Why people mistake DR for exposure latitude?
I always thought they were the same. Care to explain the difference?
Dynamic range refers to the total maximum physical range of tonal levels a camera sensor is capable of recording. Exposure latitude refers to the ability of an actual exposure taken with a camera to be tuned or adjusted. A true RAW photo strait off the sensor is very dull, flat, lifeless, lacking a significant amount of contrast. When we import our RAW photos, most RAW editors apply a tone curve. Usually one of the manufacturer defaults (such as Camera Standard or Camera Neutral, etc.) These tone curves adjust how levels are allocated in the final image you see on your screen.
In a linear image, levels are distributed equally (hence the dull, lifeless, low-contrast appearance). With a tone curve applied, more levels are allocated to the shadows and the highlights, effectively "compressing" the wide dynamic range into a narrower contrast range. That brightens and adds life and color to an otherwise dull original exposure. The side effect of that is you have a lot of levels "bunched up" in the shadows and in the highlights around the roughly linear growth of the midtones. It's thanks to these tone curves that we have the ability to "recover" highlights and "lift" shadows.
Technically speaking, LetTheRightLensIn is correct...there is no such thing as highlight recovery or for that matter shadow lifting. Not with a true RAW image that has not yet had tone curves applied. But we generally don't work with our RAW photos in their true form. When it comes to the shape of tone curves, Nikon tends to allocate a lot more levels to the "foot of shadows" than Canon (and, for that matter, most other manufacturers, including MFD manufacturers.) They have more freedom to for sure, thanks to their lower read noise. That doesn't account for the ability to push shadows around by as much as 6 stops though...Exmor sensors only offer about 2 stops of additional DR in the shadows. Examining Nikon's tone curves indicates they allocate more levels to the shadows than their low read noise offers alone with their curves.
Similarly, Canon allocates more levels to the "shoulder of highlights" in their tone curves. They don't allocate as many more levels to highlights as Nikon seems to do to the shadows, however in Canon's newer cameras their highlight shoulder tends to be a little longer and fall off more into the highlight range than Nikon cameras. This is part of the reason you can overexpose by four stops with a modern Canon camera and still be able to recover (although its doubtful you could overexpose by 6 stops and still recover...Nikon still has around a 2-stop DR edge in the end.)
Exposure latitude is benefited by these tone curves, and the ability to recover highlights and shadows from "beyond the foot and shoulder." Exposure latitude is enabled by DR, and the more DR you have, the more you can tune those curves to allow greater and greater latitude.
Even if they do suggest to the RAW programs to place things differently and use a different default tone curve. The thing is with RAW all you do is pull a few sliders and everything is totally different than the default anyway.
D800 sensor has 2.6 stops more DR regardless (and the actual usable difference is over 3 since it has so much less banding junk, so real world actually makes it even greater than the most simple lab measurement).
Anwyay I'm kind of tired about the DR talk. If Canon doesn't get the message by now, they never will. Hopefully that new CR rumor is true and they have gotten the message and hopefully they will carry it off in a way that is as practical and universal as Sony has.
In comparison to my 7D, the D800 is 2.3 stops better. Period. I don't downscale my photos...on the contrary, I tend to upscale them, so there is no benefit of any kind of the D800 above and beyond the hardware's native 2.3 stops. In comparison to the 1D IV, the difference is only 1.7 stops.
As for the banding argument, baloney. There are PLENTY of samples from both the D800 and D7000 that show horizontal banding. Exmor's CP-ADC eliminates vertical banding, but you still experience horizontal banding...and oddly enough, it actually seems to get worse as you increase ISO, whereas on Canon cameras banding reduces and disappears as you increase ISO. There is no magic bullet here that makes REAL-WORLD performance of the D800 some 4.4 stops better than a comparable Canon camera. That is the kind of baloney that will sink organizations like DXO that use shady comparison techniques in the long run.
When it comes to comparisons, of hardware-dependent capabilities like DR, I could give a flying rats ass what two cameras look like when their post-conversion images are scaled down to the same tiny size. What I really care about is what the hardware is actually capable of. In that respect, I have no problem applauding Nikon and Sony for the approximately 2 additional stops of DR and amazing shadow recovery abilities. But I greatly dislike how so many people, thanks to DXO, now honestly think the D800 is capable of 14.4 stops of DR in native output (unscaled, dropped strait into <editorofchoice>, ready for processing.) Its flat out incorrect, inaccurate, and is greatly misleading to potential buyers...many of whom certainly seem so roped in by DXO's "score" that they've literally dumped their Canon kits and jumped brands (at what has to be considerable cost...to some who had extensive kits with expensive lenses, a cost of thousands).
If Nikon actually had a 6-stop benefit over Canon, I'd jump ship in a heartbeat, but that isn't the case. Canon can (and probably will) do better in the future, but as things stand now, Canon cameras are far from the horrid worthless POS's they are increasingly made out to be...and I simply wanted to demonstrate that.
