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Reflective Densitometer Method

Reflective Densitometer Method

2002-10-19 by Martin Wesley

I am fooling around with a used X-Rite 811 transmission/refection densitometry I picked up on eBay and I have a couple of questions for any experts on sensitometry lurking out there.

 

In reading reflective density of inkjet prints there is the issue that the paper is not completely opaque. You can see light though even the heaviest papers we are using. So when measuring image density the print being measured needs to be backed up with an opaque material. My question is should this be white, as in stacking up several pieces of paper under the print or should it be black? My inclination is to use black so that no light that passes through the paper gets bounced back, since this would logically seem to falsely increase the reflectance and lower the density reading. The calibration plaques are enameled metal so I assume the instrument expects to see a 100% opaque reflective target.

 

Dumb question: How do you convert RGB densities to CMY densities or do they simply equal their color opposites?

 

The 811 has two transmission modes, one for E-6 and one for C-41. Which would be the best for standard developed B&W film? Which mode would be best for yellow/green stained pyro developed B&W film?


Martin Wesley

http://www.borderless-photos.de/guests.html




[Non-text portions of this message have been removed]

RE: [Digital BW] Reflective Densitometer Method

2002-10-19 by Lloyd O'Daniel

Martin,
 
I've had a X-rite 810 for several years now. Your 811 is even a better
instrument. RGB does equal CMY. R= -C, G= -M, B= -Y. For B&W negs, the
811 should have a visual density (grey) mode. On the 810, this is
labeled T-VIS in the display.  You would use Status M color densities
for process control of C41 neg films, and Status A densities for E6. The
reflective mode should be Status A for reading prints. If your unit did
not come with a manual, you can buy one from X-rite. You also need
transmission and reflective calibration wedges from them as well.
 
Lloyd
Show quoted textHide quoted text
-----Original Message-----
From: Martin Wesley [mailto:mwesley250@...] 
Sent: Saturday, October 19, 2002 2:00 AM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: [Digital BW] Reflective Densitometer Method


I am fooling around with a used X-Rite 811 transmission/refection
densitometry I picked up on eBay and I have a couple of questions for
any experts on sensitometry lurking out there.



In reading reflective density of inkjet prints there is the issue that
the paper is not completely opaque. You can see light though even the
heaviest papers we are using. So when measuring image density the print
being measured needs to be backed up with an opaque material. My
question is should this be white, as in stacking up several pieces of
paper under the print or should it be black? My inclination is to use
black so that no light that passes through the paper gets bounced back,
since this would logically seem to falsely increase the reflectance and
lower the density reading. The calibration plaques are enameled metal so
I assume the instrument expects to see a 100% opaque reflective target.



Dumb question: How do you convert RGB densities to CMY densities or do
they simply equal their color opposites?



The 811 has two transmission modes, one for E-6 and one for C-41. Which
would be the best for standard developed B&W film? Which mode would be
best for yellow/green stained pyro developed B&W film?


Martin Wesley

http://www.borderless-photos.de/guests.html




[Non-text portions of this message have been removed]



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[Non-text portions of this message have been removed]

Re: Reflective Densitometer Method

2002-10-19 by Jeff Randall

--- In DigitalBlackandWhiteThePrint@y..., "Martin Wesley" 
<mwesley250@e...> wrote:
SNIP
> In reading reflective density of inkjet prints there is the issue 
that the paper is not completely opaque. You can see light though 
even the heaviest papers we are using. So when measuring image 
density the print being measured needs to be backed up with an opaque 
material. My question is should this be white, as in stacking up 
several pieces of paper under the print or should it be black?
SNIP

Martin:  

Paul Roark and I discovered this discrepancy recently when reporting 
on the offwhite EAM when I asked him exactly how he made his 
measurements with his swatchbook because I was not getting the same 
results.  I had discovered, as I played with my new 
swatchbook, that backing color and opacity DOES make a difference.   
As you have now discovered, the standard of practice is, and typical
instructions say to use an opaque black backing to absorb any back 
reflected light.  However, the reasoning that I use to justify an 
opaque white backing (like Paul) is that I frame my prints and use an 
opaque white backing. So I want to measure what I will see.  
Consistancy (using the same backing color and opacity) is also very 
important. 

Jeff Randall

RE: [Digital BW] Reflective Densitometer Method

2002-10-19 by Paul Roark

Martin,

I use a stack of white paper under the target just on the assumption that a
print will be mounted on an off-white mat board.  Consistency is probably
the most important thing.

Paul
___________________________
Show quoted textHide quoted text
  -----Original Message-----
  From: Martin Wesley [mailto:mwesley250@...]
  Sent: Friday, October 18, 2002 11:00 PM
  To: DigitalBlackandWhiteThePrint@yahoogroups.com
  Subject: [Digital BW] Reflective Densitometer Method


  I am fooling around with a used X-Rite 811 transmission/refection
densitometry I picked up on eBay and I have a couple of questions for any
experts on sensitometry lurking out there.



  In reading reflective density of inkjet prints there is the issue that the
paper is not completely opaque. You can see light though even the heaviest
papers we are using. So when measuring image density the print being
measured needs to be backed up with an opaque material. My question is
should this be white, as in stacking up several pieces of paper under the
print or should it be black? My inclination is to use black so that no light
that passes through the paper gets bounced back, since this would logically
seem to falsely increase the reflectance and lower the density reading. The
calibration plaques are enameled metal so I assume the instrument expects to
see a 100% opaque reflective target.



  Dumb question: How do you convert RGB densities to CMY densities or do
they simply equal their color opposites?



  The 811 has two transmission modes, one for E-6 and one for C-41. Which
would be the best for standard developed B&W film? Which mode would be best
for yellow/green stained pyro developed B&W film?


  Martin Wesley

  http://www.borderless-photos.de/guests.html




  [Non-text portions of this message have been removed]


        Yahoo! Groups Sponsor
              ADVERTISEMENT




  Please visit the Group Homepage to check the Files, Bookmarks, Polls and
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page.

  Please follow these basic guidelines:
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them short.
  - As the topic of a thread changes remember to change the subject header.
  - Good manners are required at all time. No personal attacks or
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[Non-text portions of this message have been removed]

Re: Reflective Densitometer Method

2002-10-19 by Antonis Ricos

Martin,

some "reflections" on your post:


> In reading reflective density of inkjet prints there is the issue that the paper is 
not completely opaque.

With my 810 I find that on EAM I get the same readings whether I back it with 
black or leave it alone. However, backing it with a second sheet raises the 
paper white from 0.06 to 0.04. By the time you get to 15-20% of a grayscale 
the difference is about 0.01 which is lost in the "noise" of the instrument. For 
practical purposes, I always read EAM and Hahnemuhle without backing. 

Consistency matters, but I can also see the argument that backing it with white 
matches a matted print better. In any case, worth disclosing when we compare 
notes on highlight densities.

Insterestingly, the DTP41 (XRite's strip reading spectrophotometer) has a 
block under the sensor that can be moved to either white or black. The 
instructions for PrintOpen, Heidelberg's profile-making software, asks that you 
slide it over to expose the _white_  patch under the sensor.




> The 811 has two transmission modes, one for E-6 and one for C-41. Which 
would be the best for standard developed B&W film? 


Visual, marked as T VIS for transmissive ( R VIS for paper).


Which mode would be best for yellow/green stained pyro developed B&W 
film?

Essentially none, but probably whichever gives you better separation of 
values. These densitometers separate the spectrum into the 3 primaries 
based on the peak frequency of the photographic color process dyes for 
which their "status" is intended. Outside of that, their color readings are 
meaningless as far as any standard reference goes and only useful as 
"relative" values (perfectly functional for your purposes).

Antonis

Re: Reflective Densitometer Method

2002-10-19 by sceptre12345

It seems the only difference between the two is X-rite 811 has status 
A response for monitoring of E-6
Andre

--- In DigitalBlackandWhiteThePrint@y..., "Austin Franklin" 
<darkroom@i...> wrote:
> 
> Lloyd,
> 
> > I've had a X-rite 810 for several years now. Your 811 is even a 
better
Show quoted textHide quoted text
> > instrument.
> 
> I'm curious what you think is better about the 811?
> 
> Austin

RE: [Digital BW] Reflective Densitometer Method

2002-10-19 by Lloyd O'Daniel

The Status A transmission capability. I "rigged" my 810 to do that by
buying a status A sensor module, since one of my primary uses for the
810 was process monitoring of E6 for my Jobo ATL-2. The 811 would be
more accurate at high densities though, because the 810's internal
electronics are calibrated for status M.
 
Lloyd
Show quoted textHide quoted text
-----Original Message-----
From: Austin Franklin [mailto:darkroom@...] 
Sent: Saturday, October 19, 2002 8:51 AM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: RE: [Digital BW] Reflective Densitometer Method



Lloyd,

> I've had a X-rite 810 for several years now. Your 811 is even a better
> instrument.

I'm curious what you think is better about the 811?

Austin



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[Non-text portions of this message have been removed]

Re: [Digital BW] Reflective Densitometer Method

2002-10-20 by Martin Wesley

----- Original Message -----
Show quoted textHide quoted text
From: "Lloyd O'Daniel" <lodaniel@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Saturday, October 19, 2002 4:11 PM
Subject: RE: [Digital BW] Reflective Densitometer Method


> The Status A transmission capability. I "rigged" my 810 to do that by
> buying a status A sensor module, since one of my primary uses for the
> 810 was process monitoring of E6 for my Jobo ATL-2. The 811 would be
> more accurate at high densities though, because the 810's internal
> electronics are calibrated for status M.
>

Lloyd,

You may not be far off on the accuracy since the same calibration target and
values are use for both the Ta and Tm modes on the 811. Good bit of info on
converting the 810 though. I would think the E6 capability would be of more
use to photographers as I don't know anyone doing their own C-41 processing.

Martin Wesley

http://www.borderless-photos.de/guests.html

RE: [Digital BW] Reflective Densitometer Method

2002-10-20 by Lloyd O'Daniel

Martin,
 
That's what I was told by X-rite, although they were trying to sell an
expensive upgrade to an 811 at the time. ;-)
 
My unit originally came out of a C-41 minilab who traded up to a more
automated model.
 
Lloyd
Show quoted textHide quoted text
-----Original Message-----
From: Martin Wesley [mailto:mwesley250@...] 
Sent: Sunday, October 20, 2002 2:14 AM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: Re: [Digital BW] Reflective Densitometer Method




Lloyd,

You may not be far off on the accuracy since the same calibration target
and
values are use for both the Ta and Tm modes on the 811. Good bit of info
on
converting the 810 though. I would think the E6 capability would be of
more
use to photographers as I don't know anyone doing their own C-41
processing.

Martin Wesley





[Non-text portions of this message have been removed]

Re: [Digital BW] Reflective Densitometer Method

2002-10-23 by Bob Frost

Martin,

I seem to remember that Bruce Fraser and David Tobie both recommend stacking
multiple copies of the same paper under the target.

bob Frost.
Show quoted textHide quoted text
----- Original Message -----
From: "Martin Wesley" <mwesley250@...>


> In reading reflective density of inkjet prints there is the issue that the
paper is not completely opaque. You can see light though even the heaviest
papers we are using. So when measuring image density the print being
measured needs to be backed up with an opaque material. My question is
should this be white, as in stacking up several pieces of paper under the
print or should it be black? My inclination is to use black so that no light
that passes through the paper gets bounced back, since this would logically
seem to falsely increase the reflectance and lower the density reading. The
calibration plaques are enameled metal so I assume the instrument expects to
see a 100% opaque reflective target.

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