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Lens defraction exposed!

 
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Jbailey



Joined: 05 Jul 2008
Posts: 520
Location: Wisconsin, USA

PostPosted: Wed Jul 23, 2008 8:07 am    Post subject: Lens defraction exposed! Reply with quote

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.




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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