[Leica] How fast is the human eye?

[tedgrant at shaw.ca (tedgrant at shaw.ca)]

ANSWER:

On most of my indoor assignments the norm ASA is 800. That's just a one stop 
push from the normal film ASA 400.

On occasion I use 1600, but only if necessary. For high action indoor sports 
I just spin up 3200 and never worry about anything!

Dr. ted
----- Original Message ----- 
From: <lrzeitlin at aol.com>
To: <lug at leica-users.org>
Sent: Thursday, October 22, 2009 2:59 PM
Subject: [Leica] How fast is the human eye?


> 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
>
> _______________________________________________
> Leica Users Group.
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