No matter what, only color film do. It gives more information on CA and
purple fringe, I don't think I can have a good judge with B/W.
C.H.Ling
----- Original Message -----
From: "Ken Norton"
> >
>> I don't understand shooting B&W and B&W, high contrast test charts if
>> you're ultimately going to be shooting color film and real world scenes.
>> You could probably save on film by first filtering the duds with the
>> digital. If the lens doesn't cut it in the center it's unlikely to do
>> much good in the corners.
>>
>
>
> Shooting the test charts in color is really only beneficial if you want to
> see the color aberations.
>
> If shooting in color, it would be preferable to use slide film for loupe
> analysis and the only current choices that I would consider for
> high-contrast tests is Ektachrome 64T, Kodachrome 64, or Fujichrome Astia
> 100F.
>
> The key to picking a film for lens testing is looking at the film's MTF
> Curves. Examine the 50% response point and see that it exceeds 30
> cycles/mm. (30 cycles/mm is about halfway between the 20 cycles/mm line
> and
> 50 cycles/mm line).
>
> If your tests are limited in contrast, Fujichrome Velvai 100 (not 50 or
> 100F) is the current leader with a MTF at 50% of around 50 cycles/mm,
> otherwise lateral halation will be the limiting factor. Portra 100F is
> among
> the worse films for lens testing because of this. If your contrast is
> reasonable in the test-chart, Fujichrome Velvia 100 would beat all.
>
> If color negative films would work, I'd use Kodak Portra 160NC or the
> newest
> Fuji 160S without hesitation. These are the finest-grain, highest
> resolution
> color print films on the market--with 160S being slightly higher
> resolutioned, but 160NC having less grain.
>
> We shoot res charts instead of "real world scenes" for lens tests because
> of
> controlled lighting and repeatability. It's too easy to be fooled by
> changes
> in exposure or contrast when shooting trees like Ken Rockwell does. You
> don't want to be a "Rockwell" now, do you?
>
> USAF line-pair charts may be "old school" but they existed for a reason
> and
> I personally haven't found anything more consistant and reliable for
> comparison testing.
>
> AG
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