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Forum: Pentax SLR Lens Discussion
02-24-2019, 10:59 AM
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Thanks guys - I gave it a go - sadly its starting to look like a spot of oil now. Its weird because the diaphragm blades look dry in there and I would swear the spot is appearing on a glass surface well away from the diaphragm on the other side of a lens. Its hard to know for sure because there is so much glass in this lens and the internal reflections under light are quite baffling. It could be a tiny spot near the diaphragm thats just being magnified or a bigger spot further up the lens.
I know its bonkers but I am going to pay up to get the lens cleaned. Its madness really because I could buy a more modern zoom for less but I like to repurpose/reprocess as much as possible.
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Forum: Pentax SLR Lens Discussion
02-17-2019, 03:35 PM
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If it is fungus that might work but there is also some haze on the rearmost inner element - I can't be sure what fungus looks like in a lens never having seen it. This looks like a small milky spot but the spot has grown in size. Initially I thought it was a tiny mote of dust but its definitely getting bigger which makes me suspect fungus.
I could try the UV route but in many ways I'd far rather get whatever it is removed for good.
If I went the UV route what do I use - just a UV light in a box ?
Mel
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Forum: Pentax SLR Lens Discussion
02-17-2019, 10:22 AM
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Hi People,
I acquired a Sigma Mini-Zoom some time ago which has an unusual range of 39-80mm - that makes it not quite a wide angle and also not quite a telephoto. Its a bit of an oddball and my reading has led me to believe this was quite an early zoom from around 1980. I have used the lens a bit and fallen in love with it. Its almost a work of art in construction, made of metal with 4 separate rings (focus, zoom, macro focus, aperture). Unfortunately I noticed a few days ago what looked like an oil spot on one of the inner lenses but am now convinced its actually fungal growth. The lens was spotless when I acquired it so why its developed this is a mystery as its kept under good conditions for a lens.
More crucially I would really like to get this fixed - the spot would appear to be ahead of the diaphragm but its hard to which lens has the spot my guess is its either on the rearmost lens of the 2nd main group on the attached pic or the front lens of the third main group. Either way getting inside the lens is essential. I have searched the web and found no reference material for taking this one to bits.
The lens isn't valuable so its unlikely to be economic to get a tech to look at it so if I am to fix this I need to do it myself I guess. Has anybody out there got any experience with this lens, any guides you may have seen etc as I would hate to lose this lens and although I am pretty handy with tools and fixing cameras I am a bit reluctant to go in blind on this one.
Any help appreciated - thanks
Mel
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