How much does a scratched lens effect IQ

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Donki

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Ian
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Hi guys,

I have seen a lens at a good price, only problem is there is a small (5mm) scratch on the front element near the centre of it, the seller states that picture quality is uneffected and the pictures that have been supplied show this. Can anyone say for certain that IQ will be uneffected?

Cheers Ian
 
What is the lens? It'll tend to be worse on a wide lens (anything on the front element is in greater focus). Otherwise, as long as it isn't causing serious reflections you might not notice it. You can always try painting the scratch black so it isn't part of the optical formula.

Near the centre is annoying I imagine...it'll be there (or not there) at all apertures.
 
Mud said:
What is the lens? It'll tend to be worse on a wide lens (anything on the front element is in greater focus). Otherwise, as long as it isn't causing serious reflections you might not notice it. You can always try painting the scratch black so it isn't part of the optical formula.
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On a wide lens with more DOF i can see why it would be more likely in focus, but wouldn't it be magnified on a tele lens ?
 
Donki said:
Hi guys,

I have seen a lens at a good price, only problem is there is a small (5mm) scratch on the front element near the centre of it, the seller states that picture quality is uneffected and the pictures that have been supplied show this. Can anyone say for certain that IQ will be uneffected?

Cheers Ian
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It'll be fine in some situations, but very detrimental in others, for example with a light source in frame the flaire may be pretty bad, certainly worse then the maker intended. How much you can tolerate this may of course depend on the price
 
Its a Canon 85mm Prime, just dont know whether to risk it, its from a local "cash converting" shop :) lol. I just dont know wheather to risk it, they will do a refund but only for credit not cash.
 
Thmaga said:
On a wide lens with more DOF i can see why it would be more likely in focus, but wouldn't it be magnified on a tele lens ?
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Ever tried shooting a telephoto through a wire fence? As long as the fence is far from your focal plane you can usually get away with it.
 
Donki said:
Its a Canon 85mm Prime, just dont know whether to risk it, its from a local "cash converting" shop :) lol. I just dont know wheather to risk it, they will do a refund but only for credit not cash.
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Depends how cheap it is and the margin over a good one, CPS will probably change the front element for £90 all in
 
Donki said:
Its a Canon 85mm Prime, just dont know whether to risk it, its from a local "cash converting" shop :) lol. I just dont know wheather to risk it, they will do a refund but only for credit not cash.
Click to expand...

Could you go and ask them can you try the lens at all different apertures, at least then youd have an idea of it capabilities
 
Just Dave said:
Could you go and ask them can you try the lens at all different apertures, at least then youd have an idea of it capabilities
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I might do that, to be honest it only seems to be about £40 cheaper than other second hand ones on here and on Flea bay so probably would be better paying the extra. I am the kind of person that tends to obsess (not a nutter) on small annoying things so I dont think I could get ever use the lens without thinking about it. I will call in tomorrow after work and see it in the flesh.
 
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