P3D Re: Lme Kbee super wide angle

["Matthew V. Ellsworth" <oakridge@xxxxxxxxxxxxx>]

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Oliver Dean wrote:

You probably won't be able to find achromat
viewer lenses capable of covering medium format (2 1/4' x 2 1/4") at
only 30 mm focal length for anything less than a fortune, if at all.
Viewer lenses have different requirements from camera lenses, because
the image being viewed is a virtual image rather than a real image, and
is, therefore, subject to having the view of the corners severly cut off

if the lens diameter is not large enough.  Viewing a medium format image

with a 30 mm focal length lens would require a lens diameter much larger

than the focal length in order to see all corners of the image, which
means a maximum lens aperture of less than f/1.0, and such lenses are
difficult and expensive to design.
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Oliver (and anyone else with some thoughts on this)

Before I have time to bring my optics education up to speed --
Could you give me some idea of what you think the shortest (reasonably
affordable) focal length achromat lens for viewing 2 1/4" images would
be?  (Ignoring corners, just side to side, top to bottom)

Also, seems like this might vary between those that wear glasses and
those who can get their eyes closer to the lenses.   How would one
figure out that difference?

Matt



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______ Matthew V. Ellsworth ______________________________
      oakridge@xxxxxxxxxxxxx      http://www.oak-ridge.com