Re: "normal" lenses, QH bulbs, Stemar

[P3D harold lee tichenor <hticheno@xxxxxxxxx>]

Eric Goldstein  <egoldste@xxxxxx> asked:

tell us why 50ish mm became the convention for "normal"
> lenses on 35 mm cameras...

I just got back in town and read the last twenty eight photo-3d editions!

The 50mm lens is the standard for 35 mm motion picture cameras. Oskar Barnack 
conceived of and designed the original Leica as an "exposure meter" for 
motion picture cinematographers in the 1920's! Leitz had already been 
building lenses for motion picture cameras and he appropriately chose a 
standard focal length lens for his prototype. 35mm motion pictures use 4 perf 
pull down for a standard frame; a motion picture standard 50mm was adapted to 
the 8 perf horizontal format of the new still cameras they produced. It is in 
fact a wide angle lens in this case if referenced against motion picture 
terminology. Vistavision, which is an eight perf motion picture format 
(called Lazy 8 because the magazines are mounted horizontally) utilizes 
standard focal lengths on the order of 85mm. 

I recently picked up a Sylvania BTP Quartz Halogen 750 watt lamp for my slide 
projector.  There does appear to be about a twenty to twenty five percent 
increase in light output and less heat at the slide!  I haven't measured 
this, but would be interested to hear from those with a probe type 
thermometer if there is in fact less heat at the slide. Perhaps because the 
lamp housing is smaller than the old projection lamp there is more air 
circulation room around the bulb allowing greater heat dispersal. After 
running for half an hour there appeared to be no effect on the bakelite bulb 
socket housing.  This is in a Prado 66 projector; I have no idea whether 
there would be problems with other projectors.

Yes it was my Stemar for sale at $7900; and yes I would give Jamie a deal if 
he asked, and no I am not abandoning the format for a Realist: I had a 
matched pair of these lenses from a research project I was involved in and am 
now done with the project and will only keep one for shooting. While I think 
the Stemar is a fantastic lens for a variety of reasons (excellent contrast 
and sharpness, field interchangeability with other lenses on the Leica M's 
allowing shooting 3d and standard 2d on the same roll in the same camera, 
18mm interocular allows near macro shooting as close as 21 inches while prism 
system provides for a 73mm interocular) it does have the drawbacks of being 
only four perf vertical format, leading to 7p envy and is ridiculously priced 
because of Leica collector pressure; I gather only a few hundred were made in 
1954. 

I spent six weeks on the road this Fall and shot with it across America 
including Mesa Verde and Hovenweep.  The resulting shots were very rewarding 
and its pocket size compactness was an asset while scrambling around near 
inaccessible ruins.

Regards
Harold


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