Re: cyanotype question

Hmmm. Actually the effect is beginning to make sense to me based on
what you've just said. The 2 step gain is on the low end while the
higher zones are not increasing as much. The lower densities'
transmissions are closer to 100% so an arithmatic unit increase in
exposure would have a relatively greater effect there than on the high
zones. In other words, if max density is reached on step 1 which has a
density of approximately 0.00 an additional 250 units would really flood
the adjacent steps with exposure effect. At the same time, step 13
transmits only about 1.5% so it would require a huge arithmetic increase
to make a geometric increase of 2 steps (1 stop density) at that point.
Part of the exposure effect is also probably masked by the printed out
image in both the low steps and higher ones, but more pronounced at the
lower end. Add to this a possible intermittency effect as well as a
dark or drying effect. I don't think I would be able to isolate the
variables enough to actully solve this dilemma.

It really makes me see why the density range of the negative becomes so
important and why the negative density range needs to be tailored to a
specific process and set of materials. I guess the easiest conclusion
is that an additional unit of exposure isn't just going to shift the
scale along the stepwedge evenly (as I assumed earlier) and the degree
to which this is evident actually depends on where the unit print
exposure matches the overall negative density scale.

I think I'll give this a rest now and fine tune a couple prints. I'll
post the images somewhere along with the stepwedges in a few days if
anyone is interested.

Joe

>>> Ender100@aol.com 09/03/04 10:13 AM >>>
Joe,

That's what is sort of baffling.... two steps is equal to a full stop,
or
doubling the exposure. So you should go up 2 steps when you double the
time
from 250 units to 500 units....and that is indeed what happened.
However, you
reported that you got two more steps merging when you went from 500 to
750
units..... that should have only happened if you doubled the time from
500 units to
1000 units.

Mark Nelson
www.precisiondigitalnegatives.com
www.markinelsonphoto.com

In a message dated 9/2/04 10:19:17 PM, jsmigiel@kvcc.edu writes:

>
> Yes. You have it right as far as the mergers are concerned but I
don't
> follow you on the question about 2 additional steps merging at 750
units. No
> steps merge at 250. Three steps merge at 500 which indicates the low
end was
> pushed up the scale 2 steps as an additional 250 units was given. The
same
> thing happened as the exposure was further increased by 250 units to
750, i.e.,
> the low end was pushed up the scale another 2 steps. This is also
showing in
> how many steps solarized initially. The highest solarized steps were
6, 8,
> and 10 for the 250, 500, and 750 unit exposures, respectively. The
low steps
> are acting in a consistent manner gaining 2 steps with each additional
250
> unit exposure. It is the high end that is behaving strangely showing
a
> decrease in the rate that the tones print as exposure is increased.
>
Received on Sun Sep 5 08:23:59 2004