Re: Bergger Versus Forte/ PMK testing.

From: Sandy King ^lt;[email protected]>
Date: 05/02/04-11:43:20 PM Z
Message-id: <a06020401bcbb89076248@[]>

I have also tested the three films produced at the plant in Hungary
(Bergger BPF 200, JandC Classic 200, and Fortepan 200) and in my
opinion they are one and the same. A 20% difference in density is not
all that significant since you will easily find that much difference
in films we know for sure to be the same. And of course the more
density you have, the more stain there will be.

The curve of a film tells you more and the curves of these films are
virtually identical except for some minor differences in emulsion
speed, which I attribute to conditions of storage, age, emulsion
batch, etc. But when you adjust the curves for density you find that
they are mirror images of one another, and all of the films have
virtually identical N expansion and contraction potential.

As far as I am concerned these films are the same duck since they
look and quack alike, even though one may quack a bit louder from
time to time.

Sandy King

> I can not remember whether it was in this forum that
>the question of whether these 200 speed films are the
>same was ask. Never the less I have done a side by side
>comparision, by my intial test it appears they are not.
> I shot both 120 rolls under identical conditions, controlled
>ambient daylight, metering from a centrally positioned
>grey card. Both films were processed using the Bergger suggested
>PMK time of 12 minutes, I processed both rolls in the same tank
>using 500ml of solution, dilution was 1+2+100 at 68F. I did add a pinch of
>amidol to increase the overall speed for both films.
> The end result, appears that Bergger produced both a denser
>and more highly stained roll of negatives. The difference is what I estimate
>to be approximately 20 %....for both stain and density.
> Perhaps as was stated by someone else the film is made at the same plant
>using Bergger's specification. The paper backing is the same, the film base
>appears the same,spools and paper tape the same.
Received on Sun May 2 23:45:17 2004

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