[LargeFormat] Observation...
Ole Tjugen
largeformat@f32.net
Tue Feb 4 07:18:38 2003
>===== Original Message From "Richard Knoppow" <dickburk@ix.netcom.com> =====
<snip>
> There was a fairly wide choice of Tessar type lenses of
>f/4.5 aperature up to at least 12 inches. Goerz also made
>f/4x5 Dogmars to 12 inches, longer ones being f/5.5. B&L
>listed f/4.5 Tessars to 19-1/2 inches and Zeiss to 20
>inches. These must be impressive chunks of glass. The great
>speed was mostly to get limited depth of field for portrait
>work.
Ehrm... If you look at the previously mentioned photo of me handholding a 5x7
Technika, you can see how big a f/4.5 300mm (12in) Xenar is.
The main reasons for big, fast lenses (in 1910) were:
a) Ease of focus. Try focusing a f/16 lens in a candle-lit room. Remember that
flashbulbs (or flash powder) normally don't have modelling lights. If your
portrait subject is sharp enough at f/4.5, the picture will certainly be sharp
enough when you fire the flash at f/32!
b) Slow films. Dry plates were about as sensitive as modern enlarging paper.
When not using flash, large apertures were necessary to avoid the need for
mealbreaks during exposure ;)
Ole