Hi,
I have made a few experiments with HDR in the past year. The experience has mostly been mixed, but more negative than positive.
Erik,
All the more reason to have a camera with a high DR, to reduce the number of occasions when you might see a need to bracket exposures in order to merge to HDR.
Being aware of a need to bracket exposures in order to increase DR is one thing. Being able to do that successfully is another thing. First, the scene really does have to be stationary. I've bracketed exposures of the Himalayas with camera on tripod, only to discover back home that the very slight breeze causing movement of the tall grass in the foreground, and the slight movement of the distant clouds in the background, has made the merging to HDR process too difficult to bother with.
In such circumstances I choose the exposure which is closest to an ETTR and do my best to cover up any noise which might be apparent in the shadows.
Having successfully merged different exposures to HDR without any 'misalignment' of detail, there's sometimes a further problem of making the right 'tone-mapping' adjustments to get the image looking natural.
In my view, this is partly because one is faced with a whole new system of tonal adjustments which are different from the regular adjustments in ACR that one might be familiar with.
Another issue is the number of auto-bracked shots the camera is capable of. I've often found with Canon cameras that the maximum of +/- 2EV with just 3 shots is not ideal for merging to HDR. The extension of 4 stops of DR may be sufficient, but the gap of 2EV between each exposure may not produce in the best result. 5 frames with a 1EV difference between shots would be better.
So, what I try to do is to expand dynamic range. Problem is that we still have a limited dynamic range for display, something like 1:500 on screen and 1:120 in print. What I have found that the real world density range on my cameras (Sony Alpha) is good enough that I can extract shadow detail from an -2EV exposure.
I've noticed, Erik, that you've mentioned this factor before, quite frequently, implying that in some way the DR limitations of the print medium makes a high DR capability in the camera irrelevant or less relevant.
This is simply not true if one knows how to process an image in Photoshop. It's possible to display, in a natural way, the full dynamic range on the print of any correctly exposed high-SBR scene, even if the scene encompasses a whopping 20 stops of DR.
How is this possible? First, let me explain how the eye perceives a scene. (In simple terms so I can understand it myself).
The eye has a surprisingly narrow field of view as regards discernment of detail. Peripheral vision tends to give us the impression that the eye's FoV is quite wide, but peripheral vision is mainly good for the detection of movement. It's totally hopeless for the discernment of detail. To see all the detail in a scene that may be captured even by a moderately wide-angle lens, we have to shift our gaze from side to side, the equivalent of image stitching in a camera.
A similar situation applies to the eye's DR capability. When perusing a scene, we find in one moment we can see lots of detail in the white, fluffy clouds in the sky, then a fraction of a second later, as we shift our gaze to some shadows at the foot of a nearby tree, we can see leaf litter and lots of fine detail in the dark shade which really doesn't look all that dark anyway, but
would look very dark if we were to photograph the scene with a single shot, exposing for the clouds.
It's easy to get the impression that the eye has a very wide DR capability. In a sense, it does, but only because it has the capability of bracketing exposures. The pupil of the eye, which is similar to the aperture of a camera lens, can dilate and contract in a fraction of a second in order to accommodate changing brightness levels.
Sometimes, when the change in brightness is extreme, it may take several seconds for the eye to adjust, such as coming out of a darkened cinema into the bright sunlight. But normally, a shift in brightness of just a few stops is almost instantly accommodated by a change in the aperture of the pupil.
So basically, if we compare the eye with a camera, using camera terminology, the eye is continually performing image stitching to widen its FoV, and continually bracketing exposures in order to increase its dynamic range.
A single shot from a camera,
any camera, even the D7000, cannot compete with the eye as it's normally used with its continual gaze-shifting and changes of aperture.
Okay! All that must be crystal clear to you all, so let's move on to the print. How do we portray on a print, with its very limited DR, the full DR of a 20 EV scene?
Well, I'm no expert on the potential of the myriad of processes and techniques in Photoshop. I'm sure Jeff Schewe could make me look like a complete novice in that respect.
But there are a few very simple techniques that work quite well for me. First, the Shadows/Highlight tool. You need to be in advanced mode of course, but this is a tremendously useful feature in Photoshop for quick adjustments of balance between shadows and highlights. If you need more extreme adjustments, you can repeat the process.
Another simple technique (you must have noticed, I like simplicity), is to select with the lasso tool any area on the image you want to treat separately, feather appropriately (30, 50 or 100 pixels), then apply whatever adjustments you think appropriate.
By such processes, you can achieve on the print, the full detail of a bright cloud in the sky, and the full detail in the shadows at the foot of a tree in the foreground,
if your camera has sufficient DR or,
if you bracket exposures and merged to HDR.
Messing with HDR doesn't really make the image better, even if I get less noise and better resolution in the shadows. On the other hand it's easy to get unrealistic color with HDR
.
You are confusing the 'subjective' with the 'objective' here. The term, 'better', without a qualifying description, is about as subjective as one can possibly get. However, 'less noise' is a comparative matter which is either true or false. If it is determined to be true, objectively, through the sorts of measurements that DXO make, but subjectively one cannot see it, then one can reasonably surmise a number of possible causes.
(1) One doesn't know what 'visual' noise is and therefore cannot recognise it.
(2) The differences in noise are so small that they are irrelevant in practice, or beyond the threshold of normal discernment.
(3) The display medium, monitor or print, is not of sufficient quality, or not sufficiently well-calibrated, to enable the observation of such differences.
(4) The observer has a medical or genetic problem with his eyesight.
Of course, there may be other reasons of a more psychological nature, which perhaps we should not dwell upon. People can have 'blind spots'. Sometimes seeing the truth is too painful, so we bury our head in the sand.
Sometimes people identify so strongly with their camera equipment that it becomes part of their personality, so any criticism of their camera equipment is viewed as a criticism of themselves, their taste and their judgement.
So, if camera A has better high-ISO performance than camera B, then someone who owns camera B, of which he is very proud and which symbolizes his good taste and discernment, may first try to dispute the validity of the tests that imply that camera A has better ISO performance.
Having failed to convincingly win the argument that the tests are invalid or inaccurate, because of mounting photographic evidence that camera A really does have better high-ISO performance than camera B, the owner of camera B may then resort to other tactics to preserve his self-esteem.
A typical response might be, "I never use high ISO, so it's irrelevant." Or, in the case of camera A having a wider DR than camera B, "I'm not interested in pixel-peeping shadows. The DR of my current camera B is quite sufficient."
One sees many examples of such attitudes on DPreview.
By the way, Erik, your example images of HDR do not appear in IE when I click on them. There's something wrong.
Cheers!
