How to interpret D7000 Dynamic Range...

Started Jul 15, 2012 | Discussions thread
summerdream
Junior MemberPosts: 33Gear list
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Re: How to interpret D7000 Dynamic Range...
In reply to Graystar, Feb 1, 2013

Can you provide source for this: a camera meter is calibrated to 12.7% gray and Sekonic meters are 12.5%? I would be interested to read. Thanks.

Graystar wrote:

The dynamic range of a camera is a very misunderstood and misused value.

A camera meter (and handheld meter) is calibrated to 12.7% gray (Sekonic meters are 12.5% gray.) This provides about a smidge less than three stops of highlight space above 12.7% gray. All the remaining stops of DR exist below 12.7% gray. Every camera is like this.

Far more important than the DR is the SNR. For example...a Nikon D7000 has nearly 14 stops of DR, according to DxOMark. A Canon 60D has 11.5 stops of DR. It would seem like the Nikon is far better. But if you compare the SNR between the two, the difference is only 2 dB. One stop worth of noise is 3 dB. Nikon is still better, but not as much as the (misunderstood) DR would lead you to believe. You’re not going to see any difference at the highlight end. The difference will be entirely in the shadow detail. The D7000 will have 2/3 stop less noise in the shadows from the SNR, and a little more shadow detail from the DR.

A typical problem that people have is that pictures of bright outdoor scenes don’t appear as viewed by the eye. To keep highlights such as bright clouds or snow from clipping, the exposure must be reduced...but then everything else comes out looking darker than the scene appeared to the eyes. People blame this on dynamic range, and think that if a camera has a greater dynamic range that image will be more balanced. That is completely wrong. No amount of dynamic range will correct the image.

The problem is caused by the fact that the brain is Photoshopping the scene. Every scene that we see with our eyes is actually a post-processed image that has been manipulated to provide a better view of the world. Consider the following image...

The squares labeled A and B are actually the same shade of gray. The reason they appear to be different is because your brain is increasing the brightness of the area it thinks is in shadow. Your brain is doing this all the time.

So why doesn’t the brain process your picture of an outdoor scene the same way it processed the scene itself? Well, as the CheckerShadow illusion shows, it can...but only if you can fool it. The vast majority of images don’t fool the brain. When the brain views the live scene, it understands that there are large differences in luminance that it must deal with. The extremes in light levels will trigger the processing. When your camera takes a picture of that scene, it represents luminance levels with color. Snow in the sun comes out white, while snow, in the same image, that’s in the shade will be represented as gray. When you view the picture, there are no extremes in luminance to trigger the processing that your brain performs...the eye just sees an evenly illuminated picture, and so represents every color as is.

The bottom line is that scene with extreme differences in luminance will always require post-processing to balance the lighting.

So how does this affect exposure? Basically, when you know you’re dealing with such a scene you must expose to protect the highlights and accept that you need to fix the image on the computer. There simply is no “getting it right” for such scenes.

Personally, I avoid manual exposure because I find it limiting. I find auto modes to be more flexible while allowing control over exposure that is just as precise as using manual mode. I usually use my white-balance reference to set WB and to set exposure. Any time I step into new light, I’ll set a custom white balance. If the lighting is constant then I’ll also press my AE-L button and lock exposure while spot-metering my WB card. I already know that my WB card is about 1.3 stops too bright, so I set my Exposure Compensation to +1.3 and I’m ready to shoot. However, if I suspect that the luminance range of the scene is too large, and my eyes are playing tricks on me, then I’ll have to set exposure by spot meter the brightest highlight in the scene, and then setting Exposure Composure to +2.7. That brings the highlight nearly to white, but maintains detail. The rest of the scene will need to be corrected on the computer.

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 summerdream's gear list:summerdream's gear list
Nikon D7000 Nikon D600 Nikon AF-S Nikkor 24-70mm f/2.8G ED Nikon AF-S Nikkor 70-200mm f/2.8G ED VR II Nikon AF-S Micro-Nikkor 105mm f/2.8G IF-ED VR +1 more
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