Correcting marked elements

Used camera lists contain a large number of quality lenses with marked front and rear elements. As these are much cheaper than better examples I've often wondered how difficult a glass element is to polish out. So far I've not been tempted but the price of mint condition wide aperture lenses makes the idea more appealing.

Does anyone have experience of undertaking such work?

I would think that the coating on most lenses makes it impossible to polish the glass. If there was a way to do this, these lenses wouldn't be so cheap.

Re-polishing is really not the way to go (as it also changes the lens curvature).

Light marks, if few,have practically no effect on final results.
Several light marks *can* reduce contrast and increase haze, particularly in difficult light situations (against light, etc.).

A (very) few deeper scratches can be filled with black paint with no ill-effect apart from an insignificant loss of speed.

Widespread "cleaning marks" or fungus are really bad news and are best avoided (though a spot or two of light fungus can often clean up quite well).

Generally, marks on the rear element are far worse than those on the front one.

I have several lenses with filled deep scratches... A great way to get top-end lenses cheap!

Thanks for all the replies. I recently returned a very cheap, very scratched f1.4 lens that came with a Nikkormat. Perhaps I should have tested it first? The front element looked like it had passed through an angle grinder - maybe it would have made a good portrait lens!

So long as the shop offer a right to return I may be more liberal in my attitude to marked glass after reading your replies and PMs. Thanks again.