FreeLists / opendtv / [opendtv] Re: Red camera lenses

["johnwillkie" <johnwillkie@xxxxxxxxxxxxx>]

Dan was talking about lenses without focal points, and I said that I knew of
no such thing.  I was kind of waiting for someone to point out that the
focal point of some telephoto lenses is between the front lens element and
the subject.

 

So, I guess you changed the topic, since I never said anything about exit
pupils, only that laser lenses are different than the ones we use, since
they DO use light in parallel rays.

 

John

 

  _____  

De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En
nombre de flyback1
Enviado el: Wednesday, June 20, 2007 5:10 PM
Para: opendtv@xxxxxxxxxxxxx
Asunto: [opendtv] Re: Red camera lenses

 

Don't know where you got the idea that some camera lenses have no focal
point. All I pointed out is that in telecentric lenses,
the primary light rays leave the exit pupil in parallel lines. That is the
idea conveyed in both of these sites.
Cliff Benham

johnwillkie wrote: 

Bad guess.  I visited both sites, scanned both pages.  I saw, on BOTH, a
lens diagram with a focal point, and what appeared to be an image that was
upside down from the source.  

 

What subtle issue did I miss with these instrumentation cameras?  How
macro-focusing desires all too easily lead to "bug's eye" lenses?

 

John Willkie

 

  _____  

De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En
nombre de flyback1
Enviado el: Wednesday, June 20, 2007 12:42 PM
Para: opendtv@xxxxxxxxxxxxx
Asunto: [opendtv] Re: Red camera lenses

 

johnwillkie wrote: 

Thee are lenses without focal points?

 

John Willkie

 

  _____  

De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En
nombre de flyback1
Enviado el: Saturday, June 16, 2007 12:52 PM
Para: opendtv@xxxxxxxxxxxxx
Asunto: [opendtv] Re: Red camera lenses

 

Read about Telecentric lenses:
http://www.lhup.edu/~dsimanek/3d/telecent.htm
<http://www.lhup.edu/%7Edsimanek/3d/telecent.htm> 
http://www.computeroptics.com/telecentric.html







I guess you didn't bother to open and read from either URL...