where is entrance pupil point on 17-55 f/2/8 please help

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lukx
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p.1 #1 · where is entrance pupil point on 17-55 f/2/8 please help

I bought nodal ninja sytem for taking panoramas and I need to set it up properly (http://www.nodalninja.com/html/canon_settings.html)
Does anyone know where is entrance pupil point on canon 17-55 f/2.8 lens?
Many thanks for help in that matter.

Oct 11, 2008 at 01:44 PM

rkgatteleport
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p.1 #2 · where is entrance pupil point on 17-55 f/2/8 please help

Hi,

Did you try the "normal" method for determining the parallax correction already
(you know, find a near and far object, swing the camera so the items move from
one side to the other , and adjust until the two objects don't "move" relative" to
each other)?

I'm not sure there is one number anyway - doesn't the pupil move depending on
the focal length on this particular lens?

FWIW, if you are using modern stitching software, you don't have to be terribly
precise on your parallax corrections to get acceptable results...

Best,

rkg
(Richard George)

Oct 11, 2008 at 03:04 PM

Roland W
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p.1 #3 · where is entrance pupil point on 17-55 f/2/8 please help

A fast way to get close is to set your aperature to F22, and do a stop down of the diaphram of the lens with the depth of field preview button. While stopped down, look into the front of the lens, and estimate how far into the lens the diaphram blades appear to be located. Tilt the lens from side to side to help with your guess. That process will produce a very good estimate. From there, if you need to, you can use the standard process to refine it. And yes, most zoom lenses change when the focal length is adjusted.

Oct 11, 2008 at 03:59 PM

lukx
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p.1 #4 · where is entrance pupil point on 17-55 f/2/8 please help

Ok thank you

I got it .

Oct 11, 2008 at 06:32 PM

dcains
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p.1 #5 · where is entrance pupil point on 17-55 f/2/8 please help

Roland W wrote:
A fast way to get close is to set your aperature to F22, and do a stop down of the diaphram of the lens with the depth of field preview button. While stopped down, look into the front of the lens, and estimate how far into the lens the diaphram blades appear to be located. Tilt the lens from side to side to help with your guess. That process will produce a very good estimate. From there, if you need to, you can use the standard process to refine it. And yes, most zoom lenses change when the focal length is adjusted.

Also, if you have the aperture stopped down, and remove the lens from the body while holding the DOF preview button, the aperture will stay stopped down with the lens off the body.

Oct 11, 2008 at 07:26 PM


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