My D600 sensor has three splotches visible at F32. They are quite large, maybe 3-5mm wide, and round. Now my understanding is that
small apertures produce highly collimated light, which creates well defined edges for dirt on the filter plate. Hence F32 highlights dirt. I
had never wet cleaned the sensor before I saw them. Two wet cleanings have not removed the splotches. Fortunately they do not appear
at F16, which is the aperture I use the most, but I do a lot of macro photography so it can be an issue.
So, does anyone know where the contaminant has come from? And what it is? The sensor does get a lot of dust in use, but I do use live
view a lot, especially with a microscope, so dirt ingress is to he expected. I dry cleaned the sensor, shot off 100 shots, and found no
increase in dirt, so I don't think this is the notorious D600 shutter gubbins issue. I can only think the marks were there from new.
