From: Sandy King (sanking@CLEMSON.EDU)
Date: 10/31/02-10:48:49 AM Z
Tom wrote:
>
>
>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.
As I recall much of your work is in the studio. What type of lighting
are you using and are you working at the low end (1-4 seconds) of
reciprocity or at the high end (30+ seconds).
> Also remember that that extra 90 seconds sounds huge (your 200
>versus 290seconds example). But, it is really only a 1/2 stop
>difference.
Actually, since the effects of reciprocity increase exponentially and
not linearly with increasing time, the effective difference between
200 and 290 seconds is most likely much less than the nominal 1/2
stop difference which is suggested by the two different times,
perhaps no greater than 1/8 of a stop.
Sandy King
>
>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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