Lens condition

[John Adolfi]

Could someone from experience or from a good reference source share with the onlooking world the affects of a scratch on a lens and its impact on the quality of the recorded image. Is one small scratch(1-2mm) ok? How about several pin size marks on the outer element? How much does a small smudge, dirt or a single fingerprint affect it? How critical is it?

Edited September 17, 2005 by John Adolfi

[Stephen Williams]

Could someone from experience or from a good reference source share with the onlooking world the affects of a scratch on a lens and its impact on the quality of the recorded image.  Is one small scratch(1-2mm) ok? How about several pin size marks on the outer element?  How much does a small smudge, dirt or a single fingerprint affect it?  How critical is it?

<{POST_SNAPBACK}>

 

Hi,

 

Very light scratches are probably OK. Larger ones can effect the image and will flare very easily. A small smudge or fingerprint is like a slight softening filter.

 

Stephen

[Steven Budden]

It isn't generally that crucial because the front element isn't in focus. Whatever is there is very soft and blurred and light pours in around it.

 

When I began filmmaking I would not accept a lens that was less than spotless... I sold a lens which had fungus inside. Then the person who bought it showed me footage he had taken and the fungus, which looked fairly annoying on the lens, didn't show up at all!

 

Rear element flaws I guess are more of a problem because they're nearer to the film plane and therefore less forgiving.

 

Depends on what you're shooting too. If you're shooting a clear sky then specs may show up, whereas if you're shooting an architectural scene or a forest they may not.

 

Steven