T3D Re: (Matched lenses?)TECH-3D digest 501

[bobh@xxxxxxxxxxxxxxxxxx]

RE: Ray wonders if it is possible to buy 'matched focal length' 
lenses?  This would be pretty expensive it a lot had to be searched 
for matched pairs. And with new zoom technology practically 
impossible. It has now come to light that internal focussing lenses 
often have only the marked maximum zoom focal length at 
INFINTY (where they are rated) and on focusing closer that focal 
length (and image size) changes. In lenses of 35mm cameras it 
has been shown that a 200mm lens is actually 135mm at 10 feet, 
but 200mm at INF. when set on the 200mm position. (they hoped 
we wouldn't notice??)
 I don't know what kind of video you have that allows a lens change, 
but a fixed focal lenght has the been chance of a matched pair.. 
BobH
 Specs at INF usually allow 5% variation..this may not be all that 
noticable to a viewer. I have one eye lens inplant and one normal 
eye and corrected with contact lenses the mismatch seems ok in 
viewing stereo in viewer.  With glasses rather than contact lenses it 
is intolerable..so I never bother with glasses (to be used before 
putting in contacts.) RLH
Bob Howard (bobh@xxxxxxxxxxxxxxxxxx)
SEND NO PIX OR PROGRAMS TO LIGHTSIDE!!
 Instead send those to:
robhoward@xxxxxxxxxxx  or   bobh626@xxxxxxxxxxx


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