Are these rear element lens scratches and do they matter?

Question

I got a used Nikon AF-S Micro NIKKOR 60mm 1:2.8 G ED lens, but notice these scratches on the rear element:

Am I correct that the white marks are scratches and will these matter or will blur of unfocused light make them irrelevant? If these are scratches, can the lens be repaired to replace the scratched glass at a reasonable price?

Here is what sky looks like through this lens at f-32 after cleaning the image sensor with compressed air:

The black dots appear to all be from the sensor, so other than those, I think the scratches, if they are scratches, cannot be seen, but perhaps this is not the way to see them?

Answer 1

Am I correct that the white marks are scratches and will these matter or will blur of unfocused light make them irrelevant?

It's not clear what those marks are from the picture. Run a fingernail lightly across them. If you feel them, they're scratches. If not, they're coating marks or reflections. Your fingernail should be softer than the glass and should not scratch it.

Whatever the marks are, they seem minor enough that they may not be noticeable, even with the lens stopped down. There are a few defocused blurs in your test image, but it seems your sensor may be dirty. Consider cleaning it.

If these are scratches, can the lens be repaired to replace the scratched glass at a reasonable price?

There is no cheap, easy way that I know of to repair scratches. I've read of attempts using windshield repair kits. It might be worthwhile for chipped glass, but not for tiny marks like these. Applying chemicals to the lens would risk damaging it.

If the marks bother you, you can swap elements with a broken, dysfunctional lens. However, by making such an attempt, you would risk ending up with two dysfunctional lenses.

Answer 2

Viewing scratches on the back lens is much more difficult than on the front lens. Your best bet is in-focus black&white crosshatch pattern at various distances and hatch sizes and various exposures. The scratches will cause black to bleed into white and vice versa, but it depends on lens and focus how strong the effect is and its strength tends to be inverse to its spreadout.

Answer 3

Short answer: No! scratches on the lens front or rear elements don't matter as much as most people think.

If you are considering buying this lens, you should go ahead especially because with scratches on the lens element, I presume it will be available at a bargain.