What are faint streaks on a vintage lens front element, and can they be removed?
Asked 1/17/2019
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2 answers
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I have a Tamron SP 35-210mm f/3.5-4.2 BBAR MC lens from the 1980s. The front element shows faint streaks that are only visible when light hits the surface at certain angles. They do not look like normal scratches, and the lens appears fine in ordinary lighting.
I have already tried cleaning with peroxide, vinegar, 70% and 90% isopropyl alcohol, detergent, and water, leaving each on briefly, but the marks do not come off.
Are these likely to be cleaning marks, coating damage, or possible fungus damage? If so, is there any safe way to remove them, or is professional recoating the only option?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
7y ago
2 Answers
5
Upon close inspection of the provided images, it appears that someone has tried to wipe the lens element with the wrong tool. This left light streaks on the surface of the element. From that perspective, you now have several choices from safe to diy depending on the value of the lens (your affect/price).
Safest: leave it as is
Small streaks like these should not change the lens properties. If you don't mind the lens look and/or don't have the money, the safest solution is to keep it as-is. You probably won't notice it in your photos.
Safe: professional re-coating
If your lens is vintage and you want this lens to have a brand new look, you can ask an optic professional for re-coating the lens (under 100$ but can take a while). Vintage lenses are easier to re-coat than modern ones due to softer and more primitive coating techniques (as opposed to multi-coating, oil free treatment and hard metal based coating).
Safe alternative: get another copy
If this lens is not rare and rather inexpensive, you may consider buying another copy that looks good.
DIY: remove coating yourself
The flare-loving community has a few tutorials on how to remove the lens coating. This lens specialized shop has a good one. Beware, removing lens coating is an abrasive process, not chemical. It can make your element non-spherical, introducing additional optical aberrations to your lens. This educative page illustrates the process, the result and the risks associated to this kind of operation.
Other information may be found in this interesting thread on photrio.
Originally by user81063. Source · Licensed CC BY-SA 4.0
user81063
7y ago
0
Generated from our catalog & community — verify before relying on it.
The marks are most likely damage to the front-element coating, not dirt or residue. Based on the streaky, directional appearance, they were probably caused by improper wiping with an abrasive cloth or particles trapped in the cloth. Some of the spotted patterns could also be old fungus damage, which can etch coatings.
If repeated cleaning with normal lens-safe liquids did nothing, that strongly suggests the marks are not removable deposits.
Practical options:
- Leave it alone: minor front-element coating damage often has little or no visible effect on image quality.
- Have it evaluated by an optical repair specialist: recoating or element replacement may be possible on some vintage lenses.
- Avoid further DIY cleaning or polishing: you’re more likely to worsen the damage.
If fungus is suspected, keep the lens away from other gear until it has been inspected/cleaned, since spores can spread.
So: these streaks are probably permanent coating damage (possibly with some fungus etching), and they generally cannot be cleaned off at home.
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UniqueBot
AI7y ago
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