All of the info I have seen on the web, including Miachel's, use the Passport with a single illuminant to make a "scene" profile. But it can also be used with a dual illuminant to make a default camera profile. I have used it in both ways and below are my observations about it -- Lightroom 3 beta and Canon 5D2:
Even when using a single illuminant for a scene profile, you must set the white balance in Lightroom.
My initial single illuminant tests used both the Passport and a WhiBal card in the same scene. The objective was to determine if the same or better results could be obtained with just the WhiBal. I made three different tests in tungsten light:
1. Scene profile with Passport and setting White Balance in Lightroom
2. Just using the Passport white balance square to set white balance in Lightroom with Adobe Standard camera profile.
3. Using the WhiBal to set white balance in Lightroom with Adobe Standard.
The rankings were 1, 2, 3. 1 produced results that were so good that they were surprising.
The initial jusdements were made by viewing the results side by side in Lighrom using the shot of the Passport and WhiBal. The final judgement was made by comparing the results on actual subjects that included people.
2 and 3 were close, but 2 was better than 3.
The work flow problems with making individual scene profifles are the time to make the profile for the scene and to get it into Lightroom. Then there is the problem of the great number of profiles on the system if you do this a lot. Remember, you can't delete that profile if you want it available for future work on that file(s).
Using the Dual illuminant profile, you make what could be called a default camera profile, like Adobe Standard, etc. I decided to try that. It takes two files and it is suggsted to take them with greatly different light sources.
I used a sunlight shot with the sun high overhead and no clouds in Costa Rica. I used the same tungsten shot for the tests for the single illuminant, above.
Comparing the results between this default profile and Adobe Standard, the profile from the Passport was as surprisingly good as the results in the single illumionate tests. The colors in a shot of red flowers with green foliage, green grass, blue sky and caucasian skin were much improved when compared to Adobe Standard.
1. I have set the dual illuminant profile as a user preset and will use it when importing into Lightroom with 5D2.
2. I shoot the Passport when light conditions change and use the white balance square to set white balance -- like I did with the WhiBal.
3. Since I have the Passport shot, I make scene profiles when the importance and circumstances of the shot warrant if.
4. My overall conclusion is that this is one of the best tools I have used.