Rear element scratch
I keep hearing that a rear element scratch is much more horrific than a front element scratch. This sounds logical but does anybody have any first hand accounts about rear element scratches that they could share?
From what I can find front element damage usually results in flare and loss of contrast/sharpness, if any impact at all. Rear element problems seem to get very vague. 50/50 opinions on running for your life or using it with no noticeable effect.
You could probably use it and not notice anything. Just to be safe, an old trick is to fill the scratch with something opaque like Indian ink so it doesn't pass any light.
I have a lens on which there is a scratch on the rear element. The scratch seems not that deep and probably affect only the coating. I did extensive testing to see if the picture quality was affected and I've not been able to see any degradation of the image.
I've got an example of the legendary Nikkor 105mm f/2.5 with a cluster of marks/scratches on the rear element. I set one of my Nikon bodies up on a good tripod and took shots with the 105mm and my Nikkor 80-200 f/2.8 (itself a stunningly good performer, and this example in excellent condition with no marks or dirt on any element), zoom set so the viewfinder contents were the same as with the 105mm.
Results, even of a detailed scene, were indistinguishable to my eye between the two lenses. Using a D70 body and viewing on the computer at 100% showed a very slight edge in sharpness and contrast in favour of the scratched 105mm.
Don't worry about it!
You can get away with quite a lot. On another forum, someone posted an image and asked if anyone thought anything was wrong with it. A bit further down, he posted a picture of the front of the lens he took it with.... together with the smashed polarising filter which was fitted at the time.
There were no signs of anything wrong in the actual image.
Therefore, a few scratches or even air bubbles are not going to have much of an effect.
Rear element scratches tend to cast a shadow on the film.
Front element scratches do not.
Front elements scratches can be a nuissance because the edges reflect light. Which is why filling them in with helps.
The edges of rear elements scratches could reflect light too, but filling them in does not help with the shadow problem.
Originally Posted by Q.G.
Rear element scratches are nasty and not welcome on your optics at all.
Logical, but just more rumors to me. Do you have any examples or first hand accounts of this problem?
Originally Posted by Krzys
If it is that logical, why do you need examples?:o
Do you have an old optic? Scratch it, test and see for yourself, as for examples, no I don't have, I do take care of my optics!:D
Because I am interested in seeing pictures or tests showing the ill effects or at least stories detailing them. There are some front element damage tests floating around, but no rear element.