Contact Printing: How Black To Go?

How do I determine what is "black enough" on a contact print? I've done an
exposure test strip 5, 10, 15, 20, 25, 30 secs. and have determine there is
just a smidge of discernable difference between 20 and 25 and no difference
(that I can see anyway) between 25 and 30 I think. New Dektol. Silver Paper.
I'm trying to build a curve to apply to my digital negatives. My thinking is
that I have to establish my enlarger time first because it shouldn't be a
variable. Then build the curve from my step wedge. I could probably get away
with 15-20 seconds because that was an OK black. What's the thinking on
this?

Alan Smithee wrote:
How do I determine what is "black enough" on a contact print? I've done an
exposure test strip 5, 10, 15, 20, 25, 30 secs. and have determine there is
just a smidge of discernable difference between 20 and 25 and no difference
(that I can see anyway) between 25 and 30 I think. New Dektol. Silver Paper.
I'm trying to build a curve to apply to my digital negatives. My thinking is
that I have to establish my enlarger time first because it shouldn't be a
variable. Then build the curve from my step wedge. I could probably get away
with 15-20 seconds because that was an OK black. What's the thinking on
this?


What I do projection print a step wedge that goes from 0 (actually 0.06)
gross density up to about 3.15 (IIRC) and my usual time, height, and
aperture. I process this normally and when dry, examine it under a light
somewhat stronger than normal (but not ridiculously strong). I look for
the last step that I can distinguish from the darker ones. The next one
is, for me, maximum black.

Now my "reflection densitometer" is that Kodak Densiguide, Q-something,
with holes in it. By that standard, this black has a reflectioin density
greater than 2.0.

Now for making negatives, since printing step wedges gets old very fast, I
print so that the clear edge of the negative matches that maximum black.
Now the first time I tried that, the rest of the print was way too dark.
But to get maximum black, I _must_ expose the negative at least that long.
Since the contrast index was correct, the only way to manage is to expose
the negative more in the camera so that the mid tones come out right. That
way, the clearest parts of the negative _will_ print maximum black, the
midtones will look "right" (i.e., what I expose for Zone V will, when
printed, match the 18% gray card), and the highlights will be right too
(if the contrast index was correct).

The only thing that might be unexpected is that the net densities for Zone
I come out around 0.25 to 0.3 instead of the 0.1 Ansel Adams recommended
in his books. So what?

--
.~. Jean-David Beyer Registered Linux User 85642.
/V\ Registered Machine 241939.
/( )\ Shrewsbury, New Jersey http://counter.li.org
^^-^^ 14:55:00 up 4 days, 16:47, 3 users, load average: 4.21, 4.15, 4.05

Alan Smithee wrote:
How do I determine what is "black enough" on a contact print? I've done an
exposure test strip 5, 10, 15, 20, 25, 30 secs. and have determine there is
just a smidge of discernable difference between 20 and 25 and no difference
(that I can see anyway) between 25 and 30 I think. New Dektol. Silver Paper.
I'm trying to build a curve to apply to my digital negatives. My thinking is
that I have to establish my enlarger time first because it shouldn't be a
variable. Then build the curve from my step wedge. I could probably get away
with 15-20 seconds because that was an OK black. What's the thinking on
this?


What I do projection print a step wedge that goes from 0 (actually 0.06)
gross density up to about 3.15 (IIRC) and my usual time, height, and
aperture. I process this normally and when dry, examine it under a light
somewhat stronger than normal (but not ridiculously strong). I look for
the last step that I can distinguish from the darker ones. The next one
is, for me, maximum black.

Now my "reflection densitometer" is that Kodak Densiguide, Q-something,
with holes in it. By that standard, this black has a reflectioin density
greater than 2.0.

Now for making negatives, since printing step wedges gets old very fast, I
print so that the clear edge of the negative matches that maximum black.
Now the first time I tried that, the rest of the print was way too dark.
But to get maximum black, I _must_ expose the negative at least that long.
Since the contrast index was correct, the only way to manage is to expose
the negative more in the camera so that the mid tones come out right. That
way, the clearest parts of the negative _will_ print maximum black, the
midtones will look "right" (i.e., what I expose for Zone V will, when
printed, match the 18% gray card), and the highlights will be right too
(if the contrast index was correct).

The only thing that might be unexpected is that the net densities for Zone
I come out around 0.25 to 0.3 instead of the 0.1 Ansel Adams recommended
in his books. So what?

--
.~. Jean-David Beyer Registered Linux User 85642.
/V\ Registered Machine 241939.
/( )\ Shrewsbury, New Jersey http://counter.li.org
^^-^^ 14:55:00 up 4 days, 16:47, 3 users, load average: 4.21, 4.15, 4.05

"Alan Smithee" wrote in message news:mzRfd.43670$Pl.20272@pd7tw1no...
How do I determine what is "black enough" on a contact print? I've done an
exposure test strip 5, 10, 15, 20, 25, 30 secs. and have determine there is
just a smidge of discernable difference between 20 and 25 and no difference
(that I can see anyway) between 25 and 30 I think. New Dektol. Silver Paper.
I'm trying to build a curve to apply to my digital negatives. My thinking is
that I have to establish my enlarger time first because it shouldn't be a
variable. Then build the curve from my step wedge. I could probably get away
with 15-20 seconds because that was an OK black. What's the thinking on
this?

What are you talking about?

The question is mostly geek speak to me. However, I will tell you how I
(chemicals only) determine the correct exposure for a contact sheet.
I run a test strip, but NOT of the pictures! I run a test strip across all
the negative strips in a holder and I make sure that each of the sprocket
strips are exposed for progressively longer amounts of time. Then I examine
each strip to determine what amount of exposure causes the sprocket holes to
become so dark that can no longer be distinguished (just) from the strips
between them. That is the "correct" exposure for the entire contact sheet,
and I think it will produce the best overall result.

"Uranium Committee" wrote in message
om...
"Alan Smithee" wrote in message
news:mzRfd.43670$Pl.20272@pd7tw1no...
How do I determine what is "black enough" on a contact print? I've done
an
exposure test strip 5, 10, 15, 20, 25, 30 secs. and have determine there
is
just a smidge of discernable difference between 20 and 25 and no
difference
(that I can see anyway) between 25 and 30 I think. New Dektol. Silver
Paper.
I'm trying to build a curve to apply to my digital negatives. My thinking
is
that I have to establish my enlarger time first because it shouldn't be a
variable. Then build the curve from my step wedge. I could probably get
away
with 15-20 seconds because that was an OK black. What's the thinking on
this?

What are you talking about?

"Mike Schuler" wrote in message
om...
Although this makes some sense, since you are rescanning the print
your scanner's 'curve' is also being applied, the rest or your process
will be biased, won't it? If your final output is a chemical print,
it seems to me that you should do the analysis there, either visually
or with a densitometer.

At first sight one would expect the scanner's "curve," or any CCD's "curve,"
to be a straight line. But postprocessing may be going on in the software
which would alter that.

"Alan Smithee" wrote

The original question was to ascertain what people considered
an acceptable method for determining how "black" a perfect black
should be in a print, why and what's the best method to use.
I'm new at this darkroom thing, but not at this computer
thing...cheers. Thx.


I've looked at scores of prints evaluating black vs black; step
tablet and fb+f. As you pointed out there is black and then there
is black.
The very blackest will perhaps pull all print values too dark.
That very black may be one or two stops more exposure than needed
to produce a black only faintly less dark.
Print papers vary in their max black. Developers can influence
to a small degree final maximum density and of course toners.
I'd say it is a subjective call in practice. Prints given
a little of a high-key finish may have less dense blacks.
Life may not be so simple. Dan

"Alan Smithee" wrote

The original question was to ascertain what people considered
an acceptable method for determining how "black" a perfect black
should be in a print, why and what's the best method to use.
I'm new at this darkroom thing, but not at this computer
thing...cheers. Thx.


I've looked at scores of prints evaluating black vs black; step
tablet and fb+f. As you pointed out there is black and then there
is black.
The very blackest will perhaps pull all print values too dark.
That very black may be one or two stops more exposure than needed
to produce a black only faintly less dark.
Print papers vary in their max black. Developers can influence
to a small degree final maximum density and of course toners.
I'd say it is a subjective call in practice. Prints given
a little of a high-key finish may have less dense blacks.
Life may not be so simple. Dan

Dan Quinn wrote (in part):
"Alan Smithee" wrote

The original question was to ascertain what people considered
an acceptable method for determining how "black" a perfect black
should be in a print, why and what's the best method to use.
I'm new at this darkroom thing, but not at this computer
thing...cheers. Thx.



I've looked at scores of prints evaluating black vs black; step
tablet and fb+f. As you pointed out there is black and then there
is black.
The very blackest will perhaps pull all print values too dark.

Usually does with typically exposed negatives, but as I have posted
previously, you can correct that, without affecting your contrast, by
exposing your negatives more (usually one stop more is enough) so that
Zone V on the negatives come out with a net density of about 0.85 to 0.9.

That very black may be one or two stops more exposure than needed
to produce a black only faintly less dark.


--
.~. Jean-David Beyer Registered Linux User 85642.
/V\ Registered Machine 241939.
/( )\ Shrewsbury, New Jersey http://counter.li.org
^^-^^ 17:35:00 up 5 days, 19:27, 4 users, load average: 5.92, 5.77, 5.14

Dan Quinn wrote (in part):
"Alan Smithee" wrote

The original question was to ascertain what people considered
an acceptable method for determining how "black" a perfect black
should be in a print, why and what's the best method to use.
I'm new at this darkroom thing, but not at this computer
thing...cheers. Thx.



I've looked at scores of prints evaluating black vs black; step
tablet and fb+f. As you pointed out there is black and then there
is black.
The very blackest will perhaps pull all print values too dark.

Usually does with typically exposed negatives, but as I have posted
previously, you can correct that, without affecting your contrast, by
exposing your negatives more (usually one stop more is enough) so that
Zone V on the negatives come out with a net density of about 0.85 to 0.9.

That very black may be one or two stops more exposure than needed
to produce a black only faintly less dark.


--
.~. Jean-David Beyer Registered Linux User 85642.
/V\ Registered Machine 241939.
/( )\ Shrewsbury, New Jersey http://counter.li.org
^^-^^ 17:35:00 up 5 days, 19:27, 4 users, load average: 5.92, 5.77, 5.14