You are probably right about writing... but I do like the "systemized" feeling and automation of it all... wish I had a cuve plotter to go along with it, to make life simpler; I tend to spend an inhumane amount of time drawing a decent curve!
Originally Posted by Mr Bill
Humm, well there is a problem with the reflection reading head turret...
as is typical with these Macbeths, the polka dotted disk has turned into a UFO
and is now MIA.
Underneath where the disk is supposed to rest, there is a flat region,
(looks like a circle with it's top 20% cut off) that must be up or down
(lets say down)
when ever the densitometer is set to one of its options (C, M, Y or Vis).
If someone's is loose and they don't mind looking,
it would be nice to know which way the flat piece is supposed to face when the machine is set to read "visual".
Right now I am optomistic.
The only two real issues are the missing disk on the turret and
a dislodged diffuser on the "null density" switch light.
Should be a piece of cake to identify the "who is what". Temporaily mark the turret with some sort of ID. Then, find a few color samples to read: red, green, and blue. Not too critical, photos with a bright red ball cap, green leaves, etc. Reading the red object, whichever turret position gives the LOWEST DENSITY is the red-filter position, likewise green test target for green-filter position, and same for blue. The remaining turret position is the visual filter. If there's any question about the blue filter (a lot of people would identify a cyan test color as blue), try reading a yellow test patch - this time the HIGHEST density reading identifies the turret's blue-filter position.
Originally Posted by Ray Rogers
Yes, I have a "sense" that it should not be too dificult...
Originally Posted by Mr Bill
There are a few complications that make it less clear to me however...
perhaps you can follow the logic "deeper" than I can and point to the light
at the end of the tunnel? At least I hope so.
I don't have the model specfic data,
so I am not sure the locations on the turret are in fact R,G,B & Vis or Ortho....
some 900 series machines are c,y,m & V/O
(although most do seem to be RGB & V/O)
If the machine I have is not RGB how will that affect our "Who's Who" test if I use Red , green and Blue-ish quick and dirty test objests and don't bother to use known real samples...
More over, what is it good for?
(For what it's worth I do have a macbeth color card - if that might help)
To read ANY channel, The machine has to be zeroed.
Since I don't yet know which channel is visual, will zeroing on one of the other channels (of either R,G,B or C,M,Y) somehow invalidate the results of our
"Who's Who" test?
Complication 2 - Just zero and calibrate ALL (4) channels. At the end of this post are results I get on a Macbeth ColorChecker (the full-size one, not the tiny one). You should be able to "zero" all of you colors, individually, on the "White" patch - check your calibration on the Black patch, at about 1.52.
BTW, the color signals should be so strong, that even a large calibration error won't matter, with respect to finding "who's who."
Complication 1- All densitometers I know of work pretty much the same - they insert some sort of narrow band filter, either red, or green, or blue, into the light path, so that the result effectively tells how much of a dye, cyan, or magenta, or yellow, is present. That is, a densitometer who's turret is labeled CMY could just as well have been labeled RGB. In general photography, we would use a set of responses they call "Status A" for things we visually observe, such as prints or slides. "Status M" would be for color negs, which are intended to be printed, not directly viewed. I know that there are some graphic arts versions, such as Status T and E (?), which used slightly different versions of the red, green, and blue filters.
Here's the data I get reading one example of an actual Macbeth card - I used an X-rite 810 (Status A)
Results are listed, for each Macbeth patch, in order of: R,G, B, then Vis.
White = 0.05, 0.05, 0.06, 0.05
Black = 1.53, 1.52, 1.51, 1.52
Red = 0.23, 1.36, 1.34, 0.79
Green = 1.08, 0.50, 1.23, 0.70
Blue = 1.43, 1.31, 0.54, 1.36
note: this is just one sample, there is probably some fair amount of variation in cards. Nevertheless, there is never any doubt about which turret setting has the lowest density, for Macbeth red, green, and blue.
Definitely send X-Rite an e-mail and ask them. They were very helpful to me.
"I only wanted Uncle Vern standing by his new car (a Hudson) on a clear day. I got him and the car. I also got a bit of Aunt Mary's laundry, and Beau Jack, the dog, peeing on a fence, and a row of potted tuberous begonias on the porch and 78 trees and a million pebbles in the driveway and more. It's a generous medium, photography." -- Lee Friedlander
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Thanks for going to the trouble.
I pulled out my MCC today;Was going toi do today, butgot sidetracked when I found software fore putting the measurments into excell, but discovered my cable seems not to be the RS232 Dsub25 nor the Dsub 9, but an HRS (Hirose) RC40-24PR for which I have no idea what to do with....
I should to the MCC testing tomorrow, or at the latest, sometime thereafter.
Thanks for the advice... is that the same as Sam C... or, to be more clear,
How did you contact them?
(Do you still have their email address?)
You're quite welcome!
Hope you can find the cabling parts. If it IS an RS232 line, I would expect it to have the 25pin connector.
Might be IEEE-448. http://en.wikipedia.org/wiki/IEEE-488
Originally Posted by Ray Rogers
Gee my last post had quite a few typos!
Well- I sought confirmation from several angles and it seems things are straightened out.
I used Mr. Bill's data to cross check results obtained from trying to follow one (official) repairman's help.
There are/were 2 issues:
My lowest values were obtained when the complementary color
to that indicated by Mr Bill, was set.
According to the comments about RGB and CMY being sort of interchangable,
perhaps this is a non-issue.
The other issue is that I seem to get a stronger M & Y response
(G & B according to the above mentioned logic) in the MCC White patch.
My Light is quite yellowish... is this normal?
Are they generally useable till they die?
Or, are they supposed to be used for some % of their entire life?
Anyway, here is the data I got with my set up and color checker.
(I will follow Mr. Bills layout)
Here's the data I get reading one example of a Macbeth card
Results are listed, for each Macbeth patch, in order of:
R,G, B, then Vis.
(actually in my case: C, M, Y then Vis.)
White = 0.06, 0.09, 0.15, 0.06
Black = 1.53, 1.53, 1.51, 1.52
Red = 0.25, 1.38, 1.31, 0.82
Green = 1.11, 0.50, 1.20, 0.66
Blue = 1.37, 1.28, 0.60, 1.24
Different machines, different cards yet fairly close.
The one white patch does look a bit (0.15) yellowish;
The card is old, yet nearly unused and was stored in the dark, in original pkg.
Last edited by Ray Rogers; 04-20-2011 at 09:41 PM. Click to view previous post history.
RC40-24PR is probably the venerable GPIB, common in older lab equipment.