Re: Aperture/shutter conversions

[P3D Dr. George A. Themelis <fj834@xxxxxxxxxxxxxxxxxxxxx>]

>Friends,
>This past week I shot up a roll of Kodachrome 64 around Dallas, TX (Dealey
>Plaza, HardRock Cafe, etc.).  To use the exposure table, I had to make
>conversions for the shutter and aperature.  Thought I'd pass along for others
>to use and/or refine.
>
>My Realist 3.5 has shutter speeds 150, 100, 50, etc. while the table on the
>film carton lists for t = 1/125.  Sooo, I developed the following formula,
>based on the formula that doubling the f-stop value produces a 2 stop (4x)
>decrease in exposure.

[good math stuff deleted]

>If you're picky, you can calculate a conversion table.  Or, you can simply
>open 1/5 stop (for t=1/150) or close 1/4 stop (for t=1/100), from the values
>given for t=1/125.  Of course, with the itsy-bitsy dial on a Realist, I can't
>be real precise.  But thank goodness, I don't have to be.

Can you please be a bit more specific here?  Why don't YOU have to be while
I, for instance, might have to be?  If you don't have to be "real precise"
why did you go though the excercise of calculating these 1/5 of an f-stop
corrections?   Do you honestly believe that 1/4 and 1/5 f-stop changes can
make any difference for anyone, considering other "real world" concerns?

-- George Themelis, going through a rough week...


------------------------------