----- Original Message -----
From: "Peifer, William [OCDUS]" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: April 6, 2001 9:41 AM
Subject: RE: > Subject: Re: bad processing
> Tom V. wrote:
> >> What if we shoot a color chart, and adjust the mix so
> >> that looks correct, and then contact print?
>
> And William Robb replied:
> > That would be the most accurate method.
> > William Robb
>
> Hi Bill,
>So I've
> got two questions you or one of the other list members might
have answers
> to. First, are there any 18-color cards -- like the
Macbeth -- available at
> a price cheaper than $60?
Here is a strategy that I have used in the past. Go to your
local Wal-Mart and, in the paint department, you will find a
large rack of paint samples, in all the colours of the rainbow.
Get as many as you want. Glue them to a piece of card stock. I
would get what visually appeared to be as close to what I
considered to be the primary and secondary colours (CMY/RGB.
Also a black, white, and middle gray (take a gray card along for
this.) You might also want to include a "flesh" toned patch. It
is also desirable to have middle densities of the 6 colours.
While it is not the industry standard, it is, at least, a pretty
stable reference. In 30 years of photography and >20 years of
photofinishing I have not ever seen a Macbeth chart for real.
Second, suppose I take a shot of such a color
> card with every roll I shoot. Will the typical Fuji or Kodak
consumer lab
> machine process my entire roll using a single set of color
settings,
> optimized from this first negative, or will it readjust color
settings for
> each frame printed?
No, it will only print the the negative of the colour card at
the setting it uses for that scene type. Every other negative on
the roll is a different scene type, so will get it's own colour
balance.
Having said that, I also know that the filtration levels for any
particular film are absolute values for that film. What throws
this off are exposure variables, where we have to correct for
paper slope, and for film slope. Scene type also affects things,
as the machine will try to adjust the colour to what it
considers a neutral. If a scene has an exess of blue, for
example, the machine may tend to print that negative too yellow,
which is the opposite of blue. We call this colour failure.
>In other words, will having a color card on my first
> negative "help" the machine to optimize a single set of color
settings, to
> be used throughout the entire roll, or does proper setting
depend on a
> skilled machine operator (which I very likely won't find in a
consumer lab
> anyway) manually setting the machine?
If you can get an operator who is willing (good luck), you could
have him or her set up a film channel using your reference as a
standard. Stick with the same film type, and you will get
consistent results, as long as the lab holds up their end of the
stick.
Since you are making a reference standard, you will want to
include, in your control negative set, a negative that is 2
stops under exposed, one that is correctly exposed, one that is
3 stops over exposed, and one that is 5 stops over exposed.
Use the same shutter speed for each negative, and vary only the
aperture if possible. This will negate the possibility of minor
colour reciprocity failure. You will likely find that the +5
exposure will require a slower shutter speed, but you also
shouldn't be producing many negs in this density range.
What this does is to create a tool that the lab can use to set
up their machine to your camera/lens/film combination over a
fairly broad exposure range.
Tools of this sort are available commercially. Aperion makes a
kit called True-Balance®, which is a set of negatives as
described above. When I bought one about 10 years ago, I paid
just over CAN$300.00. I would not waste the money again on a
True-Balance® kit. I would just make my own.
A reference standard is, after all, only an arbitrary constant.
If anyone is interested in the Zone system of black and white, I
can tell you how to make a reference standard for the Zone
system for the price of a few sheets of B&W photo paper.
William Robb
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