Lens defraction exposed!

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Jbailey
Posts: 520
Joined: Sat Jul 05, 2008 6:45 am
Location: Wisconsin, USA

Lens defraction exposed!

Post by Jbailey »

Here's a view of the light defraction around the iris diphragm in a camera lens. The lens is set for F/5.6. You can imagine how proportionally much more of the lens' image-forming area would be taken up by the difraction bands at F/22! This is why smaller lens openings can cause loss of image sharpness.


Image

The circles are likely caused by a few dust specks on the lens. The difraction bands are made visible by using near-monochromatic light from an LED and some crude collimnation tricks.

Jim

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