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ExpoDisc Conversation with Diane Wallace

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pbleic

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After receiving my shipping acknowledgement on the ExpoDisc, I gave Diane Wallace a call. She is the current owner of the company. As you probably know from the site, she is the daughter of George Wallace, a student of Ansel Adams and expert in the Zone System. He originally designed the disk to get perfect Zone 5 exposures.

Not surprisingly, they have seen a little "spike" in sales over the past week. We had a long and very interesting conversation, followed by some emails from her. Some are quite interesting and I will share them.

First, here is an email on testing the ExpoDisc by Kevin Kubota, a very well known digital photography educator/digital photographer: http://www.kubotaworkshops.com/pages/info.html

-----Original Message-----
From: Kevin Kubota [ [email protected]]
Sent: Sunday, March 14, 2004 9:46 PM
To: Diane Wallace; 'Laurie Love'; Chris Stocker; 'Erik and Erica Sowder'
Cc: [email protected]; 'Mary T. Mannix'; Craig Strong
Subject: ExpoDisc vs. Pringles vs. AutoWB vs. Dirty Gym Socks

It's funny to see all the comparisons to the ExpoDisc. I've done a few of my
own.

I used a Nikon D100 and a table lamp to test different WB methods. I
compared the ExpoDisc, the infamous Pringles lid, Auto White Balance, and
Dirty Gym socks.

I tested by taking the first WB setting with ExpoDisc, brought it into
Photoshop CS and ran the AVERAGE filter to normalize any vignetting and
stray pixels. The result is a even color field representing the average
color cast - essentially a grey card. As expected the ExpoDisc provided
PERFECTLY matching RGB values - indicating perfect WB.

Knowing that the ExpoDisc provides perfect WB, I then set the WB using the
other methods, then shot a grey frame with the ExpoDisc over the lens. I
brought all the frames into PS CS, ran the AVERAGE filter and noted the
results with the eyedropper.

Here are the results and the .jpg files are attached.

ExpoDisc R:94 G:94 B:94
Pringles R:88 G:95 B:101 (too much blue cast)
AutoWB R:123 G:98 B:34 (very warm. Yikes! people actually trust Auto?!)
Dirty Sock R:125 G:99 B:72 (Way off and smelly too)

Similarly off results are gained with coffee filters, panty hose, garden
hoses, tracing paper, diffusion fabric, table cloths, dress socks, frosted
glass, plastic grocery bags, and organic rice paper imported from old world
Japan.

Besides, none of the above come with the cool little neck strap dangly.

Aloha,
Kevin Kubota
Member said:
----------------------------------> >
Click to expand...
Kubota Photo-Design, Inc.
Drake Award Winning website
See it: http://www.kkphoto-design.com
email: [email protected]
Cheap: (541) 330-6633
Free: (800) 738-2249
Fax: (541) 330-5540
 
Also from Diane:

THE FOLLOWING RESPONSE IS FROM CLAUDE JODOIN, Technical Editor for Rangefinder Magazine:

Phil Davis, Professor Emeritus @ University of Michigan, and author of Beyond the Zone System (probably the source of this confusion as well) once told me that an 18% gray card was the middle of a 5-Stop dynamic range. We a generally recording and printing for a 3-11 stop dynamic range in Black and White (using Zone System compander techniques). This means that different value placements my be required, depending on the dynamic range of the scene. A "perfect" exposure can be illusive in nature because the dynamic range varies with weather and subjects. That "perfect exposure" may not always be the one we want to see. This, on top of meter manufacturing tolerance of plus or minus 1/3 stop (allowed by the ISO) and the tolerance of the chips themselves, the exposure can vary by 2/3 stop when everything is working right.

This is why I have taught Personal Metering Calibration workshops in both film and digital. Whithout this crucial step, you never know where your meter stands. Also, there are variations in technique and interpretation that creep in along with someone's subjective definiton of desired tonal values.

Most printing papers have a DENSITY range of about 6-7 stops, from 0.05 (Dmin, pure white, no detail) to 2.15 (Dmax, pure black, no detail) along with various abilities (disabilities?) in between to render visual separation of recorded information.

18% diffuse reflective readings of a gray card at an exact compound angle 1/2 way between the source and camera lens axis, with no source specualrity to affect the metered value require some degree of precision, which is tough to repeat. Why? Because gray cards, being flat objects in a round world, do not have built-in "cosine compensation" to correctly average in the light angles striking a 3D subject. The Expos Disc does and so do hemispherical domes on incident light meters.

The answer? Make the meters work for you by properly looking at the RBG values of your files. In digital photography, the most important value is diffuse white (the back side of gray card, or 90% reflective), which should render at about 235, 235, 235, RGB value in Photoshop. Whatever means necessary to accomplish this should be used. I find that once the photographer has compensated for internal meter and external meter errors, the ExpoDisc accomplishes the task of lining up those 3 numbers more accurately and efficiently than any other means I have tried. It's a passive device that is far more precise in manufacture and utterly dependable once all the other electronic manufacturing and performance variables have been tweaked out of the system.
 
There is apparently a very technical analysis of the ExpoDisc upcoming in the next issue of the British Journal of Photography. It includes a stunning graph showing accuracy of the device over a wide range of EVs. You should look for this when it comes out - the graph tells the whole story.
-
Paul

------------------------------------------------
Pbase supporter
Photographs at: http://www.pbase.com/pbleic
--------------------------------------------------
Copyright 2003, 2004 All rights reserved.
 
Paul,

Thanks so much for keeping us up-to-date with your findings in thie area.

I was very intrested in your mention of your conversation with Diane Wallace.

I enjoyed your "first" item, the e-mail from Kevin Kubota to Diane Wallace.

I'd enjoy seeing the "next" item. Perhsps it would be something from Diane.

Thanks again.

Best regards,

Doug
pbleic said:
Not surprisingly, they have seen a little "spike" in sales over the
past week. We had a long and very interesting conversation,
followed by some emails from her. Some are quite interesting and I
will share them.

First, here is an email on testing the ExpoDisc by Kevin Kubota, a
very well known digital photography educator/digital photographer:
http://www.kubotaworkshops.com/pages/info.html

-----Original Message-----
From: Kevin Kubota [ [email protected]]
Sent: Sunday, March 14, 2004 9:46 PM
To: Diane Wallace; 'Laurie Love'; Chris Stocker; 'Erik and Erica
Sowder'
Cc: [email protected]; 'Mary T. Mannix'; Craig Strong
Subject: ExpoDisc vs. Pringles vs. AutoWB vs. Dirty Gym Socks

It's funny to see all the comparisons to the ExpoDisc. I've done a
few of my
own.

I used a Nikon D100 and a table lamp to test different WB methods. I
compared the ExpoDisc, the infamous Pringles lid, Auto White
Balance, and
Dirty Gym socks.

I tested by taking the first WB setting with ExpoDisc, brought it into
Photoshop CS and ran the AVERAGE filter to normalize any vignetting
and
stray pixels. The result is a even color field representing the
average
color cast - essentially a grey card. As expected the ExpoDisc
provided
PERFECTLY matching RGB values - indicating perfect WB.

Knowing that the ExpoDisc provides perfect WB, I then set the WB
using the
other methods, then shot a grey frame with the ExpoDisc over the
lens. I
brought all the frames into PS CS, ran the AVERAGE filter and noted
the
results with the eyedropper.

Here are the results and the .jpg files are attached.

ExpoDisc R:94 G:94 B:94
Pringles R:88 G:95 B:101 (too much blue cast)
AutoWB R:123 G:98 B:34 (very warm. Yikes! people actually trust
Auto?!)
Dirty Sock R:125 G:99 B:72 (Way off and smelly too)

Similarly off results are gained with coffee filters, panty hose,
garden
hoses, tracing paper, diffusion fabric, table cloths, dress socks,
frosted
glass, plastic grocery bags, and organic rice paper imported from
old world
Japan.

Besides, none of the above come with the cool little neck strap
dangly.

Aloha,
Kevin Kubota
pbleic said:
----------------------------------> >
Click to expand...
Kubota Photo-Design, Inc.
Drake Award Winning website
See it: http://www.kkphoto-design.com
email: [email protected]
Cheap: (541) 330-6633
Free: (800) 738-2249
Fax: (541) 330-5540

--
Click to expand...
 
After all of the technical testing and reporting, I shot a CW shot of a Pringles lid yesteday. When put in PS8, the color values were R-107, G-107, B-107. The follwoing pics were great.

So great going all you technical experts, but for me the Pringles lid works very well.
Doug Kerr said:
Thanks so much for keeping us up-to-date with your findings in thie
area.

I was very intrested in your mention of your conversation with
Diane Wallace.

I enjoyed your "first" item, the e-mail from Kevin Kubota to Diane
Wallace.

I'd enjoy seeing the "next" item. Perhsps it would be something
from Diane.

Thanks again.

Best regards,

Doug
pbleic said:
Not surprisingly, they have seen a little "spike" in sales over the
past week. We had a long and very interesting conversation,
followed by some emails from her. Some are quite interesting and I
will share them.

First, here is an email on testing the ExpoDisc by Kevin Kubota, a
very well known digital photography educator/digital photographer:
http://www.kubotaworkshops.com/pages/info.html

-----Original Message-----
From: Kevin Kubota [ [email protected]]
Sent: Sunday, March 14, 2004 9:46 PM
To: Diane Wallace; 'Laurie Love'; Chris Stocker; 'Erik and Erica
Sowder'
Cc: [email protected]; 'Mary T. Mannix'; Craig Strong
Subject: ExpoDisc vs. Pringles vs. AutoWB vs. Dirty Gym Socks

It's funny to see all the comparisons to the ExpoDisc. I've done a
few of my
own.

I used a Nikon D100 and a table lamp to test different WB methods. I
compared the ExpoDisc, the infamous Pringles lid, Auto White
Balance, and
Dirty Gym socks.

I tested by taking the first WB setting with ExpoDisc, brought it into
Photoshop CS and ran the AVERAGE filter to normalize any vignetting
and
stray pixels. The result is a even color field representing the
average
color cast - essentially a grey card. As expected the ExpoDisc
provided
PERFECTLY matching RGB values - indicating perfect WB.

Knowing that the ExpoDisc provides perfect WB, I then set the WB
using the
other methods, then shot a grey frame with the ExpoDisc over the
lens. I
brought all the frames into PS CS, ran the AVERAGE filter and noted
the
results with the eyedropper.

Here are the results and the .jpg files are attached.

ExpoDisc R:94 G:94 B:94
Pringles R:88 G:95 B:101 (too much blue cast)
AutoWB R:123 G:98 B:34 (very warm. Yikes! people actually trust
Auto?!)
Dirty Sock R:125 G:99 B:72 (Way off and smelly too)

Similarly off results are gained with coffee filters, panty hose,
garden
hoses, tracing paper, diffusion fabric, table cloths, dress socks,
frosted
glass, plastic grocery bags, and organic rice paper imported from
old world
Japan.

Besides, none of the above come with the cool little neck strap
dangly.

Aloha,
Kevin Kubota
Doug Kerr said:
----------------------------------> >
Click to expand...
Kubota Photo-Design, Inc.
Drake Award Winning website
See it: http://www.kkphoto-design.com
email: [email protected]
Cheap: (541) 330-6633
Free: (800) 738-2249
Fax: (541) 330-5540

--
Click to expand...
Click to expand...
--

 
Paul,

Very interesting.

What he is talking about (beyond the numerical value of the "test target" reflectance) seems to be the fact that a gray card will not necessarily exhibit "Lambert's law" behavior. I thought it might be useful, to discuss Lambert's law a bit, as it figures prominently into many aspects of exposure and exposure measurement.

There are two prongs to Lambert's law. For an illuminated diffuse (non-specular; that is, not in any way "mirror-like") surface obeying Lambert's law:

1. The luminance of the surface appears the same from any direction of observation on its front side (that is, from any direction over the the hemisphere).

2. That luminance is proportional to the illuminance upon the surface, regardless of the angle of incidence (the angle at which the light arrives).

3. [Not part of Lambert's law, but needed to explain 2 above, and to explain the point here] The illuminance on a surface is the product of the arriving luminous flux density (a measure of the "potency" of the arriving light) and the cosine of the angle between the axis of arrival and a line perpendicular to the surface.

Point 3 comes about from the fact that "luminous flux density" is reckoned in terms of luminous flux (the "stuff" of light) per unit area, where area is reckoned in a plane perpendicular to the direction of travel of the light. Suppose that, just before the light strikes our surface, its luminous flux density is 100 lumens per square centimeter.

Suppose we use a mask with a square hole in it 1 cm on a side (an area of one square cm) and we hold it near the surface of interest and perpendicular to the arrival direction of he light. Then 100 lumens of luminous flux will pass through it and strike the surface.

But suppose the direction of arrival of the light is at 45° to a line perpendicular to the surface. Then our "square shaft" of light will illuminate a patch 1 cm x 1.414 cm in size. (This is just the reason that shadows cast by light not arriving from overhead are larger than the object casting the shadow.) It's area is 1.414 square cm.

Thus the illuminance on that part of the surface is 0.707 lumens per square cm (1/1.414).

Among other things, this is why, in measuring incident light for exposure purposes, we must have the axis of the meter receiver pointed in a direction perpendicular to the surface of interest, not:

a. Toward the light source, or
b. Toward the camera

(Of course, that could turn out to be one of those directions.)

Now, for that to work, the response of the meter, like the behavior of a "Lambertian" surface, should be proportional, for each components of the arriving light, to the luminance that component would cause on a surface perpendicular to the "axis" of the meter. Presumably, the ExpoDisc seeks to bring about this situation when it is mounted on a camera lens.

Note that this is not the same thing as "uniform response to light from every direction of arrival". We don't want that, because that is not how our typical subject surface responds (see again items 2 and 3 above). This is a widespread misunderstanding about the behavior of incident light meters. We do want it to respond (following the "cosine law" to light from every direction over a hemisphere.

We can make a measurement of incident luminance by allowing the incident light to fall on a neutral test target of known reflectance placed parallel to the surface of interest (a wrinkle to the "gray card" technique that is often overlooked) and then,measuring its luminance from any handy direction! But this will only be accurate if the test target truly obey's Lambert's law.

This is in fact the point from which I started this discussion.

Best regards,

Doug
 
Mjack1957 said:
http://forums.dpreview.com/forums/read.asp?forum=1031&message=8071656
RATPhoto said:
I'm glad it is working for you but showing the tests shots would be
good (in the seperate thread you started).

--
If you are a new user chances are good your question is answered in
the FAQ at:
http://www.marius.org/eos300dfaq.php

For a gallery of my photographs, see:
http://www.pbase.com/ratphoto

See my profile for my equipment
Click to expand...
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Click to expand...
--
If you are a new user chances are good your question is answered in the FAQ at:
http://www.marius.org/eos300dfaq.php

For a gallery of my photographs, see:
http://www.pbase.com/ratphoto

See my profile for my equipment
 
After going back and reacquainting myself with the website, something you said just struck me. Why would the sizes be jacked up to such a premium (my largest lens is 82mm now) if the reading is done from the center only? I always figured filters are priced accordingly because they are expected to work consistently all the way to the edges. ~ m²
pbleic said:
Not surprisingly, they have seen a little "spike" in sales over the
past week. We had a long and very interesting conversation,
followed by some emails from her. Some are quite interesting and I
will share them.

First, here is an email on testing the ExpoDisc by Kevin Kubota, a
very well known digital photography educator/digital photographer:
http://www.kubotaworkshops.com/pages/info.html

-----Original Message-----
From: Kevin Kubota [ [email protected]]
Sent: Sunday, March 14, 2004 9:46 PM
To: Diane Wallace; 'Laurie Love'; Chris Stocker; 'Erik and Erica
Sowder'
Cc: [email protected]; 'Mary T. Mannix'; Craig Strong
Subject: ExpoDisc vs. Pringles vs. AutoWB vs. Dirty Gym Socks

It's funny to see all the comparisons to the ExpoDisc. I've done a
few of my
own.

I used a Nikon D100 and a table lamp to test different WB methods. I
compared the ExpoDisc, the infamous Pringles lid, Auto White
Balance, and
Dirty Gym socks.

I tested by taking the first WB setting with ExpoDisc, brought it into
Photoshop CS and ran the AVERAGE filter to normalize any vignetting
and
stray pixels. The result is a even color field representing the
average
color cast - essentially a grey card. As expected the ExpoDisc
provided
PERFECTLY matching RGB values - indicating perfect WB.

Knowing that the ExpoDisc provides perfect WB, I then set the WB
using the
other methods, then shot a grey frame with the ExpoDisc over the
lens. I
brought all the frames into PS CS, ran the AVERAGE filter and noted
the
results with the eyedropper.

Here are the results and the .jpg files are attached.

ExpoDisc R:94 G:94 B:94
Pringles R:88 G:95 B:101 (too much blue cast)
AutoWB R:123 G:98 B:34 (very warm. Yikes! people actually trust
Auto?!)
Dirty Sock R:125 G:99 B:72 (Way off and smelly too)

Similarly off results are gained with coffee filters, panty hose,
garden
hoses, tracing paper, diffusion fabric, table cloths, dress socks,
frosted
glass, plastic grocery bags, and organic rice paper imported from
old world
Japan.

Besides, none of the above come with the cool little neck strap
dangly.

Aloha,
Kevin Kubota
pbleic said:
----------------------------------> >
Click to expand...
Kubota Photo-Design, Inc.
Drake Award Winning website
See it: http://www.kkphoto-design.com
email: [email protected]
Cheap: (541) 330-6633
Free: (800) 738-2249
Fax: (541) 330-5540

--
Click to expand...
--
Enjoy life - spend your clothing budget on lenses
http://rhodeymark.instantlogic.com/PhotoGallery.ilx

 
The remarks were not meant to impress anyone but to imform them. You'll have to look else where for inspiration.
RATPhoto said:
Mjack1957 said:
http://forums.dpreview.com/forums/read.asp?forum=1031&message=8071656
RATPhoto said:
I'm glad it is working for you but showing the tests shots would be
good (in the seperate thread you started).

--
If you are a new user chances are good your question is answered in
the FAQ at:
http://www.marius.org/eos300dfaq.php

For a gallery of my photographs, see:
http://www.pbase.com/ratphoto

See my profile for my equipment
Click to expand...
--

Click to expand...
--
If you are a new user chances are good your question is answered in
the FAQ at:
http://www.marius.org/eos300dfaq.php

For a gallery of my photographs, see:
http://www.pbase.com/ratphoto

See my profile for my equipment
Click to expand...
--

 
I appreciate that in your first quick test you got "perfect WB" with a Pringles lid. Hey, stick with it if it works for you. It works for others too.

But, your posts suggest that you are still early in your learning about photography:
http://forums.dpreview.com/forums/read.asp?forum=1031&message=7987867
http://forums.dpreview.com/forums/read.asp?forum=1031&message=7986740

In the learning vein, perhaps you might sit back a bit on this one and read, reflect and learn a bit more about WB. Auto WB is pretty mediocre on the DR. Much as I love the camera, this is true. Read the review here and elsewhere. WB is especially poor with indoor lighting. Your post, suggesting that AWB is "excellent in all lighting & light temps that I've tried it in" suggests that you either haven't really tried it in a lot of different lightings OR you don't have a particularly critical eye YET about WB. If this is the case, you surely will develop it as you work with the camera.

The $100 for the ExpoDisc (or so) is a lot for an amateur, and the delta between it and a Pringles lid may not be so great in your eyes. But many pros swear by the thing, saying that it has changed the quality of their pictures and the speed of their workflow. Don't buy one until you feel you need it. I dismissed it completely until recently, and am still witholding complete judgement until I get it and test it. But I read a LOT about it on almost every pro forum and it seems excellent. And, I am at a point in MY photography where I feel I can learn a LOT from listening to pros and more knowledgable people.

Hey, it also might be helpful if you don't base your conclusions on ONE test that, by your own admission, is NOT reproducible. http://forums.dpreview.com/forums/read.asp?forum=1031&message=8071656 Any scientist knows that the first tenet of a "publishable" experiment is reproducibility. Anything less ranges from sloppy to fraudulent.
Mjack1957 said:
http://forums.dpreview.com/forums/read.asp?forum=1031&message=8071656
RATPhoto said:
I'm glad it is working for you but showing the tests shots would be
good (in the seperate thread you started).

--
If you are a new user chances are good your question is answered in
the FAQ at:
http://www.marius.org/eos300dfaq.php

For a gallery of my photographs, see:
http://www.pbase.com/ratphoto

See my profile for my equipment
Click to expand...
--

Click to expand...
--
Paul

------------------------------------------------
Pbase supporter
Photographs at: http://www.pbase.com/pbleic
--------------------------------------------------
Copyright 2003, 2004 All rights reserved.
 
I agree whole heartedly, but it still doesn't change the results.
pbleic said:
But, your posts suggest that you are still early in your learning
about photography:
http://forums.dpreview.com/forums/read.asp?forum=1031&message=7987867
http://forums.dpreview.com/forums/read.asp?forum=1031&message=7986740
In the learning vein, perhaps you might sit back a bit on this one
and read, reflect and learn a bit more about WB. Auto WB is pretty
mediocre on the DR. Much as I love the camera, this is true. Read
the review here and elsewhere. WB is especially poor with indoor
lighting. Your post, suggesting that AWB is "excellent in all
lighting & light temps that I've tried it in" suggests that you
either haven't really tried it in a lot of different lightings OR
you don't have a particularly critical eye YET about WB. If this
is the case, you surely will develop it as you work with the camera.

The $100 for the ExpoDisc (or so) is a lot for an amateur, and the
delta between it and a Pringles lid may not be so great in your
eyes. But many pros swear by the thing, saying that it has changed
the quality of their pictures and the speed of their workflow.
Don't buy one until you feel you need it. I dismissed it
completely until recently, and am still witholding complete
judgement until I get it and test it. But I read a LOT about it on
almost every pro forum and it seems excellent. And, I am at a point
in MY photography where I feel I can learn a LOT from listening to
pros and more knowledgable people.

Hey, it also might be helpful if you don't base your conclusions on
ONE test that, by your own admission, is NOT reproducible.

http://forums.dpreview.com/forums/read.asp?forum=1031&message=8071656 Any scientist knows that the first tenet of a "publishable" experiment is reproducibility. Anything less ranges from sloppy to fraudulent.
Mjack1957 said:
http://forums.dpreview.com/forums/read.asp?forum=1031&message=8071656
RATPhoto said:
I'm glad it is working for you but showing the tests shots would be
good (in the seperate thread you started).

--
If you are a new user chances are good your question is answered in
the FAQ at:
http://www.marius.org/eos300dfaq.php

For a gallery of my photographs, see:
http://www.pbase.com/ratphoto

See my profile for my equipment
Click to expand...
--

Click to expand...
--
Paul

------------------------------------------------
Pbase supporter
Photographs at: http://www.pbase.com/pbleic
--------------------------------------------------
Copyright 2003, 2004 All rights reserved.
Click to expand...
--

 
Cost of materials? Give Diane Wallace a call - she answers the phone there and is full of info. Apparently her Dad was just passionate about this thing because of his committment to the Zone system. Had an 18% price freeze and was charging less than it cost him to make the thing. When he died, she took it over, looked at the books and had to raise prices just to be able to keep the thing solvent. From what I understand the device uses plastic prism and then has an INDIVIDUALLY chosen mix of gel or something put inside to adjust the thing (using a colorimiter) to perfect mid-tone transmittance, across R, G, and B. From the aforementioned paper in BJ Photography (coming out in a few days) the adjustment is darn near perfect. And, it comes with a measurement of the individual device.

This sort of custom adjustment is what you are paying for - not the component parts.

Paul
Mark Marshall said:
pbleic said:
Not surprisingly, they have seen a little "spike" in sales over the
past week. We had a long and very interesting conversation,
followed by some emails from her. Some are quite interesting and I
will share them.

First, here is an email on testing the ExpoDisc by Kevin Kubota, a
very well known digital photography educator/digital photographer:
http://www.kubotaworkshops.com/pages/info.html

-----Original Message-----
From: Kevin Kubota [ [email protected]]
Sent: Sunday, March 14, 2004 9:46 PM
To: Diane Wallace; 'Laurie Love'; Chris Stocker; 'Erik and Erica
Sowder'
Cc: [email protected]; 'Mary T. Mannix'; Craig Strong
Subject: ExpoDisc vs. Pringles vs. AutoWB vs. Dirty Gym Socks

It's funny to see all the comparisons to the ExpoDisc. I've done a
few of my
own.

I used a Nikon D100 and a table lamp to test different WB methods. I
compared the ExpoDisc, the infamous Pringles lid, Auto White
Balance, and
Dirty Gym socks.

I tested by taking the first WB setting with ExpoDisc, brought it into
Photoshop CS and ran the AVERAGE filter to normalize any vignetting
and
stray pixels. The result is a even color field representing the
average
color cast - essentially a grey card. As expected the ExpoDisc
provided
PERFECTLY matching RGB values - indicating perfect WB.

Knowing that the ExpoDisc provides perfect WB, I then set the WB
using the
other methods, then shot a grey frame with the ExpoDisc over the
lens. I
brought all the frames into PS CS, ran the AVERAGE filter and noted
the
results with the eyedropper.

Here are the results and the .jpg files are attached.

ExpoDisc R:94 G:94 B:94
Pringles R:88 G:95 B:101 (too much blue cast)
AutoWB R:123 G:98 B:34 (very warm. Yikes! people actually trust
Auto?!)
Dirty Sock R:125 G:99 B:72 (Way off and smelly too)

Similarly off results are gained with coffee filters, panty hose,
garden
hoses, tracing paper, diffusion fabric, table cloths, dress socks,
frosted
glass, plastic grocery bags, and organic rice paper imported from
old world
Japan.

Besides, none of the above come with the cool little neck strap
dangly.

Aloha,
Kevin Kubota
Mark Marshall said:
----------------------------------> >
Click to expand...
Kubota Photo-Design, Inc.
Drake Award Winning website
See it: http://www.kkphoto-design.com
email: [email protected]
Cheap: (541) 330-6633
Free: (800) 738-2249
Fax: (541) 330-5540

--
Click to expand...
--
Enjoy life - spend your clothing budget on lenses
http://rhodeymark.instantlogic.com/PhotoGallery.ilx

Click to expand...
--
Paul

------------------------------------------------
Pbase supporter
Photographs at: http://www.pbase.com/pbleic
--------------------------------------------------
Copyright 2003, 2004 All rights reserved.
 
You said "it happened" ONCE. You said it isn't reproducible. You said it hasn't happened since. This is NO result. That was the point of the end of my post. If you continue to insist on this "result" it does begin to move from sloppy to deceptive.
Mjack1957 said:
pbleic said:
But, your posts suggest that you are still early in your learning
about photography:
http://forums.dpreview.com/forums/read.asp?forum=1031&message=7987867
http://forums.dpreview.com/forums/read.asp?forum=1031&message=7986740
In the learning vein, perhaps you might sit back a bit on this one
and read, reflect and learn a bit more about WB. Auto WB is pretty
mediocre on the DR. Much as I love the camera, this is true. Read
the review here and elsewhere. WB is especially poor with indoor
lighting. Your post, suggesting that AWB is "excellent in all
lighting & light temps that I've tried it in" suggests that you
either haven't really tried it in a lot of different lightings OR
you don't have a particularly critical eye YET about WB. If this
is the case, you surely will develop it as you work with the camera.

The $100 for the ExpoDisc (or so) is a lot for an amateur, and the
delta between it and a Pringles lid may not be so great in your
eyes. But many pros swear by the thing, saying that it has changed
the quality of their pictures and the speed of their workflow.
Don't buy one until you feel you need it. I dismissed it
completely until recently, and am still witholding complete
judgement until I get it and test it. But I read a LOT about it on
almost every pro forum and it seems excellent. And, I am at a point
in MY photography where I feel I can learn a LOT from listening to
pros and more knowledgable people.

Hey, it also might be helpful if you don't base your conclusions on
ONE test that, by your own admission, is NOT reproducible.

http://forums.dpreview.com/forums/read.asp?forum=1031&message=8071656 Any scientist knows that the first tenet of a "publishable" experiment is reproducibility. Anything less ranges from sloppy to fraudulent.
Mjack1957 said:
http://forums.dpreview.com/forums/read.asp?forum=1031&message=8071656
RATPhoto said:
I'm glad it is working for you but showing the tests shots would be
good (in the seperate thread you started).

--
If you are a new user chances are good your question is answered in
the FAQ at:
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Paul

------------------------------------------------
Pbase supporter
Photographs at: http://www.pbase.com/pbleic
--------------------------------------------------
Copyright 2003, 2004 All rights reserved.
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Paul

------------------------------------------------
Pbase supporter
Photographs at: http://www.pbase.com/pbleic
--------------------------------------------------
Copyright 2003, 2004 All rights reserved.
 
Final comment on this matter... life is just too short and filled with other more important issues. I made a comment of a factual experience. Sorry to offend anyone. Just take pictures and enyoy your day.

By the way... I don't lie or engage in deceptive practices. I'm not selling Pringles lids on the side. :)
pbleic said:
Mjack1957 said:
pbleic said:
But, your posts suggest that you are still early in your learning
about photography:
http://forums.dpreview.com/forums/read.asp?forum=1031&message=7987867
http://forums.dpreview.com/forums/read.asp?forum=1031&message=7986740
In the learning vein, perhaps you might sit back a bit on this one
and read, reflect and learn a bit more about WB. Auto WB is pretty
mediocre on the DR. Much as I love the camera, this is true. Read
the review here and elsewhere. WB is especially poor with indoor
lighting. Your post, suggesting that AWB is "excellent in all
lighting & light temps that I've tried it in" suggests that you
either haven't really tried it in a lot of different lightings OR
you don't have a particularly critical eye YET about WB. If this
is the case, you surely will develop it as you work with the camera.

The $100 for the ExpoDisc (or so) is a lot for an amateur, and the
delta between it and a Pringles lid may not be so great in your
eyes. But many pros swear by the thing, saying that it has changed
the quality of their pictures and the speed of their workflow.
Don't buy one until you feel you need it. I dismissed it
completely until recently, and am still witholding complete
judgement until I get it and test it. But I read a LOT about it on
almost every pro forum and it seems excellent. And, I am at a point
in MY photography where I feel I can learn a LOT from listening to
pros and more knowledgable people.

Hey, it also might be helpful if you don't base your conclusions on
ONE test that, by your own admission, is NOT reproducible.

http://forums.dpreview.com/forums/read.asp?forum=1031&message=8071656 Any scientist knows that the first tenet of a "publishable" experiment is reproducibility. Anything less ranges from sloppy to fraudulent.
Mjack1957 said:
http://forums.dpreview.com/forums/read.asp?forum=1031&message=8071656
RATPhoto said:
I'm glad it is working for you but showing the tests shots would be
good (in the seperate thread you started).

--
If you are a new user chances are good your question is answered in
the FAQ at:
http://www.marius.org/eos300dfaq.php

For a gallery of my photographs, see:
http://www.pbase.com/ratphoto

See my profile for my equipment
Click to expand...
--

Click to expand...
--
Paul

------------------------------------------------
Pbase supporter
Photographs at: http://www.pbase.com/pbleic
--------------------------------------------------
Copyright 2003, 2004 All rights reserved.
Click to expand...
--

Click to expand...
--
Paul

------------------------------------------------
Pbase supporter
Photographs at: http://www.pbase.com/pbleic
--------------------------------------------------
Copyright 2003, 2004 All rights reserved.
Click to expand...
--

 
Mark,

Let me jump in.
Mark Marshall said:
After going back and reacquainting myself with the website,
something you said just struck me. Why would the sizes be jacked up
to such a premium (my largest lens is 82mm now) if the reading is
done from the center only? I always figured filters are priced
accordingly because they are expected to work consistently all the
way to the edges. ~ m²
Click to expand...
What I would say is that, if we aren't concerned with luminance measurement (incident light measurement) use, but only WB measurement, I would guess that a smaller diffuser would do fine.

I haven't really thought out all the wrinkes in incident light measurement.

But I spared no expense - I cut the two circles of filter packing foam to the full size of the glass in my 58 mm filter rings!

Best regards,

Doug
 
With this approach to reporting results, any further "testing" from you on any topic wouldn't be particularly helpful.

Deception in reporting of results doesn't necessarily mean you have are biased by money. It means that you are not reporting your results accurately, on purpose. This can be for many reasons, including just plain ego, or an unwillingness to consider the possibility that one is wrong.

When reporting testing results, it is DECPTIVE to report a "perfect" result alone, without mentioning that every retest failed to achieve this same result (until you are pushed to say this). And then to continue to claim that your result was the unreproducible one. Deceptive; no other word for it.
Mjack1957 said:
By the way... I don't lie or engage in deceptive practices. I'm
not selling Pringles lids on the side. :)
pbleic said:
Mjack1957 said:
pbleic said:
But, your posts suggest that you are still early in your learning
about photography:
http://forums.dpreview.com/forums/read.asp?forum=1031&message=7987867
http://forums.dpreview.com/forums/read.asp?forum=1031&message=7986740
In the learning vein, perhaps you might sit back a bit on this one
and read, reflect and learn a bit more about WB. Auto WB is pretty
mediocre on the DR. Much as I love the camera, this is true. Read
the review here and elsewhere. WB is especially poor with indoor
lighting. Your post, suggesting that AWB is "excellent in all
lighting & light temps that I've tried it in" suggests that you
either haven't really tried it in a lot of different lightings OR
you don't have a particularly critical eye YET about WB. If this
is the case, you surely will develop it as you work with the camera.

The $100 for the ExpoDisc (or so) is a lot for an amateur, and the
delta between it and a Pringles lid may not be so great in your
eyes. But many pros swear by the thing, saying that it has changed
the quality of their pictures and the speed of their workflow.
Don't buy one until you feel you need it. I dismissed it
completely until recently, and am still witholding complete
judgement until I get it and test it. But I read a LOT about it on
almost every pro forum and it seems excellent. And, I am at a point
in MY photography where I feel I can learn a LOT from listening to
pros and more knowledgable people.

Hey, it also might be helpful if you don't base your conclusions on
ONE test that, by your own admission, is NOT reproducible.

http://forums.dpreview.com/forums/read.asp?forum=1031&message=8071656 Any scientist knows that the first tenet of a "publishable" experiment is reproducibility. Anything less ranges from sloppy to fraudulent.
Mjack1957 said:
http://forums.dpreview.com/forums/read.asp?forum=1031&message=8071656
RATPhoto said:
I'm glad it is working for you but showing the tests shots would be
good (in the seperate thread you started).

--
If you are a new user chances are good your question is answered in
the FAQ at:
http://www.marius.org/eos300dfaq.php

For a gallery of my photographs, see:
http://www.pbase.com/ratphoto

See my profile for my equipment
Click to expand...
--

Click to expand...
--
Paul

------------------------------------------------
Pbase supporter
Photographs at: http://www.pbase.com/pbleic
--------------------------------------------------
Copyright 2003, 2004 All rights reserved.
Click to expand...
--

Click to expand...
--
Paul

------------------------------------------------
Pbase supporter
Photographs at: http://www.pbase.com/pbleic
--------------------------------------------------
Copyright 2003, 2004 All rights reserved.
Click to expand...
--

Click to expand...
--
Paul

------------------------------------------------
Pbase supporter
Photographs at: http://www.pbase.com/pbleic
--------------------------------------------------
Copyright 2003, 2004 All rights reserved.
 
There appears to be a mis-communicated aspect to using ExpoDiscs, Pringles lids, grey/gray cards or indeed any other device for setting WB. This mis-communication may lead to confusion, inaccurate testing and general mis-understanding of the WB process and associated tools.

It is often commented by some that they are testing these devices by comparing the RGB values of the resulting shot taken with the device in question. E.g. you see references to R 128, G 128 and B 128 and similar.

My understanding is that these tests are pretty useless by themselves (unless they are taken in perfect white light, equally balanced in all 3 channels, that has been tested with proper equipment).

Neither an ExpoDisc nor a Pringles lid (which seem to be the most preferred methods in these forums) - nor even the "holy grail" gray/grey card - will give you exactly the same RGB values under each set of shooting conditions.

This is the point of a reference WB device: it shows you (or more to the point, the camera or the hardware/software tool you use afterwards to process the shot) in which way the scene's lighting was off from a 'true' WB. This allows you to correct the colour cast and develop the shot as it looked to the human eye (which automatically corrects for WB).

Thus if under tungsten lighting your device shows a perfectly uniform distribution of RGB (say 112, 112 and 112) this does not indicate a great WB device. Far from it! A decent WB device would show the light as having the characteristic orange tint associated with tungsten lighting (higher in Red channel, lower in Blue), quantifying it correctly and then allowing you to compensate correctly for it, giving you a decent true colour rendition.

Of course, once you select the original WB device shot as your reference, then the hardware or software you are using will automatically adjust the values to match. That is the point. Continuing the earlier tungsten example, the following shots will be therefore adjusted down in the Red and up in the Blue channels to compensate for the orange effect, giving your truer colours.

Having played with an ExpoDisc in recent weeks has given me a much better understanding of this process and the failings (for me) of some of the other systems. For example, a Pringles lid doesn't do it for me (it has a faint, but noticeable to me, blue cast) - perhaps that's just the lid in the UK, in the US it may well be different.

I'm not going join in the religious war between different WB systems. Everyone has to find or choose the appropriate method that suits their needs and style the best. For me, it was an ExpoDisc, but for someone else it may well be a coffee filter.

Lastly, it's also worth pointing out that the absolute RGB values themselves are irrelevant to the WB settings, it is only the relative values that are important. Hence why you can set WB with a grey card, a piece of "white" paper (don't get me started on the different casts of white paper) or a grey between these two. As long as none of the RGB channels are blownout - giving incorrect relative values - these should all work.

The absolute values serve simply to show the exposure levels for the incident or reflective light at the time of the shot, e.g. RGB values of 80,80,80 are underexposed compared to RGB values of 128,128,128 - but the WB properties (the relative ratio between these channels) are the same.

I'm certain that someone with a deeper understanding of this will be able to correct me if I've made a mistake, or add to this overview.

Phew, that was longer than intended, but I hope it helps.

Jason.
 
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