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11-14-2017, 09:37 AM   #1
cyberjunkie's Avatar

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Removing fungus from Pentax-FA f4,7-5,8 100-300mm "silver"

Bought this lens after trying its shorter sibling (FA silver 35-80mm).
It came with tho evident fungus spots, in the middle of a glass hopefully located inside the front assembly.
I don't have my tools with me, no good screwdrivers, no spanners, etc etc, so i have to postpone, though i'd like to know in advance if the glass elements in front of the diaphragm can be easily dismantled and cleaned.
If the elements are held in place by retaining rings and can be accessed from the front, i will bring the lens with me when i have to go back home, and i will try to do the work myself. If not, i might keep the lens as is and use it when i'm afraid a more valuable objective could get damaged.
From what i've seen, if i avoid flare shading the front glass, IQ is quite good, much better than expected



Last edited by cyberjunkie; 11-15-2017 at 05:57 AM.
11-14-2017, 10:06 AM   #2
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You will need a spanning wrench to remove the elements.
11-14-2017, 07:38 PM   #3
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If it is like its other sibling, the 80-320 then the front element cluster will be sealed inside of a cuff. I attempted to clean my 80-320mm last year due to fungus, but the fungus was inside that front cluster and couldn't be disassembled. Please be extremely careful.

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