The exit pupil of a 400mm lens at 5.6 is 71.4mm, which is awful close to
the size of your filter, especially if you consider the amount of
material on the inside of the threads (probably more like 69mm or less
actuall glass diameter measured from the back side). You would most
likely get vignetting at 400.
Not sure about 100, but my guess is not. It isn't a very wide angle of
view and the exit pupil at 100/4.5 should be pretty small. 58mm filters
work with a lot of extra room on a 100/2.8. Are there flaws in my
filter logic here at the 100mm end?
Mike
Pierre Bellavance wrote:
>
> Hi,
>
> While I'm anxiously waiting for my two new babies (20/2.8 and
> 100-400/4.5-5.6L) I'm starting to think about filters.
>
> I already have a 72mm SMC Polarizer that will fit the 20/2.8.
>
> Maybe I should get a 77mm Polarizer ($$$) for the 100-400? Can I use the
> 72mm filter on this lens with an adapter? Maybe at 400mm but not at 100mm?
>
> I only shoot negative color film, and was wondering if I would need other
> filters for outdoors photography.
>
> I've heard of Gradual Neutral Density filters. Are they useful? Maybe for
> the wide angle lens?
>
> Thanks.
>
> Pierre
*
****
*******
***********************************************************
* For list instructions, including unsubscribe, see:
* http://www.a1.nl/phomepag/markerink/eos_list.htm
***********************************************************
