Doug Kerr
Well-known member
A new article by Sara Frances, M.Photog.CR., "An Investment in White Balance that Appreciates Right Now", has recently been posted on the Pro Photo Reviews and Articles section of the Pro Photo Home forum. In the article, Frances discusses the need for attention to white balance matters, gives a checklist to guide those taking steps in this direction, and in a chart, lists 10 white balance tools and gives them a "color neutrality rating" on a scale of 1-5.
The article can be viewed here:
http://www.prophotohome.com/forum/p...ment-white-balance-appreciates-right-now.html
Before I comment further, let me mention two terms used in the descriptions of the tools' applicability, "incident WB" and "reflectant WB".
We often see the terms "incident" and "reflective" used (inappropriately) for the distinction between making a white balance measurement, using a "diffuser" on the camera lens, at the subject location vs at the camera location for actual shooting.
But that cannot always be be the distinction intended by Frances, since she also applies it in the case of such things as white balance targets. In those cases, she likely means measurements made from a reflective target. In other cases (for diffuser tools), it apparently means "reflective" in the sense described above.
That having been said, let's look at the comparison chart. The tools are divided into three categories: Disks, Targets, and Cards. The "disks" listed include the Colorright [sic], CBL (Color Balance Lens), ClearWhite, and ExpoDisk.
The common element of the "Disks" is that they are round. It may seem trite to mention that, but I must in order to emphasize that this is the only common factor - they are not of a common functionality. Three of them are used in front of the camera lens (as a "measurement diffuser"). But one of them, the CBL, is, despite its name, a target disk, a fairly high reflectance "white" on one side and a "neutral" gray on the other side.
Incidentally, it is hard to find this out this basic fact from the extensive pseudo-scientific material on the CBL manufacturer's Web site - nowhere does it give the slightest hint as to how to use the device. (Frances quite accurately says that "the booklet and website [are] extensive but difficult to understand".)
In any case, Frances must have figured out how to use it, since she includes an brief assessment of its performance in her table: ". . . excellent result placed anywhere, any angle in incident light, consistent in many circumstances."
For the Colorright [sic] disk, she says: "optimal use incident, fair to good reflectant - best of all devices under green leaves". Here, she apparently uses "reflectant" to refer to the so-called "reflective" technique for measurement with a diffuser, in which the diffuser-equipped camera is placed and aimed as it will be for the actual shot.
Overall, she gives the Colorright, CBL, and ClearWhite (a simple milk-white acrylic diffuser) color neutrality ratings of 5, while the ExpoDisk (also a diffuser) gets a 4.
We have no hint as to how the ExpoDisk fell short. It is described as "medium consistent in varying situations". Perhaps this is a reference to the fact that it cannot be expected to perform well in the "from the camera position" ("reflective") mode, for which it is not designed, and whose use is not recommended by its manufacturer.
In fact, nowhere in the article is there the slightest hint of how the testing was done (the author reports it as "per my 6-month on the job testing"), nor what criteria were used in assessing the performance of the different tools and the assignment of color neutrality ratings.
I won't go into any detail on the "Targets" and "Cards" sections of the chart (the distinction between the two seeming to be pretty arbitrary). All of these items received an color neutrality rating of 4 (the apparent scale of 1-5) except for a random piece of Styrofoam packing (reported in the "Cards" section), which was given a color neutrality rating of 3.
Frances comments that this is "better than coffee filters or plastic caps", and lists its disadvantages as "crumbles easily, non-traveling".
Evidently based on the ColorRight tool receiving a color neutrality rating of 5 on the Frances scale (along with the CBL thing and the ClearWhite diffuser), the manufacturer of the ColorRight announced, "COLORRIGHT Ranks Tops out of 10 White Balance Products in New Pro Review".
I conclude with this equation from the autobiography of the author that appears at the end of the article: "I’ve spent my whole career working very hard to make what I do appear effortless." Sara, I think you have succeeded.
**************
Since it figures into this story, let me take a moment to return to the CBL (Color Balance Lens), a truly curious item. Its front face is (apparently) opaque white plastic, into which are molded a number of short straight "ridges" of various cross sections. These are said to give the device its superior properties with regard to acceptance of light. It may well be that the purpose is to attain a nearly Lambertian response to light arriving from differetn angles.
In any case, the entire device is manifestly opaque (since the rear face is opaque gray plastic).
The gray rear face used to be thought of as just the back of the device, in which a product "description" is molded, but they later realized that it was a neutral gray target.
It is interesting that on the CBL manufacturer's Web site, despite the presence of a profusely-illustrated 18 page "Product Training Manual", full of pseudo-scientific jargon, nowhere is there the slightest mention of how one uses the device. I have assumed that, since it is opaque, the intent is for it to be used as a reflective target.
**************
Well, that's the color science report for today.
The article can be viewed here:
http://www.prophotohome.com/forum/p...ment-white-balance-appreciates-right-now.html
Before I comment further, let me mention two terms used in the descriptions of the tools' applicability, "incident WB" and "reflectant WB".
We often see the terms "incident" and "reflective" used (inappropriately) for the distinction between making a white balance measurement, using a "diffuser" on the camera lens, at the subject location vs at the camera location for actual shooting.
But that cannot always be be the distinction intended by Frances, since she also applies it in the case of such things as white balance targets. In those cases, she likely means measurements made from a reflective target. In other cases (for diffuser tools), it apparently means "reflective" in the sense described above.
That having been said, let's look at the comparison chart. The tools are divided into three categories: Disks, Targets, and Cards. The "disks" listed include the Colorright [sic], CBL (Color Balance Lens), ClearWhite, and ExpoDisk.
The common element of the "Disks" is that they are round. It may seem trite to mention that, but I must in order to emphasize that this is the only common factor - they are not of a common functionality. Three of them are used in front of the camera lens (as a "measurement diffuser"). But one of them, the CBL, is, despite its name, a target disk, a fairly high reflectance "white" on one side and a "neutral" gray on the other side.
Incidentally, it is hard to find this out this basic fact from the extensive pseudo-scientific material on the CBL manufacturer's Web site - nowhere does it give the slightest hint as to how to use the device. (Frances quite accurately says that "the booklet and website [are] extensive but difficult to understand".)
In any case, Frances must have figured out how to use it, since she includes an brief assessment of its performance in her table: ". . . excellent result placed anywhere, any angle in incident light, consistent in many circumstances."
For the Colorright [sic] disk, she says: "optimal use incident, fair to good reflectant - best of all devices under green leaves". Here, she apparently uses "reflectant" to refer to the so-called "reflective" technique for measurement with a diffuser, in which the diffuser-equipped camera is placed and aimed as it will be for the actual shot.
Overall, she gives the Colorright, CBL, and ClearWhite (a simple milk-white acrylic diffuser) color neutrality ratings of 5, while the ExpoDisk (also a diffuser) gets a 4.
We have no hint as to how the ExpoDisk fell short. It is described as "medium consistent in varying situations". Perhaps this is a reference to the fact that it cannot be expected to perform well in the "from the camera position" ("reflective") mode, for which it is not designed, and whose use is not recommended by its manufacturer.
In fact, nowhere in the article is there the slightest hint of how the testing was done (the author reports it as "per my 6-month on the job testing"), nor what criteria were used in assessing the performance of the different tools and the assignment of color neutrality ratings.
I won't go into any detail on the "Targets" and "Cards" sections of the chart (the distinction between the two seeming to be pretty arbitrary). All of these items received an color neutrality rating of 4 (the apparent scale of 1-5) except for a random piece of Styrofoam packing (reported in the "Cards" section), which was given a color neutrality rating of 3.
Frances comments that this is "better than coffee filters or plastic caps", and lists its disadvantages as "crumbles easily, non-traveling".
Evidently based on the ColorRight tool receiving a color neutrality rating of 5 on the Frances scale (along with the CBL thing and the ClearWhite diffuser), the manufacturer of the ColorRight announced, "COLORRIGHT Ranks Tops out of 10 White Balance Products in New Pro Review".
I conclude with this equation from the autobiography of the author that appears at the end of the article: "I’ve spent my whole career working very hard to make what I do appear effortless." Sara, I think you have succeeded.
**************
Since it figures into this story, let me take a moment to return to the CBL (Color Balance Lens), a truly curious item. Its front face is (apparently) opaque white plastic, into which are molded a number of short straight "ridges" of various cross sections. These are said to give the device its superior properties with regard to acceptance of light. It may well be that the purpose is to attain a nearly Lambertian response to light arriving from differetn angles.
In any case, the entire device is manifestly opaque (since the rear face is opaque gray plastic).
The gray rear face used to be thought of as just the back of the device, in which a product "description" is molded, but they later realized that it was a neutral gray target.
It is interesting that on the CBL manufacturer's Web site, despite the presence of a profusely-illustrated 18 page "Product Training Manual", full of pseudo-scientific jargon, nowhere is there the slightest mention of how one uses the device. I have assumed that, since it is opaque, the intent is for it to be used as a reflective target.
**************
Well, that's the color science report for today.
Last edited:
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