P3D Re: boris starosta's site

[bercov@xxxxxxxxxxx (John Bercovitz)]

Dr.T writes:

> The perspective matching that he strives to achieve with
> his 50 mm taking and viewing lenses is going down the hill 
> when I view his web site with crossed eyes from 20" away. 

It's dead simple to figure either, from what distance you must 
view or, what lens you need.  Perhaps Boris would be interested.

First from what distance you must view:
If you use a 50 mm lens and enlarge by a factor of eight from 
the processed film to the screen, then you must view from a 
distance which is eight times the 50 mm which is 400 mm or about
16 inches.

Next, what lens you need:
Dr.T wants to view from 20" which is 500 mm.  You want to make
your on-screen images 2.5" wide and you do crop in the viewfinder.
2.5" is 63.5 mm which is 63.5/24 = 2.6X enlargement.  So the 
lenses you should use to satisfy Dr.T are 500/2.6 = 190 mm.
It's not that fussy so use a 180 or a 200.

Clear?

John B


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