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03-04-2014, 10:14 PM   #1
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Dust in smc Macro M100/f4

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
QuoteQuote:
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.
03-04-2014, 10:34 PM   #2
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QuoteOriginally posted by bobD Quote
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...??

Pentax 100mm macro lens questions: Pentax SLR Talk Forum: Digital Photography Review
I've got a few old lenses with flocking that's falling apart and threatening to find its way to my sensors.
I thought about removing it and replacing it with really flat-black paint instead, or new black fabric material
But instead I used some miniature vacuum cleaner tools I had and was able use a little brush tool which loosened and vacuumed away all the loose material and it's sufficed for now.
03-04-2014, 10:56 PM   #3
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QuoteQuote:
for now.
That is what I thought but I am looking for a longer term solution.
Paint, black card, rubberised paint ????
Open to suggestions
03-04-2014, 11:04 PM   #4
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Tried micro-tools? I've bought flocking, amongst many camera and lens repair material from them a long time ago.
This was not what I bought but it may work.

Light Trap Material/Flocking 220mmx250mm

03-05-2014, 01:22 AM   #5
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Thanks, I am after an alternative to flocking. Something that won't detach and migrate to my sensor.
I am sure that the flock was a good idea back in film days but no way will I use a flocked lens again.

I need to know
a) what solvent will safely remove the existing flock and it's adhesive ?
and b) What contiguous material would best replace the flock ?

So far I have thought to use black card, some rubberised paint (for its textured effect) or just plain matte black...
03-05-2014, 07:29 AM - 1 Like   #6
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Acetone will remove the glue. You can get it in the finger nail polish area of most discount stores.
You can use a flat black model paint on the tube. Just as it gets tacky, run the brush around the tube to create rough rings to break up any light reflections from the surface.
Flat paint is still surprisingly reflective if not roughed up in some way.
I build telescopes and large camera lenses so have seen it all.
03-05-2014, 11:00 AM   #7
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Thanks wildlifephotog !! That is just what I needed to know.
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