Archived posting to the Leica Users Group, 2000/09/24

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Subject: Re: [Leica] printing questions
From: Mike Quinn <mlquinn@san.rr.com>
Date: Sun, 24 Sep 2000 18:36:25 -0700

Guy,

I've always used a similar system based on the fact that the change in
intensity of light falling on the paper is inversely proportional to the
change in magnification.

The problem with the formula below is that w1 and w2 should be measured from
the widths of your negative (or negative mask) projected on the easel rather
than the width of your print. Any size print that falls within the
negative's projected light will require the same exposure regardless of the
width of the print.

I usually find it easier to measure H1 and H2 where H = the height of the
negative above the easel (shown on my enlarger column).  In either case
H1/H2 = w1/w2 = the change in magnification.

Mike Quinn

Guy Bennett wrote:

> the next question is related, and it concerns the extrapolation of new
> printing times when making another, different-size print of a given
> negative. he offers the following equation for making the calculation: t2 =
> t1 x (w2/w1)2 [i.e. squared], where t2 = new initial exposure, w2 = new
> print width, t1 = initial time of the original print, w1 = width of the
> original print. my question: do any of you use this, or any other system to
> extrapolate new print times for enlargements? is such a system reliable,
> given the variables involved (different batch of paper/new chemicals/etc.)?