[LargeFormat] Observation...

[Ole Tjugen]

>===== 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