Seeing like an eye, HDR coming to cameras soon
Welcome aboard photo enthusiasts. Last time I threw out the acronym HDR, which stands for high dynamic range. Possibly some of you have been to a Peter Lik Gallery and viewed his beautiful landscapes that in part benefitted from the HDR effect. This is a most significant development that will make everyone look like a professional when seeing the results of their travel shots. Well, not exactly, but it will make photographs in general look a lot better.
Actually making an HDR photograph has been remotely possible for a long time, but with today’s technology it now becomes far easier and greatly improved. By now I’m sure you would first like to know what this is… what it means.
With film and now digital it has (thus far) never been possible for a camera to see better than the human eye. The measurement of latitude of what you are able to see from the brightest to the darkest areas (or by sa versa) can be given by a range of f/stops.
Transparency (or slide) film had the least tolerance. Negative film is able to encompass a range of possibly four to five f/stops and digital is able to do slightly better. An example may help explain all this. Likely we’ve all photographed a sunset. What we get is a beautiful sky, and the rest is a dark un-seeable silhouette, (and from my point of view not very exiting picture). Our eyes can see a lot more detail in those dark and shadowy areas, because the range of our eyes can be eleven to fifteen stops of light.
The reverse is also true. In taking something mostly dark, or exposing for the shadows a camera will loose all detail in the highlight areas. Those will be “washed out.” Here again our eyes will be far superior in giving us a full range of details.
The solution for making better photographs, that is, one’s that have a greater range of visibility (and color vibrancy) like that approximating the capability of human vision, is to take several photographs of the exact same scene with a camera using different exposures. The photographic term is “bracketing.”
This means we expose to capture the highlights, expose for the shadows and blend it with a normal (or optimum) exposure, and in this way we increase the overall dynamic range to produce a photograph that simulates what the eye can see.
The obstacle with film is sandwiching the three (or preferably a few more) exposures in the darkroom to make a final print. Obstacles of proper registration and density of multiple layers of film make it nearly impossible.
Digital makes it easily possible. You can take several, more than three if you like, exposures to capture all the highlight, shadow, and normal detail of the exact same scene, bring them into your computer, and using software sandwich them precisely and blend the best of each for a result of making a fully eye pleasing image.
Now you are capable of making an HDR photographic image. But if you consider the process thus far you will recognize there are still a few problems to always having a successful outcome.
The first is framing each photograph exactly the same to duplicate (referring to getting proper registration) every exposure. This is easily accomplished by adjusting the shutter speed (not the aperture that will change the depth of field) and using a tripod… Well, this method would be fool proof and easy if you’re not on a rolling yacht or taking fast moving objects. So as you can see the process can still be very complicated.
We are now saved by technical-scientific advances. Supposing we make cameras that take several photographs at the same instance at varied exposures. This would eliminate the tripod or concerns about moving subjects. For that matter it eliminates the need for the computer and software to handle this specific process.
We do not have to suppose anymore. This in-camera HDR is coming into play now, and before long, as with all technology, especially those advances not prohibitively expensive, this will soon be standard issue for all cameras.
It will not decide for you what will make a truly great shot or improve your composition in taking it, but it will make whatever you take look better. We are all going to want HDR when it fully reaches our shores. During the wait I’ll take permission to come ashore.