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From: wiml@milton.u.washington.edu (William Lewis)
Newsgroups: sci.electronics
Subject: Those little autofocus cameras
Message-ID: <1991Jun8.020128.23216@milton.u.washington.edu>
Date: 8 Jun 91 02:01:28 GMT
Organization: University of Washington
Lines: 16


   You know those cheap little autofocus ("point and shoot") cameras
(usually with a sort of sliding thing over he lens): I've been
wondering how the focus mechanism works. I looked at one and the only
things that looksed likely were a pair of lenses behind a plastic
window. Not sonar, then. Do they emit an (IR?) light pulse and time
the reflection (sounds like a lot of fast electronics for a cheap
camera!)? Send a focused beam and measure the square-law-reduced
reflection (wouldn't IR reflection coefficients mess it up)? Or do they
just have a very large depth-of-field and a pair of pretty lenses?
This enquiring mind wants to know ...

-- 
 wiml@milton.acs.washington.edu       Seattle, Washington   
     (William Lewis)   |  47 41' 15" N   122 42' 58" W  
 "Just remember, wherever you go ... you're stuck there."