lens so that the littlefinal aspherical element group can help collimate
the light as it leaves the lens.
collimator
[ ˈkäləˌmātər ]
NOUN - A device for producing a parallel beam of rays or radiation.
Colilimated Light - Collimated light is light whose rays are parallel..
Telecentric lens - A telecentric lens is a compound lens which has its
entrance or exit pupil at infinity
.. none of these things require any form of focusing to form an image.
It's a simple experiment, anyone can do in no time at all - shine a laser
light through the lens - if it doesn't focus at all distances, the lens
simply is not producing parallel beams of light and is in fact a normal,
everyday lens.
For all the hulabaloo, claims, counterclaims etc etc, there is no credible,
referenced, verifiable validation of claims that digital lenses produce
anything other than converging focus images like any old film lens
To put it even more simply, yes a 1000mm long lens on a 35mm has light rays
*closer to* parallel than the 100mm or a telephoto, that doesn't mean the
light is parallel, collimated, the lens is telecentric or anything else
other than the lens behaves this way because of it's old design. A
telephoto design will have the final element a lot closer to the flm plane
than the old long lens and thus the angle the light spreads is at a greater
angle..
I have 2 minolta 24mm lenses, one requires the mirror to be locked up and a
viewfinder used because the lens is a primitive design, later lenses moved
the element further from the film plane. Again, the light rays are *closer*
to parallel, but they are simply not parallel or collimated.
here are some
Telecentric Visionmes Lenses:
http://www.zeiss.com.au/camera-lenses/zh_hk/industrial_lenses/telecentric_lenses.html
and another mob
http://www.opto-engineering.com/resources/telecentric-lenses-tutorial
Another this of course is as Pablo mentioned, using the center of old lenses
on smaller formats is going to produce some good images - and again bear in
mind .. mounting a Sony NEX lens to an NEX camera has the lens sitting quite
close to the sensor. Putting on say an old Novoflex with an NEX adapter
will probably have the rear element sitting 10 times further from the
sensor - again, the light used to form the image will be a lot closer to
parallel in the latter case.. still not collimated or telecentric though
