Clue....I have been buying used lenses from thrift shops and other sources.
Recently I noticed spots on images that could only be dust on the sensor.
Multiple dust removals and then sensor cleaning worked for a while but the problem came back.
Long story short traced it to the flocking inside the smc Macro M100/f4.
Tried toothbrushing it out but after I had covered an A4 sheet of paper and still going I simply unscrewed the insert and stop-down actuator and removed it !!!
Now using the (cleaned) lens as complete manual and images seem ok.
Any tips or pointers to remove the flock from the insert ?? and what to replace it with...??
http://www.dpreview.com/forums/thread/2549384 Quote: Re: Pentax 100mm macro lens questions
In reply to Rod Herdman, Mar 20, 2009
Anyone interested in the 100 f4 M lens should also know that it has a flocked surface inside the rear of the lens to prevent internal reflections. No problem with film, but if any of that fuzz is loose it could be easily be drawn to your statically charged digital sensor.
Last edited by bobD; 03-04-2014 at 10:21 PM.