From: Bill Collins (photo@intrex.net)
Date: 10/31/02-12:00:27 PM Z
I wish someone made a black and white film with the reciprocity characteristics of the newer color slide films. I think the latest Provia needs no correction at 100 seconds!
Bill
---------- Original Message ----------------------------------
From: Tom Ferguson <tomf2468@pipeline.com>
Reply-to: alt-photo-process-l@sask.usask.ca
Date: Thu, 31 Oct 2002 08:23:17 -0800
>In my experience what you are seeing is the unpredicatble (batch to
>batch) variation in extreme reciprocity numbers. One "batch" of film "X"
>will be nearly identical to another batch at 1, 2, 4 seconds. Beyond
>that you get move variation.
>
>Simmons errors on the side of too much exposure. Make sense for silver
>gelatin work. But we are usually over developing our film and then
>giving annoyingly long UV exposures. A "too much" exposure neg can be
>real dense and slow to print :-(
>
>For my own work with T-Max 400 and HP5 for alt I find Simmon's a little
>too much and the manufacturer's a little too little. I split the
>difference. Also remember that that extra 90 seconds sounds huge (your
>200 versus 290seconds example). But, it is really only a 1/2 stop
>difference.
>
>On Thursday, October 31, 2002, at 07:21 AM, Shannon Stoney wrote:
>
>>> Shannon wrote:
>>>
>>>> Sandy wrote:
>>>>
>>>>> There is a reciprocity correction chart for Kodak, Agfa, Ilford and
>>>>> Polaroid B&W films on p. 75 of Simmon's Using the View Camera.
>>>>> Nothing on Fuji.
>>>>
>>>>
>>>> This chart gives even longer times than the Kodak online chart does.
>>>> So I assume if I had used it, my negatives would have been even more
>>>> overexposed! At least, at the higher end of the scale. At the lower
>>>> end, they're about the same.
>>>>
>>>> --shannon
>>>
>>>
>>>
>>> Overexposure takes place in the camera. If your negatives have a very
>>> high density reading at the lower end of the scale you gave too much
>>> exposure when exposing. CI or DR is controlled by time of development.
>>> We normally develop to get the appropriate density range for our
>>> process, and the low values just have to fall where they will.
>>
>>
>> Whoops, I wasn't clear here. What I meant was, the two charts
>> (Simmons' and Kodak's) give about the same adjusted times when they are
>> talking about 2 second or four second meter readings. When you get up
>> to say thirty seconds, the Simmons chart gives 290 seconds for the
>> correct exposure, whereas the Kodak chart says 200. That's a big
>> difference.
>>
>> --shannon
>>
>
>
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