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09-18-2014, 07:20 AM   #1
8540tomg's Avatar

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Fungus or Lens Separation

I'm looking for some advice on a lens separation or haze/fungus issue.

I have an old SMC Pentax K 300/4 lens which I purchased about thirty years ago. The lens was used at the time but was in great shape. It did have one small issue however. At the extreme edge of one of the internal elements there seemed to be a small spot of haze about the size of an eraser tip. It didnít seem to affect the images so I gave it little thought.

About fifteen years ago I sent the lens in for cleaning and specifically noted the spot. The firm said the lens was fine and sent it back. As the spot didnít seem to have changed over the years I assumed all was well and ignored the issue.

That was about ten years ago. Yesterday when I was looking through my gear I picked up the old 300/4. I hadnít used it for some time and thought I would take it out for a spin. Naturally I held it up to the light to take a look at the haze spot to see if there had been any changes. To my horror it seems to have grown to the size of a thumb print now. It even seems to be sending streamers toward the center of the lens.

This raises a few questions:

Is this a fungus or lens separation?

Can it be cleaned or repaired by sending it to Eric or some other repairman.?

Is it worth the cost of repair or do I just continue to use it as is?

Iíd appreciate your thoughts/opinions on this one.

Tom G

Last edited by 8540tomg; 09-18-2014 at 08:08 AM.
09-18-2014, 08:41 AM   #2
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Can you post a picture?
Sounds like separation but it is impossible to tell without seeing a picture.
Normally the consensus is "do not touch it unless it affects picture quality"
09-18-2014, 10:37 AM   #3
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The front three elements (everything in front of the focus ring) unscrew without tools. Slide the hood out and grab there, grab the mount end with the other hand and twist like you're opening a jar. Then you can at least see two internal glass surfaces - once you open the aperture. If the haze spot is in the front group, it's fungus because the glued elements are in the other half.

I'm not sure a repair is worth it either way. Fungus over that long probably etched the coatings, and separation is not an easy repair. I don't know the current market value but these used to be less than $200 used.
09-19-2014, 10:51 AM   #4
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Original Poster
Thanks guys,

I may give the disassembly a shot.

I can always send it to Eric if I really screw up.

Tom G


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