Actual dynamic range of any camera vs stated

[Patrick Pitre]

Hopefully someone here can help me understand this better. A given camera will state that it has X amount of dynamic range. For example, my Canon 5D Mark III has 10 stops of dynamic range. An Arri Alexa has 14 stops of dynamic range. Film (e.g., Kodak Vision 3 500T) is said to have about 14 stops of dynamic range as well.

However, there’s no way I can actually capture anywhere near 14+ stops of dynamic range in any given image. Even HDR (stills or video) only gives me a few extra stops up or down (and if abused, saccharine images!). For my still photography, I mostly use the Zone system and spot metering, especially for a high contrast scene. For example, if I know that I want a window to not blow out (and to be able to see what’s there), I can’t go over 2-3 stops from 0EV/correct exposure if I want to recover any highlights, so I meter on a highlight, adjust shutter/ISO/f-stop to set it be two stops over, then shoot (assuming my subject isn’t too dark, obviously). On the other end, I know anything below 2-3 stops from EV0 will be crushed.

Referring back to the Zone system, after I determine Zone V (middle gray, 18%), I know that anything below Zone II will be crushed, and highlights above Zone’s VII or VIII will be blown out. So, the best I can tell, I can only get about 6-7 stops of actual dynamic range in an image; certainly not the 14+ stops talked about.

Also, I already know they measure the DR of a camera using a grayscale chart from black to white, with each lighter color representing a stop of exposure. That’s all well and good, but that doesn’t really carry over to the real world… does it?

So, what gives? What am I missing?

Thanks all!

[Adrian Sierkowski]

Nothing. Dynamic range is one thing-- a measure of "oh we still have information here." But they never state whether it's usable. It all comes down, in the end, to your own tastes. How much grain or noise are you willing to live with if you under-expose and bring it up? How much washed out look will you deal with if you're over? technically it's still information. Also you're looking at marketing materials, mostly, of course it's the most flatting.

Latitude, which is what I define as Usable Dynamic Range, is often much truncated -v- what you actually record, and really depends on every element in your imaging chain-- all the way down to what you're looking at something on.

This is why it's so important to do your own tests as close as possible to your actual shooting conditions trying to suss out the look you want.