[Leica] Any S2 experiences?

[henningw at archiphoto.com (Henning Wulff)]

At 11:08 AM +0100 3/21/10, philippe.amard wrote:
>Le 21 mars 10 ? 01:08, John Nebel a ?crit :
>
>>
>>  Philippe,
>>
>>  Rabs put it this way: "it's a medium format 
>>camera in a 35mm package. Delight in its 
>>deceptiveness."
>>
>>  S2 has an f/2.5 lens vs the M's f/1.4 (or 
>>f/1.0 or even f/.95) and is slower due to the 
>>larger image circle.  The S2 sensor is 45x30mm 
>>and the M's is 36x24mm.
>>
>>  Maybe it is not correct, but I was thinking of 
>>a projector as an analog, move it farther from 
>>the screen and the image is bigger, but darker. 
>>Twice the diagonal size, 1/4 the brightness as 
>>the lamp has to illuminate the equivalent of 
>>four of the original images.  Makes me think of 
>>the Meno.
>>
>
>80/2,8 = 40/1,4 = 28.5714
>
>you get different aperture (f) values, but the 
>amount of light is the same as the 'hole' is the 
>same, or am I completely mistaken in the 
>aperture calculation formula?
>
>http://fr.wikipedia.org/wiki/Ouverture_(photographie)
>
>I would bet that the absence of faster f value 
>on a MF/LF sensitive media lenses results from 
>other considerations such as angle and light 
>fall out in the outer parts of the 
>sheet/film/sensor.
>
>
>At the other end of the size spectrum, if we 
>take the Pana 4/3 pancake you'd get 20/1.7 = 
>11.7647 a smaller hole, hence slower speeds? 
>unless compensated by the electronics ? with 
>less fall-out issues?
>I really don't know.
>
>
>Thanks
>Philippe


If the hole is the same size (physical aperture, 
not relative aperture or f/ number) then the 
amount of light is the same, but the sensor/film 
is larger, and that amount of light is spread 
over a larger area so that's why the relative 
aperture is the one that makes sense, and is what 
we use.

Faster lenses on MF cameras don't exist because: 
on a 6x7 camera (approximately twice the linear 
magnification of 35mm) an f/1.4 normal lens would 
weigh about 6x as much, and would probably cost 
more by an even larger factor if it was 
approaching decent. Then there is the focussing 
and dof issue. Then there is the film flatness 
issue. So you would wind up with a 3kg, $10 to 
25k lens that you couldn't reliably focus and had 
insufficient dof. Not a big seller.

Your comments about m4/3 I don't understand. 
However, fast lenses in smaller formats have 
existed for a while, like the 13mm f/0.9 Switar 
for Bolex 8mm. It was a truly superb lens and it 
was for sale 50 years ago. 8mm movie film never 
produced crystal clarity, but that Switar was 
able to get the most out of it.

-- 

    *            Henning J. Wulff
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