[Leica] WTB : Noctilux (UK)

[alal at duke.poly.edu (A. Lal)]

Actually a 35/1.4 gathers less light than a 50/1.4. Remember, the light 
gathering ability depends on the absolute aperture. The absolute aperture, D 
=  (focal length)/(f- number), assuming non retrofocus construction.

For a given exposure the brightness of an image of an extended object 
depends on  the number of photons per unit area, while for a point object 
the image brightness depends on the total number of photons.

Thus, if you are photographing a normal scene, similar f- (actually, T- ) 
stops will give similar exposures, irrespective of the focal length. On the 
other hand, when taking photos of point sources like stars, the absolute 
aperture counts. Thus, a 180 mm f/2.8 lens will image fainter stars than a 
50mm/1.4 lens.


> On 1/1/07 02:19, "Tina Manley" <images@InfoAve.Net> wrote:
>
> Frank - I was referring to the 35/1.4 and the Noctilux 1.0 - just that the
> 35 is wider and encompasses more light
>
>
>