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Novel application of compound lenses for DOF

 
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DQE



Joined: 08 Jul 2008
Posts: 1653
Location: near Portland, Maine, USA

PostPosted: Sun May 05, 2013 7:42 am    Post subject: Novel application of compound lenses for DOF Reply with quote

An interesting article on compound lenses to achieve "infinite depth of field":

http://www.bloomberg.com/news/2013-05-03/bug-eyed-camera-with-200-lenses-seen-improving-surgery.html

Is there some way to adopt such a thing to high-resolution macro or micro photography? It would be ironical if we adopted a compound-eye system to photograph bugs' eyes!

Does it really have good detail with its "infinite depth of field"? Is this better performance than would be achieved **at a fixed light level** with a conventional camera system, perhaps while using abnormally small aperture? Perhaps a very wide-angle lens would be the best reference point for a conventional camera/lens system?
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rjlittlefield
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Joined: 01 Aug 2006
Posts: 18095
Location: Richland, Washington State, USA

PostPosted: Sun May 05, 2013 9:45 am    Post subject: Reply with quote

As written in the article:
Quote:
In traditional photography, lenses can focus only on one distance, with a decrease in sharpness on either side of that point. In the compound eye, the depth of field is infinite, so nothing is out of focus, Rogers said in a telephone interview.

I'm going to be generous and assume that some context was lost between what the researcher was thinking and what we're seeing in the article.

By our usual interpretation and standards, what's written in the article is nonsense.

However, I can coerce it to make sense by interpreting "depth of field" as meaning "able to resolve the same size of subject detail at all distances", as discussed by Harold M. Merklinger in "The INs and OUTs of FOCUS", downloadable HERE. On pages 25-38, Merklinger points out that if a lens is focused at infinity, then its geometric "disk of confusion" in object space is a constant value equal to the diameter of the lens aperture. On page 30 he demonstrates that this approach provides equal ability to recognize a person at all viewing distances, limited only by diffraction and sensor resolution at long distances.

So, if you're a dragonfly and you want to recognize prey at a wide range of distances, then it could make sense to have optics focused at infinity and limited to resolving the size of an entire eye facet at best. Such a lens would have "infinite depth of field" in the sense of Merklinger, but would have resolution around 2 orders of magnitude less than we're used to getting with close-focused wide aperture lenses like microscope objectives.

Thanks are due to Harold Gough for pointing me to Merklinger, in his post HERE.

--Rik
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Harold Gough



Joined: 09 Mar 2008
Posts: 5787
Location: Reading, Berkshire, England

PostPosted: Sun May 05, 2013 10:27 am    Post subject: Reply with quote

This is the version I saw last week, with, I feel, somewhat more-restrained claims:

http://www.bbc.co.uk/news/science-environment-22372442

Harold
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