Originally posted by Ray Cox 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