Color temperature difference between film and digital?

[connloyalist]

First of all, not sure this is the right place for this question. Second, this is a question out of curiosity, I don't have a stake in the outcome.

The other day I came across the following:

https://crawfordphotoschool.com/shooting-techniques/color-meters-1.php

where on that and the next few pages the author appears to say that color temperature in kelvin is or should be applied somewhat differently depending whether you are using film or digital. See for example page 3 of that article where it is shown that the Sekonic C-700 (which I don't own) has modes for digital and film that give slightly different readings of color temperature.

Why would this be so? I can imagine types and brands of film stock behaving differently from each other, but for the same measure I would not be surprised if different digital sensors have slightly varying behaviors to color temperature. So why specifically digital versus film? Perhaps related to digital being linear 0-255 and film / analog having non-linear behavior?

To be clear, I don't need a device that gives me color temperature. For me this is strictly intellectual curiosity.

Regards, C.

[RokkorDoctor]

I would imagine that the combination of the colour filters used on digital sensors + the photosites themselves have a different spectral response characteristic than that of traditional colour film. The film vs digital mode on some of those colour meters will probably partly correct for that difference as the colour temperature of the illumination changes.

This correction may be even more important when the light source is not pure black-body radiation, but spectral in nature, which these days it often is with CFL and LED light sources.

But I agree with you; whilst a film/digital mode setting may be able to address this partially, I would imagine that in reality colour correction would very much be dependent on both the specific spectral nature of the illumination as well as the spectral response characteristic of the specific maker's and model sensor. Not much different really from some scanners coming with canned colour profiles for colour film vs reversal(slide) film whereas really what you would need is maker, model, and ideally batch-specific profiles.

To be honest, with digital cameras these days offering in-camera white-balance calibration given a neutral test-target, I struggle to see the major value of a colour meter these days unless you are still shooting both film & digital and are looking for best colour consistency across both.

In practice I find all this a bit pointless anyway given the metamerism problems displayed of so many surfaces, paints & dyes under spectral LED lighting. Even LED lighting with a very high CRI is no guarantee for colour matching given the inappropriately small number of colour swatches used in determining a LED's CRI rating. Hence I tend to adjust to something that looks good rather than try to get to an impossible to achieve consistent "exact" colour rendition. I mean, what is the "correct" colour rendition of an Alexandrite gemstone???, a very similar problem really.

[D1N0]

I don't see much use for colour meters when shooting film unless you can control your light source with filters, like in a studio. For digital maybe but you can also use your camera for that. Maybe it is more accurate, but accurate is not what your eyes see anyway. They always adjust a bit to a less extreme value. My camera adjusts in increments of 50 kelvin. green/magenta in increments of 1 whatever scale is used for that.

[visualopsins]

Would be of interest to see comparison of color meter reading of white card and custom wb setting camera uses when set for photo of white card, and wb setting of software when white card in frame is chosen as reference. I seem to get best wb with the last method.

[cooltouch]

Well, in terms of intellectual curiosity only, I was taught many years ago that the color temperature of the sun is 5600 k and that the color temp of your average studio incandescent flood was 3200 k.

I owned a Gossen color meter for a while, but I never used it except for playing around with it on occasion. It was a pretty cool unit. I ended up selling it to a friend who just had to have it.

Back in my film days, probably 90% or better of my photography was done outdoors, so I didn't feel much of a need to pay attention to the color temperature of a scene. Hey, if it was late in the afternoon or early in the morning, where the color temp was lower, I just included that "feature" as part of the ambiance.

[visualopsins]

Camera set to "Daylight" WB can also show color rendition differences among lenses; essentially equivalent to using Daylight film.