From: edmtl@alf.uib.no (Thor Legvold)
Subject: Re: Different Films and Pro rated speeds ?
Organization: University of Bergen, Norway
Date: Mon, 14 Sep 92 12:04:23 GMT

In article <470@cimsand.UUCP> rune@cimsand.UUCP (Rune Riisnaes) writes:
>drinkard@icelan.enet.dec.com (Rich Drinkard) writes:
>: 
>: Does a list exist anywhere of the different (common anyway) films and the ISO
>: ratings the pro's use to shoot with them.
>: 
>: I would be interested in finding out.
>: 
>
>The rated speed, +- 1 stop :-)
>Seriously, this probably depends on a number of things, like personal
>preference, your subject, the development process at your lab, your printing 
>process, etc.   
>
>The films I use most are Velvia exposed at 40 ISO, and Reala at its rated 
>speed of 100.  (and I'm not a pro :-)

Excuse me for asking, but isn't Reala rated at 160???  I'm pretty sure it
was last time I used it (it _has_ been a few months ;-)

>
>An interesting question:  Most photographers I know, prefer to shoot Velvia
>at a lower ISO than rated.  If this is a common trend, what are the criterias
>Fuji (and Kodak for that matter) uses to determine a films rating.
>Is it purely technical, like density, color saturation, and such ?

There was a thread on this just last week.  Someone said that the criteria
and E-6 process as defined by Fuji differed from Kodaks, resulting in
'correct' exposure for Velvia at 50 in Fuji spec E-6, while Kodaks (which
specifies less agitation) required exposure at 40 to get the same results.
Of course when I asked the labs I use (both Fuji & Kodak) they said the 
whole point of a standard E-6 prosess was that it is standard - all brands
at all places (sound familiar? ;-) and that this 'info' was wrong.  Myself,
I expose at 50, which usually is perfect, in my opinion - when it gets'
shown on the screen it usually becomes a bit lighter anyway (BTW, I use 6x6)
I have tried (only a few) rolls at both 40 & 50 in a reasonably controlled
attempt to determine a difference.  There was one, but it was _very_
subtle.  It also depends on lighting.  On a cloudy (low contrast) day,
I don't think there is any difference, and I can't adjust my camera in 1/6th
stop increments from 50 to 40 ASA (according to the meter).  It seems like 
on bright days (high contrast) however that the difference between 40 & 50
becomes much more apparent - especially in shadow/dark areas.
I'll be testing a few more rolls (hey - it's sunny in Bergen today - 
I'll see if my 'theory' is correct ;-) and will try to remember to post 
the results.

I also wonder if anyone uses Velvia for portraits, and with what filter
(82b?) - I always seem to get a red shift.  What do 'pro's' use for 
positive portraits (I use Reala for negative portraits)???

>
>When Kodak changed the ratings of its Ektar film from 125 to 100, was
>that caused by a change in the film itself, or as a result of the way it
>was being used ?   
>Does anyone know ?

No.  Sorry.

>-- 
>Rune Riisnaes    E-mail: rune@cimage.no, rune@cimage.com, rune@cimsand.uucp
>                 Cimage A.S,  Skytterdalen 6,  N-1300 Sandvika,  Norway.
>                 Phone: (47-2) 54 90 40   Fax: (47-2) 54 58 40

Regards,
Thor
University of Bergen
Norway
edmtl@fiol.uib.no

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