White balance and exposure determination

[Bart_van_der_Wolf]

Another plus is that it brought to my attention PhotoBola's Raw Image Analysis tool (Rawnalyze). That is way neat, and very helpful in the areas we have been discussing.

Rawnalyser is a very useful tool. It e.g. allows to accurately decide which exposure from a bracketed sequence is the optimal (ETTR) exposure, based on the Raw data. My 1Ds3 starts to warn (blinking LCD) 1/2 stop before actual clipping. The most underexposed channel may benefit from such an exosure increase.

However, don't forget that a given Raw converter may not be anticipating perfect exposures when the predetermined camera profile is optimized for someting else (e.g. per channel noise reduction based on known underexposure). A good Rawconverter shouldn't assume stuff based on camera model, but rather determine based on the actual image content, but there is no guarantee that they all do that.

In-camera White Balancing doesn't help much, although I understand why Drew promotes it ...

Bart

 

[Asher Kelman]

Rawnalyser is a very useful tool. It e.g. allows to accurately decide which exposure from a bracketed sequence is the optimal (ETTR) exposure, based on the Raw data. My 1Ds3 starts to warn (blinking LCD) 1/2 stop before actual clipping. The most underexposed channel may benefit from such an exosure increase.

Bart,

Is Rawanylser the only such tool? I'd like a Mac software. Better still a color lightmeter, then know what filter to add.

Asher

 

[Doug Kerr]

Hi, Asher,

Better still a color lightmeter, then know what filter to add.

Well, there are certainly color photometers readily available.

I'm not sure that how to apply the readings of such a meter to the choice of a "pre-filter" is readily known. (There was a discussion of some of the challenges in the choice of a pre-filter in the Luminous Landscape thread that was cited here recently.)

Remember, the objective here is not to perform white balance color correction through the use of the filter (as would have been the case in film practice) but rather to equalize the range of primary exposure result over the three subsets of sensels, so as to allow an exposure choice that will optimize noise performance over all three "channels". ("Primary exposure result" is my term for the digital result, out of the sensel reading system, of the photometric exposure on the sensels - essentially a synonym for the raw output data.)

Best regards,

Doug

 

[Bart_van_der_Wolf]

Is Rawanylser the only such tool? I'd like a Mac software. Better still a color lightmeter, then know what filter to add.

AFAIK I'm afraid it is the only one around. I have no idea if it runs well under Parallels or other virtualization software, but since it's one executable file, it probably does.

The problem with color light meters (like the old Minolta one) is that they are calibrated towards film spectral sensitivity curves. Sekonic has one with also a typical CFA response, although it might still be somewhat different from the actual CFA filters used in one's specific camera.

Bart

 

[Asher Kelman]

The problem with color light meters (like the old Minolta one) is that they are calibrated towards film spectral sensitivity curves. Sekonic has one with also a typical CFA response, although it might still be somewhat different from the actual CFA filters used in one's specific camera.

Bart,

That looks promising. The radio triggers; can they be matched to Elinchrom or are they specific for Pocket Wizards? I wonder if the Elinchrom has a "learning mode" like the TV remotes?

Asher