How to choose between a Grey Card, Expo Disk or Light Meter?

[unpopular]

...........Because white balance is determined at processing, not at the time of exposure, there isn't any need to be super precise about white balance either.

That's assuming everyone has all the time in the world to spend pushing a mouse around setting white balance to a file full of raws. Not everyone has that luxury.

Perhaps. But every camera has a custom white balance which works fairly well against a white reference, like a sheet of paper. This gets you pretty close, and will be similar for the an entire set.

Honestly, i don't understand all this white balance madness. Most professional photographers didn't even own a full set of CC filters and a color meter with film. They chose the right film for the situation and maybe an FL filter. For 99.9% of applications, the built-in color meter will do just fine so long as you don't rely on "auto" mode.

 

[Helen B]

It definitely would, but you don't normally point incident meters are the subject except in certain situations. You point it back at the camera.

Incident meters are designed to measure available light, not reflected light. But without a domed surface, it's not going to be very good at this either.

The Expodisk never made sense to me either.

I remember the Expodisk as being introduced as an incident attachment for cameras with TTL meters - hence the name. Only later was it sold as a white balance device. Like you say, it isn't as good as a domed receptor - there's a good reason why the incident diffuser on light meters has a non-flat shape. The idea is that for almost all purposes the best form of incident metering is to point the meter at the camera (or where the camera will be), and use the shape of the incident dome to read light from the sides and some from the rear, but not directly behind, as well as the light from the front (orientations with respect to the meter). Hence the cardioid response designed in to the dome or invercone.

Flat receptors, with a cosine response, are usually only used in studio situations to measure individual lights or the illumination of a flat object, but a shielded dome works just as well in that case (either designed in to the meter like many Sekonics, or shielded by your cupped hand). That's also why colour meters always have flat receptors - they are designed for measuring a source, not for measuring the average.

If you want to do incident metering with a TTL meter, just meter off the palm of your hand. It's a good, constant reference. For white balance there are plenty of things that are cheaper, faster and more convenient to use than an Expodisk. Except in the studio, my personal preference is to use a white reference and then set the WB for the whole batch in Lightroom.

 

[Tee]

I have a combo collapsable grey/white disc. On scene, I set my white balance using the white side then have the model flip the card around and take a shot of her holding the grey side for post production (if needed). Takes about 20-30 seconds for the whole process and has worked well. The expo disc has always appeared "gimmicky" in my opinion especially when there are cheaper options that provide the same results.