color printing - low contrast
Alexander Miller
much contrast as from commercial labs. Sometimes this is an advantage but often
not. I use a chromega enlarger & dichroic head with Nikkor lenses, Kodak supra
paper & Kodak RA-4 chemistry. Developing is in drum on a roller: 1 minute at
about 96 deg average. Extra time doesn't seem to make a perceptible difference.
I buy 3 gallon kits & make up a gallon at a time, keep it in airtight wineskins
to be drawn off & used to replenish my working stock, which lives in a one
litre container kept full & capped. I replenish developer & blix at 20ml per
8x10.
Anyone know why I don't get "commercial" contrast?.....The single package of
higher-contrast Ultra paper I tried has a cyan cast even on the white borders,
as well as needing what seemed like an excessive cyan filtration to get half
decent color balance, so I don't use it. Any comments??
I've also been plagued from time to time by the magenta/blue "tidemark" that
someone referred to here a while back. I've found that I can usually control it
by having neither too much nor too little chemistry in the drum: Checked it out
using saran wrap taped over ends of the drum so I could see how things went.
Also drum must be level when adding chemistry. If you have a wave-action roller
put reference marks on eccentric wheels when drum's in level position: Always
bring wheel to that position before adding chemistry.
BUT I never found out which processing step produces the stain; or why, really.
Anybody know? -Alexander
Barry Sherman
>I have been color printing for many years, but notice my prints never have as
>much contrast as from commercial labs. Sometimes this is an advantage but often
>not. I use a chromega enlarger & dichroic head with Nikkor lenses, Kodak supra
>paper & Kodak RA-4 chemistry. Developing is in drum on a roller: 1 minute at
>about 96 deg average. Extra time doesn't seem to make a perceptible difference.
>I buy 3 gallon kits & make up a gallon at a time, keep it in airtight wineskins
>to be drawn off & used to replenish my working stock, which lives in a one
>litre container kept full & capped. I replenish developer & blix at 20ml per
>8x10.
>
>Anyone know why I don't get "commercial" contrast?.....The single package of
>higher-contrast Ultra paper I tried has a cyan cast even on the white borders,
>as well as needing what seemed like an excessive cyan filtration to get half
>decent color balance, so I don't use it. Any comments??
A couple of thoughts, although no definitive answer:
* I believe that most commercial labs use higher contrast materiasl because
people like the "snap" that they give. You'll probably have to use
a higher contrast material to achieve the same effects. Ultra does
come to mind.
* About the cyan cast to the Ultra that you tried: no idea. But when I
gave RA4 a whirl (I'm pretty much strictly an Ilfochrome printer) I
tried Ultra and observed no such effect. I wonder if it might have
been a bad paper batch? Kodak RA4 paper is so cheap that I'd think that
it might be worth trying another 25 sheet envelope of 8x10.
* Although I don't know that it's related, I *am* a little puzzled over
why you're doing replenishment instead of one-shot. The really huge
advantage of doing drum processing is that you can easily do one-shot
processing and you *know* that your chemistry is always good. Really
the only to be sure of it with replenishment is to run process control
strips and that's a big hassle.
I'll note, also, that if your replenishment rate is inadequate, one
of the symptoms will probably be lowered contrast. But, really, I
suspect that the answer is to use a higher contrast paper.
Barry
--
Barry Sherman, Amdahl Corp. | Art does not reproduce what we see.
b...@oes.amdahl.com | It makes us see. -- Paul Klee
My opinions, not Amdahl's |
Kenneth Owen
that
>someone referred to here a while back. I've found that I can usually
control it
>by having neither too much nor too little chemistry in the drum: Checked
it out
>using saran wrap taped over ends of the drum so I could see how things
went.
>Also drum must be level when adding chemistry. If you have a wave-action
roller
>put reference marks on eccentric wheels when drum's in level position:
Always
>bring wheel to that position before adding chemistry.
>
>BUT I never found out which processing step produces the stain; or why,
really.
>Anybody know? -
Alexander
Contrast problems in RA-4 printing can come from a few different areas.
Retained silver from insufficient volume of bleach/fix, inactive or under
oxygenated bleach/fix, or weak developer can all be causes. The weak
developer is generally easiest to notice, since it will normally cause
the black areas of the print to only reach a dark blue tone. If that is
not part of the problem, get some air into your bleach/fix, and/or use a
longer bleach/fix time.
At Jobo we use longer times than generally recommended by the chemical
manufacturers, because of the dynamics of what goes on inside a rotary
processor. We recommend a 30 sec pre-soak in water; 1 min dev; 30 sec
acetic acid stop bath (2% or so); 30 sec water rinse; 1 min bl/fx; 3
consecutive 30 sec water rinses, then dry. This procedure could help 2
of the 3 problems you described. If you have been using 45 sec
developing and bl/fx times, that could cause low contrast. If you have
not been using the acid stop bath AND the water rinse afterward, that can
cause the magenta stains.
Magenta stains are normally caused by a problem with the bl/fx. Most
often it is caused by an excessive carry-forward of developer into the
bl/fx. If you see streaks, they were caused by the developer droplets
running down the print as the bl/fx was added.
Magenta can also be the cause of your low contrast! If you are getting
an overall magenta cast, you may not recognize it as a chemical problem.
Then you will just adjust your magenta filtration to correct for it, but
in doing so, you are creating some neutral density in your prints. The
whites get muddy, and so do the rest of the colors. Try fresh bl/fx. It
may have accumulated some developer content causing the problem for you.
Ken Owen -- JOBO Fototechnic
Tom Saylor
problematic. I never was happy with the quality and could never match a
set. I know it is an amateur system---but nowadays most advanced amateurs
would be well-advised to go to a table-top processor for more
consistency.
Just a few years ago I was in the market for a high end table-top
processor---I looked at the Japanese machines and Durst and Pragmatic
Processor. I finally bought a couple Pragmatic Processors to play
with---mostly because they were the cheapest---both the 11in wide and
20in wide. These dumb little machines taught me alot about the RA4
process and how to modify the process to get the quality of prints I
wanted. Even the junkiest table-top machines can make good consistent
prints (compared to drum processing) if you set-up a manual replenishment
system (I used Kodak Ektacolor ra developer and replenisher mixes) and
keep your rollers scrupulously clean. But if you want really good color
prints I say get rid of the toys and get a real processor which is what I
did.
My first Kreonite was a used 17in wide graphic arts model 3 bath
dry-to-dry model. The thing is at least 10 years old and is still in
almost daily use in our lab. I modified it to run ra-4 and it makes
gorgeous gallery quality color prints. To get the max contrast and
saturation out of the print I deliberately run the machine a little
slower than spec and run my developer at 88 degrees and blix at 95
degrees. My colors are very rich, blacks a deep black with no bluing, and
whites a true white with no cyan cast. Prints comes out the end dry and
ready for sale.
Best of all I can walk away from the machine for a week---let it warm
up---run a couple cleaner sheets through it to clean the rollers---turn
on the wash water and make prints identical to my last session with no
changes to enlarger color settings. I haven't cleaned my tanks in over a
year (the machine has autoreplenishment and filtration for both dev and
blix) and if I need a part for it I can call a dealer and have it Fed-exd
the next day. I've run at least 20,000 16x20 sheets through it in the
past 12 months and loads of small 4x5 test strips. Not once have I had a
paper jam or scratched print.
I paid $2000 for the machine used and have spent $160 on it for parts and
filters in the last year and a half. It runs on 110v. This type of
machine is readily available used at $2500-4000. So-called table-top
processors sell new for the same money (or more) and are toys in
comparison to this thing. You could spend close to $2000 for a Jobo
automatic drum system which is a joke by comparison. Go with a real
machine and your prints can compete with the best custom lab in the
country. And by the way, your chemistry cost will be alot less per print
too. As you know one shot chemistry use can get pretty expensive. I
figure a chemistry cost of about 20 cents per 16x20 print. (we buy in 25
gal kits.)