Re: reciprocity failure chart failure

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From: Tom Ferguson (tomf2468@pipeline.com)
Date: 11/01/02-09:05:11 AM Z


On Thursday, October 31, 2002, at 08:48 AM, Sandy King wrote:

> 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).

Both. When shooting for silver gelatin using the 4x5 camera I'm often at
the "low end (1-4 seconds), when shooting with the 8x10 or 11x14 for alt
I'm usually at the "high end (30+ seconds)". For my own personal work I
prefer hot lights over strobes. Perhaps it "feels" too much like a
commercial shot with strobes??

>
>
>> 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.

A good and correct point. My 1/2 stop comment was overstated!


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