.

Here is a page (shown below). This sensor is sealed just like the K5 sensor. This is a Pentax service manual. The T600 is the cover assembly. This is translated from Japan to English (by Pentax) so its wording is not always perfect. Like saying dust can enter the CCD. Well that would be really hard! It should read dust can get under the sensor cover which is the part (T600).

Take a look at the sensor sitting in the K5II body (K-5II / K-5IIs?PENTAX RICOH IMAGING). You will see a large cover with two screws on top and if you look careful two hinges on the bottom, like a door that swings open from top down. There are seals around the door and seals around the glass on top that protects and contains the SP layer, AA filter... So there are many potential areas for dust or liquid to enter. Now the sensor is free floating and on the sensor shake platter for cleaning on older models its shaken a lot. On the K7 and newer models its still oscillated a good bit for shake reduction. So the seals need to be good. They must be good, because its rare for anything to get under those covers from my readings and owner for years. Except for the stains issue and that could have happened anytime during manufacturing. I don't worry about it at all. But things happen sometimes - as in your case.

I have never used a blower on my sensor in years. I only use a special brush and wet cleaning when needed. And with the K5 that's never so far. But again if it does need it I won't use a blower. I do use a blower on the focus screen (bottom) if I see a sudden spot. This means a piece of something is stuck on the bottom. So I give a very gently puff of air and I mean like slow motion. If this does not do it I have a special brush for the focus screen that I clean top and bottom and the area above the focus screen. I also clean the mirror and chamber with special gear. I just like keeping as much dust and contaminates out of my dSLR bodies as I can.

If your going to use a blower do it per instructions. Don't put the tip into the body. The spray pattern will hit the top of the cover then out. So there is little pressure on any of the seals. But if that does not work, don't get in deeper or keep blowing harder and longer. You can make things worse in other areas. Its time for a wet clean. And when wet cleaning make sure not too much fluid is on the swab, you don't want to little that it dries up too soon, but not too much as well.

BTW because there are still spots (other than those big ones) on your sensor after you wet cleaned there is a chance something went wrong. I would buy another kit of any brand and try again. Those spots are not super sharp, they are large and blurry and could be on the outside!


Now I feel bad I can give all these warnings after the fact. Although I have written about this many times before you may not have seen it. But I don't know how you could clean the sensors cover without taking your K5 apart. Perhaps it won't cost much. A sincere good luck. Believe me I break my own rules to
Thanks for the reply. I must admit I am a little baffled that dust could be below the low pass filter. I am really anal about being careful when changing lenses. I have never used a blower of any type because I believe they can cause problems instead of getting rid of them.
Wet clean was done very carefully with "Sensor Swab" brand and "Eclipse" brand fluid. Tried twice, one pass in each direction. When results were no good, I sent the camera to Pentax repair. The reply was dust between the low pass filter and sensor. Replace sensor, $420. I declined. Not sure of the next move. Thanks, Ray
04-28-2013, 10:54 AM   #12
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Funny. What a timely thread! My k-5's sensor is now failing. Thankfully it is still under warranty for now. I pulled out my k-7 and cleaned it because I haven't used it in a while and the mirror box was pretty dusty when I put it away last. I had a piece of dust under the LPF and this cleaning just introduced a new piece of dust. I do blame the rocket blower forcing air under the filter. Its the only thing that makes sense to me, which means the seals on the AA filter are probably not so great ATM. :/

Its not worth replacing the sensor on my k-7, so I'm just going to live with the two dust spots while my k-5 goes in for warranty. I wish I would have known the tidbit about the rocket blower. I thought the AA filter seals were pretty decent. Guess not. I'm tempted to send it out to have the filter removed for IR conversion. That was my plan all along. I wonder why pentax replaces the whole sensor assembly when the filters can be changed for IR conversion. Why can't they just pull the filter, clean it and reseat it?
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