Re: Exposure

[Randy Little <randyslittle@xxxxxxxxx>]

No that part I get. But i am of the understanding that the amount of failure is equal across the entire frame because of the relationship of the shutter and aperture iris. 

On Apr 2, 2014 12:02 AM, "Andrew Davidhazy" <andpph@xxxxxxx> wrote:

Randy,

The blades uncover the whole (set) aperture faster when the diaphragm is set to a small aperture so

effectively the shutter delivers a longer exposure time (vs. the one it is assumed it is delivering). Because

the blades reach fully open position faster from the "midpoint" to the peak one would expect a bit of 

underexposure when the lens is set to a large aperture. 

Another way of saying this: if the diaphragm is set to f/22 the amount of light that f/22 allows to pass 

is available for a longer time than that which is allowed to pass when the diaphragm is set to f/4 for example.

And the full amount that f/2 for example passes is available for a shorter time than that which f/4 passes.

But the discrepancy at the high end tends to be a bit less "problematic" than at the low end where an error 

of maybe 1/2 stop or more can be experienced.

Anyone care to elucidate us further?

Andy

On Apr 1, 2014, at 11:40 PM, Randy Little wrote:

Andy dont they over expose equally though because of the relation of the cone and the aperture?