I can write this piece for photographers, because I am one, and I am very much a beginner at HDR. That said, I have done enough of this that I feel qualified to offer some pointers. So, here we go.
HDR stands for High Dynamic Range, which means it has a range of exposure beyond what one photograph can reasonably be expected to show you. HDR gives you the highlights of a mackerel sky and the fine details of architecture in the shade. Its really cool, because this is what the human eye can normally see anyway, most of the time.
What’s happening here is essentially, bracketing. You set a single exposure, and adjust shutter speeds around it. If you varied the exposure, then you’d run into depth of field issues, so just lock off the exposure and go up and down with the shutter.
First, get a reading of the right exposure and speed needed to get a very good shot. Then, go into aperture priority, or go manual, take your pick. What is going to happen is you are going to shoot up to two shutter speeds below ideal, and end up at two speeds above it.
The bracketing occurs because you first shoot two below, then one below, then ideal speed, then one over, then two over. That’s the basic idea behind HDR. The varying speeds are going to give you too little light, making the camera drink in all the highlights, and then end up giving you too much light, bringing out the details that hid in the dark.
This is primarily an exercise for digital cameras, but not exclusively so. Since film is inherently a much more high resolution medium than digital can be, this would be an interesting, tho expensive exercise in film. The thing is, once the film is shot, have it transferred to digital as TIFF files, not Jpg’s. Those are the two options I have heard available for transferring film, and, since jpg is a compressed file, you wouldn’t want to go there. A Tiff file shows everything that transferred from the film without the compression math applied to it. A jpg is a shirt folded up for space considerations, and a TIFF is a shirt on a hanger.
From this point on, I will deal with HDR as digital photography. In a digital camera, it is always wise to shoot the picture as a RAW file. Digital cameras usually shoot pictures as jpg’s for space considerations. This type of picture file always has an extra file with a bit of info attached, and the name of that file varies with each camera maker. Nikon calls em NEF files. They have all the details about the file they are attached to. These details go way beyond shutter, aperture, and the usual info you would expect. They will even tell you how many pictures the camera has ever shot up to that point. See, it’s a rather exhaustive list. RAW files don’t have such a file. The space is entirely used by the picture itself, and nothing else. Where a 6 megapixel camera might yield a 2-2.5 megabyte JPG file, the same camera will yield a 15-17 megabyte RAW file. WOW! What a difference! Two things are going on. First, no compression was applied, and second, no NEF file is present, so the picture has all kinds of room to express itself. No wonder a lot of photographers shoot only RAW files.
There comes a small problem with RAW files sometimes. The RAW files need converting so most software can read them. Software conversion programs run a gamut of price ranges, depending on how fine a picture you want to end up with. With HDR, though, the software converts the RAW file in the process of coming up with the final picture. HDR finishes working up the details of the 5 pictures you shoot, and hands you a TIFF file. What’s happening is, its taking the best details of each picture in the range you shoot, and combines them into one picture. It gives you options of what to sort out, such as exposure blending, and so forth. You can fine tune what details the software should look for in the process. But the result is an eye-popper, something so full of detail and richness of color you can hardly believe it!
Now, I use a software that you download free, called Photomatix. The people who have been doing HDR for awhile say its better than PhotoShop for this. That’s quite a statement because PhotoShop has been called the best paint software ever for its purpose. But PhotoMatix has it on HDR. And its free!
One drawback is that until you pay the PhotoMatix maker for the license you’ll have their watermark in three places on your finished work. While its usually pretty simple work just to clone that out, its my usual option to leave it there and practice until I am rich enough to fork up the C note ($100) to get that blasted watermark out of the way.
Now, also with digital cameras, particularly SLR’s there is a way to set up bracketing, and to tell it how wide a range you want to use in the process. Its always good to go out at least two stops either side of ideal, so to get the range of light levels you need to make a really good final product.
There’s my two cents, now go and have fun! HDR is something that you can really enjoy. You WILL definitely want a tripod, and a shutter release device, either IR or cable is also recommended. The software will notice the ever so slight difference in the shot composition, and blend shots, but don’t expect too much from that. ROCK STEADY is what you need here, so the closer the better. No matter how steady you think you can hold a camera, you still shake ever so little, so lock it down as best you can. And the main thing is , ENJOY! Don’t expect perfection, but with practice you will get better.
