Re: SLIDE FORMAT OF 3-D CAMERAS

[michaelk@xxxxxxxxxxx (Michael Kersenbrock)]

> The square format is closer to circular and the field of view of an 
> ocular lens, at least the good part, is circular.  So to maximize view 
> area (measured  in steradians), you would want a circular format.  Next 

That seems reasonable if one is trying to squeeze the cost of designing
an optical system for the very lowest cost in conjunction with the goal of a
particular measured performance at the image's worse-case corner. 

On a system level, for those who project, screens tend to be square, so
a square format can provide a larger image on that screen.  Another advantage
for that format.

If one wanted equal performance for the middle 23x23 portion of the image
in either a 5-perf or 8-perf format, there doesn't seem to be any great
advantage.  The "bonus" area of the 8-perf film may have higher abberations
(with nothing else different), but  then, it's an area that the other 
format doesn't have at all.

If one has an 8-perf image, but the camera totally vignettes the left and 
right 1.5 perf portions, one ends up with the 5-perf image.  So, if one
"thinks square" when taking a photograph with a RBT camera, the images
could be then masked and mounted in a square format mount, and nobody is
the wiser.  One has the option to do this, or not.  Without optical loss
as would be the case in making an 8-perf format slide from a 5-perf 
original image.

Of course, costs don't always go the way one may expect.  If a camera 
company is manufacturing mass quantities of 8-perf format camera lenses
and shutters in highly automated production line, it may be cheaper 
to use an 8-perf design than to do a new design in some other format
and the design experience available may result in inferior quality.
Practicality in a design environment often doesn't justify an assumption
of "all other things being equal".  :-)

A bigger question is whether cost-performance is more important than
absolute technical performance.  Or further, where between
these extremes is the optimal compromise?  The answer isn't simple
because that point is different for each user/buyer.  Those who buy
RBT's are toward one end, while a weight-shifting Goodwill-purchased 
instamatic camara user may toward the other end.  In sheer cost/performance,
that $2 instamatic does pretty well (and probably in 8-perf format too)! 
Next step would be to have two of those ($4) and twin them.

Mike K.


P.S. - I'm surprised that I haven't seen any grumblings about the new APS
       (seemingly) print-only format.  Should we beamsplit one camera or
       siamese-twin two of these reportedly small cameras?  (We'll continue
       this after this commercial break from Nabisco.....image fades out...).  


P.P.S. - I use 5-perf format 95% of the time (an unmentionable 4-perf format
         used under certain circumstances for the other 5%), but am very impressed
         by full-frame and European formats when I see them (as well as dual
         medium-format, but I haven't seen that projected yet).






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