Reviving lens marred by fungus or scratches.
I'm wondering whether it is possible to repair the surface of a lens
that has been scored by fungus, or scratched, to minimize flare
when using the lens. I have a 75/4,5 Triotar in an Art Deco Rolleicord
that had fungus -- the fungus was cleaned and the lens looks clear
but it is a flare monster. From other photos I've seen online taken
through a Triotar, it shouldn't be so flare-prone as mine, and so I
am assuming that fungus and scratches have left the lens surface
in a condition that causes the flare.
So: Possible? And if possible, who (in the US) does it?
Many thanks in advance for your thoughts.
I haven't done it, but in my research the following source showed up:
If you can see the flaw, like a pit or scratch, then you can obliterate that portion of the lens with something like India Ink.
Obviously this also reduces the overall light transmission of the lens, and clearly isn't suitable if there is a substantial portion of the surface damage.
But if the spots are limited this ought to work fine. It's essentially going to cost you a partial stop.
Now, if the coating is gone and it just flares like an old fashion inflated triplet then I suggest you look for the old creamy dreamy look and save your money.
If the lens flares, it's probable that any coating was either destroyed by the fungus, or removed by whatever process was used to remove the fungus. Thake the lens and shine a penlight thorough it, is there a haze or fine scratches covering the surfaces? Haze can be cleaned, but fine scratches will cause flare and loss of contrast and there's nothing you can do except use a lens shade.
Originally Posted by Rolleiflexible
Jon, that's what I was looking for, thanks. To the other responders,
Originally Posted by Jon Shiu
a Triotar from an Art Deco Rolleicord is a 1930s-vintage lens -- it's
an uncoated lens. A lens hood doesn't do the trick. I'm thinking
that Focal Point may be able to resurface the lens. Or maybe I'll
luck out and find an old Rolleicord with a Triotar I can cannibalize
for the camera.
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The service Focal Point advertises is for repairing the coatings. Repolishing a lens with scratches is not really feasible, as removing the glass neccesary to eliminate scratches changes the formula of the lens. Also, it's expensive.
Originally Posted by Rolleiflexible
Fungus damage can be removed by using cerium oxide mixed with water as a polish. People make telescope mirrors all the time and the final step is polishing. Check the web for suppliers. As mentioned above the coating will have to be re-applied. When I was in graduate school I had to polish sodium chloride optical windows all the time. Only difference was using ethyl alcohol instead of water. (Sodium chloride transmits infra-red light while glass will not.)
A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.
~Antoine de Saint-Exupery
I have been able to remove light fungus and marks using toothpaste and a damp cotton swab. So long as the glass isn't etched by the fungus, toothpaste should be able to clean things up. If you are cleaning the inside surfaces, scrub lightly in a circular motion, and take care not to damage the coating.
if it looks clean, then you're better off $elling it to a $ucker and buying a good one. Lens polishing/grinding is always more expensive than getting a new lens in most cases.
try the toothpaste trick first, though, you have nothing to lose. Sounds like it'll work--never tried it but...sounds promising, particularly if you have nothing to lose.
Be careful. Some toothbrushes have abrasives that can harm your lens further. When I was a child I used Ultrabright toothpaste to "brush" the paint off a toy car (an Hot Wheel).