From: Christina Z. Anderson (zphoto@montana.net)
Date: 12/17/02-11:30:19 PM Z
<Joe Smigiel snip>
> One key point that I haven't seen discussed here is that*perspective* has
nothing to do with lens focal length, telephoto design, etc. Your
perspective only depends on your physical location in space. There is
really no such thing as "wide-angle," "normal," or "telephoto" perspective.
All lenses (or pinholes for that matter) will have the same perspective if
located physically in the same point in space. A 6" lens or pinhole camera
will have the same perspective as a 3" or 12" or 24" lens/camera if they are
located at the same point. but as long as you are in the same physical
spot, all focal lengths will produce the same perspective.>
I thought, Joe, that if you stood in the same spot and switched lenses it
would increase and decrease apparent perspective. In other words, to
accomplish the same perspective with different lenses, you would have to
move your body with camera further back or further forward to get the same
exact size of scene in your viewfinder and only then would perspective be
the same. It is the distance from camera to subject that creates
perspective, not the lens, but if you are standing at the same point as you
say, above, perspective will change. Hence, in practice (not theory) focal
length, standing at the same point in space, does change perspective. Maybe
it just changes the relative size between objects, but our eyes still
perceive that as perspectival change, in practicality. Please correct me if
I have this wrong. I used to, also, believe that DOF for the same reasons
did not change; in other words, if you had a 28mm lens on your camera, and
then switched it to a 100mm lens and stepped back far enough so your subject
in the viewfinder was exactly the same size as when you were using the 28mm
lens, that DOF would be exactly the same. Then I find out that this is not
true, according to this website:
http://dfleming.ameranet.com/dof_imagesize.html which states that "wide
angle lenses do provide more DOF than telephoto lenses, when subject
distance is greater than approximately 1/4 of the hyperfocal distance of the
shorter lens."
Chris
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