Originally posted by robgo2 This is certainly a possibility, which raises an interesting question: If everyone tested their other cameras in the same way as they are now testing their K-5s, how many would find similar artifacts? The answer might be surprisingly high. I am not saying that there is not a genuine "stain" problem with some K-5s, but the actual prevalence may be far less than we are led to believe by threads such as this one.
Rob
I already did and commented. IMHO, almost every camera has a few isolated such spots. Certainly, my K-7 does.
What is distinct to the K-5 is the
string of stains. Or cluster if there are parallel strings.
I highly recommend people seeing a few stains but no string of stains report "no". Otherwise, we'll never see a pattern in the serial numbers.
Originally posted by Couscousdelight It often looks like a splash on pics posted. Is is possible than it's a transparent liquid on the top of the sensor, or maybe between the AA & glasses layers. Could the liquid, be "cooked" by the heat of the sensor, then turn harsh and opaque ?
What looks like a splash, cell, bacteria or oil drop most likely is a solid obstruction of about dust particle size. I explained in Stainology why the image looks as it does.
Originally posted by dgaies It certainly appears that there are two distinct types of stains. 1) the long string of (typically) horizontal dots and 2) the single or small grouping of darker circles with a lighter outer ring (the ones that almost look like biological cells). I wonder if they are from the same contamination-source or if it's possible there were actually two different types of contamination.
The string is what is of interest here. Mine is 45 degrees.
The isolated ones is "normal" contamination probably seen in every second camera, if there only are very few and unclustered.
All stains have the dark center if the f-stop and particle are large enough to produce an umbra shadow. The lighter outer ring is penumbra shadow.