Chipped coatings - how serious?

I have just noticed that one of my lenses has a couple of chips the size of grains of rice (easy cook fortunately rather than long grain)out of the coating.

The lens still seems to produce reasonable pictures to my less than perfectly critical eye.

What sort of image degradation should I be looking for?

In terms of the area of the front element the actual area obscured may be quite small. The biggest danger might be flare around the defects.

The traditional remedy is to get some black paint and very carefully fill in the defect. This will reduce the visibility of the defect.

Needless to say, it's not ideal.

Whatever happened?

The only thing I can think of is that I went to put the lens cap on with the hood still on (mea maxima culpa:blush and fumbled it.

Ooh er - putting paint on it sounds a bit scary!

Next time I'm out with it I'll try to provoke a flare.

I've never actually attampted this, so you're on your own!

Maybe an insurance claim would be less painful?

maybe I misunderstood this. Should he put black paint on the lens coating? Are you perhaps thinking he meant the casing of the lens rather than the glass? I understood him to mean the glass coating (the SMC part), not the barrel of the lens. Or am I missing something?

The idea is to fill in a small defect in the glass coating with black. That way light won't reflect off it and cause a flare spot.

So yes, you paint the glass. However, very minimally and only to fill the defect, a bit like fixing a chip on a car windscreen.

I can see the theory behind John's suggestion I think. Presumably it is better to have no light passing through that area rather than unregulated light.

I might try putting some small pieces of paper over the chips first and see if that makes me feel any braver.

It's my Sigma so it's not actually SMC coating.

Thanks for the advice.

My Dad always told me he used to paint out lens defects with black paint - sounds mad but apparently it works! Like John I haven't actually done it myself though...

Black paint is sometimes used to cover serious defects in lenses, such as chips in the glass, which would scatter a lot of light. Damage to the coating probably won't actually scatter much light, just slightly increase the the strength of specular reflections from the surface. This will increase the level of any flare and reduce contrast. If it's a small defect then most of the lens area is still coated, and I would expect any effect to be very small, and probably completely undetectable.

If you can't see any degradation of your images then I wouldn't worry about it (although it will obviously reduce the resale value - but not as much as putting black paint on it!).

Leica used to recommend MATT black paint.
I'm quite sure that it should only be used on the
front element. There could well be a reaction with
coatings.

shim

A Sharpie can also be used. Much easier to control where it's being applied.
Yes, I've done it. Bad scratch, and it worked well.

If you're sceptically that a bit of paint will be shown on the photo. simply lay a small piece of paper (half the size of your nail) on the front element of the lens and take a photo, wanna bet that it wont show up