[pure-silver] Re: multigrade paper is amazing
- From: "Nicholas O. Lindan" <nolindan@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Thu, 8 Nov 2007 14:22:31 -0500
"Shannon Stoney" <shannonstoney@xxxxxxxxxxxxxxx>
I just did an interesting experiment. I printed a stouffer step tablet
on Ilford warmtone multigrade paper, beginning at #00 filtration and
ending at #5 filtration. I found out that the paper scale varies not a
little bit, but a whole lot!
http://www.darkroomautomation.com/support/mgivfbwt-zone.jpg
http://www.darkroomautomation.com/support/mgivfbwt-hd.jpg
But it is a very good exercise. At some photography school(s) (RIT?)
a whole semester is dedicated to imaging a step tablet. After that
they let the students handle a camera.
After printing the step tablet, I read its values on a densitometer. I
found out that at filtration #00, the paper has a scale of 1.5. It
printed about 12-13 steps between say zone 3 and zone 7. On the other
hand, at filtration #5, it had a scale of only 0.47 and printed only
4-5 steps between zone 3 and zone 7.
Grade 00 is abut 6 stops toe to shoulder [and a pretty funky
shoulder it is].
Grade 5 is 1.8 stops toe to shoulder.
The number of densities between toe and shoulder is infinite in each
case.
The number of zones is 10 - '0' to 'IX' in each case - by the
definition of a zone. See AA.
The number of 'steps' depends on the step tablet: 0.1 OD, 0.3OD,
0.5 OD intervals are common in commercial tablets.
A step tablet doesn't even have to have equal intervals between
steps. All it needs is a set of known densities. You can make
a perfectly serviceable step tablet yourself.
A very useful uneven-step tablet is a tablet of zones.
==
Nicholas O. Lindan
Cleveland Engineering Design, LLC
Cleveland, Ohio 44121
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