The missing link - what white balance tool?

A month or two ago, in another forum, a member gave a link to the site of a manufacturer of a white balance measurement "tool" (a diffuser for use on the lens) with which I was not previously familiar.

It was neither the ExpoDisc nor the CBL.

Somehow I have the feeling that either the company or product name involved the letter "Q" (but I'm an old guy, and sometimes these things come to me in my dreams!).

Their site gave some nice polar plots of directivity, variation in chromatic response with angle, and so forth.

I neglected to capture the URL, and it has now apparently scrolled off the end of my browser's history log.

Does anyone recognize what I am thinking of here?

Thanks.

CBL

Sort of related...At the Wedding Class I recently took, I had a chance to work with the CBL disk. My teacher, recommended it highly so I went to the WPPI trade show and tried to buy it from two different vendors. Neither were carrying it - Samy's was one of the vendors and was actually negative about why. I went back to the booth for the Mfg. and they were'nt selling it and sent me to Samy's to buy it.

So I still don't have one. I do have the gray card spring loaded three color with small reflector on the reverse (I can't think of the brand). What a pain. I went to WPPI mostly to shop, network and take classes.

Hi Kathy,

I have tested the CBL and in fact, the "mirrored" side works quite well. But the other "Gray side" is not even close to being neutral.


But at the same time, I cannot see anything that the CBL "good side" does, that the WhiBal does not, at about 1/4 the price. And as you do, I find the spring loaded "targets" to be a PITA, and many of them are not even neutral, or vary from run to run.

Cavetat...As you may know I am the designer of WhiBal.

Hi, Michael,

Michael Tapes said:

I have tested the CBL and in fact, the "mirrored" side works quite well. But the other "Gray side" is not even close to being neutral.

Click to expand...

I'm not sure I understand the concept behind the front ("prismatic") side of the CBL target. Do you have any idea what tree it barks up? I have read the "manual" and, although it tosses about a lot of technical terms and concepts, actually gives no insight into how the thing is really supposed to work.

http://www.internationalsupplies.com/cbl/CBL_Product_Training_Manual_0307.pdf

It is tempting to ascribe the "lack of explanation" to a very bad translation of the original language (Korean?), but the lack transcends language difficulties. One might even cynically think that the bad translation is intended to obscure the lack of content.

From its name, I first thought this might be a transmissive diffuser.

Curious!

No, I do not plan to do any testing with one.

Best regards,

Doug

Thanks Michael for the info. I will check it out.

Doug_Kerr said:

Hi, Michael,

I'm not sure I understand the concept behind the front ("prismatic") side of the CBL target. Do you have any idea what tree it barks up? Doug

Click to expand...

I have no idea, and no one that I have spoken to has been able to help. But I did test it to do an In-camera WB and it was spot on, same as the WhiBal, and the CP and ED did not do so well. Order of performance was:

1 - Tie - WhiBal and CBL (both perfect as one would expect).
3 - ExpoDisk - (aimed at scene). Result not so good...as one would expect as I intentionally used it improperly.
4 - Color Parrot (V1.0) - Worse of the lot, also aimed at the scene, which they claim should work.

But given the pricing...
WhiBal = $36.95 (Studio Version for in-camera WB)
ExpoDisc = ~$90 (Dependant on size)
CP = $79.
CBL = ~$119 (Dependant on size)

Hi, Michael,

Michael Tapes said:

I have no idea, and no one that I have spoken to has been able to help. But I did test it to do an In-camera WB and it was spot on, same as the WhiBal, and the CP and ED did not do so well. Order of performance was:

1 - Tie - WhiBal and CBL (both perfect as one would expect).
3 - ExpoDisk - (aimed at scene). Result not so good...as one would expect as I intentionally used it improperly.
4 - Color Parrot (V1.0) - Worse of the lot, also aimed at the scene, which they claim should work.

Click to expand...

Thanks for the report. Not at all surprising (of course I had no prior idea about the CBL).

Best regards,

Doug

Doug_Kerr said:

I'm not sure I understand the concept behind the front ("prismatic") side of the CBL target.

Click to expand...

My speculation is that it picks up more 'sky-light' and ambient light incident on the subject from a wider angle (wider than Cosine/Lambertian), which reduces the influence of the photographer's reflected color. That speculation however is not based on personal knowledge of the specular reflectivity of the CBL's material, but on what I'd try out if I wanted to design such an object (say a refelective Fresnell surface of sorts).

That's why I use a WhiBal or Babelcolor target tilted up by 45 degrees at arms length (when I can't measure at the subjects position), to avoid getting my blue jeans reflection to play too large a part in ambient light falling on the target, and also because usually most light comes from above.

Bart

Hi, Bart,

Bart_van_der_Wolf said:

My speculation is that it picks up more 'sky-light' and ambient light incident on the subject from a wider angle (wider than Cosine/Lambertian), which reduces the influence of the photographer's reflected color. That speculation however is not based on personal knowledge of the specular reflectivity of the CBL's material, but on what I'd try out if I wanted to design such an object (say a refelective Fresnell surface of sorts).

Click to expand...

An interesting proposition.

Still, since the subject surface (if it is Lambertian, and if it isn't, it would be hard to predict how to handle it), it responds in a "cosine" way, so making a wider-than-cosine diffuser might be a little "out-thinking the situation".

My guess is that the front is covered with fairy dust (just as the back is made of a "secret ingredient" (per the promotional literature).

That's why I use a WhiBal or Babelcolor target tilted up by 45 degrees at arms length (when I can't measure at the subjects position), to avoid getting my blue jeans reflection to play too large a part in ambient light falling on the target, and also because usually most light comes from above.

Click to expand...

Certainly makes sense in that situation.

I have found that when aiming an ExpoDisk just barely over Carla's shoulder, it seems to pick up some of the light from her red sweater (which has some upward-facing surfaces when occupied). (That is, I get a "cooler" corrected output that when, for example, I put the camera with the EdpoDisk in front of her waist).

We know from watching movies about fashion photographers that the best way to measure the incident light illuminance for exposure purposes is to put your Norwood Director meter in the model's cleavage!

Best regards,

Doug