maofd

[T3D john bercovitz <bercov@xxxxxxxxxxx>]

I was recommending the maofd spreadsheet earlier today for 
calculating the maximum stereobase.  It has been tested for that 
use and is good.  Several functions have been added and we might 
argue about whether they are realistically calculated or not.  
The calculation of the f/stop should be considered somewhat 
experimental at this point.  I would like to test it by taking 
photos before I can say it's a sure thing.  Certainly the 
calculations are appropriate approximations but I'm not sure if 
they give a result that suggests an f/stop that is within 0.1 or 1 
f/stop of exact.  So take that output with a grain of salt for 
now.  Again, the spreadsheet is available from:

ftp://bobcat.etsu.edu/pub/photo/photo-3d/technical/maofd/

Download the spreadsheet and the instructions.

To be _really_ specific, in case anyone would care to comment, 
the things that are suspect on precision are:
1) Having the lens + film resolution a constant - we know lens 
resolution varies according to the f/stop not just because of 
geometric and physical optics but also because of aberrations.  
So this is an approximation.  Is it good enough?
2) Setting the fuzziness due to geometric optics equal to the 
fuzziness from physical optics.  Does this really find us the 
minimum spot size and thereby the best f/stop?
3) Summing all of the resolutions in quadrature.  This is a fair 
approximation in my estimation but is it good enough?

All the rest of the outputs are either from book formulas or from 
simple geometry so I don't worry about the accuracy of them.  
Really, all the questions are about the f/stop and the accuracy of 
the approximations that calculate it.

John B


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End of TECH3D Digest 29
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