Re: [Leica] AGFA APX400

[Johnny Deadman <john@pinkheadedbug.com>]

on 9/22/01 1:22 AM, Guy Bennett at gbennett@lainet.com wrote:

>> I've read that APX400 better when rated at 320 ASA, instead of it's
>> native 400ASA. Anything to this? Anyone tried it? Am I the last person
>> on the planet shooting AGFA B/W?
>> 
>> feli
> 
> 
> Agfa 400 is my main film. I always and only rate it at 400. If I need
> something faster, I go for Fuji Neopan 1600 or Delta 3200. If I need
> something slower (and I haven't yet), I'll probably use Delta 100.

what Guy said. I rate APX400 at exactly 400 ISO and it hasn't failed me yet.
For ISO 100 I use either Delta 100 or APX 100.

As Mark R pointed out in a previous post, the speed you rate a film at
should NOT be a matter of guesswork and 'hm I'll try this'. You should run a
test roll of film exposing at different speeds (eg one-third stop intervals
between 200 and 800 in this case) and develop in your standard soup for the
standard time. Then look at the negs. The highest speed in which you get
proper shadow detail (this means Zone III has full details but Zone II
doesn't, as per THE NEGATIVE) is the speed you should use.
You then tweak your development times to get the contrast (highlights)
right.

If you're not a zonie, I'll put it another way. Choose your test scene and
meter it as you would normally (VERY important to do this just as you always
do since the technique gets incorporated into your personal film speed).

Now find some part of the scene which meters TWO STOPS BELOW this reading.
IE some shadow or dark material. This is the crucial area to examine in the
negative. You are looking for the *maximum* film speed which gives you
*full* detail in this area, which is your important shadow detail.

Make your exposures at the different film speeds, develop, and put the negs
on a light box. Starting with the negs which are too thin, move along the
strip towards the negs that are too thick. The first neg where you can see
full detail in the dark part of the scene gives you the ISO you should use.

(You can make prints if you like to double check but I think it is easier to
see this stuff on the neg).

What if this negative looks too thin, or too flat, or too dense? You now
know that this is NOT a function of exposure but of development, and can
tweak the time in the soup accordingly until your highlights are right.

This seems boring but you only have to do it once and there's no guesswork
involved. I did it nearly 3 years ago for APX/Xtol and haven't second
guessed myself since.

In my own case, I find that APX in Xtol 1:1 has a true speed of around 4-500
ISO. In Xtol 1:3 it is somewhat higher at around 600 ISO but it's okay to
use 400 because the compensating effect of the developer keeps the
highlights nice and smooth. DO NOT use my numbers! The way I meter and
develop may be *totally* different to the way you do, which will screw you
up completely. For example, I may unconsciously meter the shadows and you
may unconsciously meter the highlights. If this is the case we *should* be
rating the film at very different speeds.
- -- 
John Brownlow

http://www.pinkheadedbug.com

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