White Balance - Adjust via RGB histogram

tonylong wrote in post #11746455
Which brings us back to this! Those greys are all over the map -- anybody got a good reliable gray card that doesn't require guesswork?

The Whibal is the only one that's calibrated. I used those images to show how far off everything can be, including gray cards.

If gray cards don't match, then how could anyone expect plan paper to be accurate.

The Whibal looks the closest to an advertised reading. I used the cameras meter to set EV and not my meter, so it could be causing numbers to move.
The walls in the room are a Darkish Pastel Blue.

I'll test them in the studio tomorrow and see what happens

Sorry, I wasn't referring to the White Balance, should have made that clear -- I was referring to the fact that many have found a need to add some EV to the 18% gray card and I've found similar things, like to using the Sunny 16 rule you may need to add +2/3 EV. I have my own method for shooting various things, but the discrepancy with both the 18% gray card and the Sunny 16 rule tend to rattle in my brain when it comes to discussions about using them for exposure.

No biggy because we can all use the chimping and adjusting the EV and such, but it's an interesting subject.

tonylong wrote in post #11746740
Sorry, I wasn't referring to the White Balance, should have made that clear -- I was referring to the fact that many have found a need to add some EV to the 18% gray card and I've found similar things, like to using the Sunny 16 rule you may need to add +2/3 EV. I have my own method for shooting various things, but the discrepancy with both the 18% gray card and the Sunny 16 rule tend to rattle in my brain when it comes to discussions about using them for exposure.

No biggy because we can all use the chimping and adjusting the EV and such, but it's an interesting subject.

Oh, OK. That's why I like the Photo Vision EV target.
I use it to set the EV just before it clips to maximize data capture I also use my Color Checker to set EV just before clipping.

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Tony, regarding exposure, the way we approach it should have changed in the digital era because it is a very different medium from film, but we still maintain old practices that have now become "urban myths" passed from generation to generation. It was not film that was calibrated to 18% grey; it was the film + development (time + temperature). If we gave a particular exposure to an 18% target and developed with the manufacturer's recommendation, the density of the negative would be in the center of the density curve and the values above and below would fall into place. But even this system didn't come into being until the introduction of panchromatic roll film in the '30s-'40s. Before that photographers developed orthochromatic sheet film in open trays by red light and simply pulled the film out when, according to their experienced eye, it looked right. And their exposures were based on the knowledge of how they could develop the film. But once they had to turn off the safe light, standardization became essential. It is said that Ansel Adams argued with Kodak about setting the 18% target as the fixed point upon which the development was based, but 18% was a good choice because it left foot-room for several stops of shadow density above the threshold exposure and the long gentle roll-off at the shoulder left a lot of wiggle room during printing for burning in highlights. Digital is essentially different, especially in-camera jpgs. Because there is no highlight roll-off but rather an abrupt highlight saturation point, camera makers calibrate the exposure>RAW>jpg closed system to 12-13% in order to leave a bit more of a safety margin before clipping. But we continue to use 18% cards or the Sunny 16 rule (based on the assumption of an 18% standard) without being aware, for the most part, of this. On the other hand, RAW shooting has, in effect, returned us to the days of open tray control of the development and we can base our exposures on our knowledge of what is possible during development, e.g. expose to the right.

Yeah, Elie, we do have to try to veer away from the "old ways" as some kind of standard. I veer between some "rule of thumb" stuff, like manually exposing a clear blue sky as +2/3 Ev (coming out brighter than "Sunny 16") and exposing to the right, and then on-the-fly shooting in Av in dim light.