[Leica] How fast is the human eye?

[mark at rabinergroup.com (Mark Rabiner)]

> Mark writes:
> 
> It would be interesting to find out what the average iso the average
> 
> 
> photojournist is out there using right now I have no idea.
> 
> 
> Seldom have I ever done a shoot in which I didn't wish I could be shooting
> 
> 
> at a faster shutter speed and or stopping down one or two more.
> 
> - - - - - 
> Another interesting question is "How fast is the human eye?" If you can't 
> see
> a scene, does it really exist? Rather than being an exercise in the
> phenomenological philosophies of Berkeley and Hume, one could well take the
> position that shooting pictures of the invisible is out of the main stream 
> of
> normal photography. Philosophy aside, and despite the fact that the eye has
> been compared to a camera, there is very little in the scientific 
> literature
> that directly compares the sensitivity of the retina to that of film or a 
> CCD.
> So here is my guess. I pulled my trusty decades old GE meter from a drawer.
> With the hood off, the meter basically displays light intensity in foot
> candles. I know that photopic vision, the type mediated by the cones in the
> eye and lets you see fine detail and color, works well down to one 
> footcandle.
> A normal eye has an approximate f stop of 3.5 and has an integrating 
> function
> of 1/12 second. This could roughly be compared to the shutter speed. So 
> all I
>   had to do was set the meter dial to one footcandle, the shutter speed to
> 1/12 second, and the f value to 3.5 and read off the film speed necessary 
> to
> get a well exposed picture. It comes out to an ISO value of approximately 
> 800.
> So a camera with an ISO of 100,000 is 7 or 8 f stops faster than the human
> eye. That is enough to take fully exposed photos on a cloudy moonlight 
> night,
> or perhaps even bright starlight. I can't wait to shoot pictures of black 
> cats
> in a coal cellar.
> Larry Z


Larry its not the invisible that I'm so interested in although this is very
intersecting to me what you've written here.
What concerns me is the visible.
When I've visibly not gotten the shot because its really just too soft.
I've missed my focus I should have stopped down another stop or two.
I've got too much camera motion or subject motion in a shot so its just too
darned soft and I cant pass it off as a viable shot.

Right now the ISO's I'm able to use 800 and 1600 is many stops below what
the average photographer is out there able to use. So I need to get my act
in gear.


Mark William Rabiner