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HDR

HDR or not HDR, that is the question... Many pro photographers say NO.

HDR - short for "High Dynamic Range" is a blending process that can significantly enhance photos. But many photographers, especially amateur, go way too far in applying dynamic range and end up with a surreal photo - not very lifelike. While I suppose there is some kind of art quality in doing so, I limit my HDR use to enhancing what is already there.

To understand HDR, you must know a bit about Dynamic Range. The definition of Dynamic Range is the range of values from the darkest to the brightest areas. In nature, there are about 11-stops, or Exposure Values (EV) between total darkness and the bright sun. The term EV is identical to stop, so 1 f-stop = 1 EV. The human eye can see about 9 of those EVs.

Other animals, such as Cats have better night vision and can see more EV than humans - perhaps even the total 11 EV spectrum. Film can capture about 7 EV, and the worst of the bunch - Digital sensors can do about 5 EV (although some of the most expensive sensors can reach 7).

 

Now you have to understand that in either film or digital format cameras, you can slide that EV up or down in scale to cover the Dark or Bright areas, but not at the same time. We can use that characteristic to our advantage, and if we take multiple photos, each one exposed a bit differently, we can have a collection of photos that can cover more dynamic range than any one individual photo can.

Special software programs have the ability to blend these photos into one composite, having the advantages of the different values of the individual photos. The end result is a photo with extended dynamic range, or a HDR photo.

To create such a photo, there are several things needed:

  • A camera that can bracket photos, or has the ability to manually change the exposure compensation.
  • A tripod. HDR requires multiple photos, so you will need to have absolutely identical photos.
  • A cable release or IR remote; whatever your camera supports.
  • A HDR software, such as Photoshop or PhotoMatix, which are the two most popular.

Since a tripod and multiple photos are required, the best photos are going to be static scenery. While some photo software has the ability to synchronize minor differences in photos (if you hand-hold the camera), it is a compromise at best. You are far better off in using a tripod. A cable release also prevents introducing camera shake from depressing the shutter.

To create a HDR, you will take three, five, seven, or nine photos. I have found that 3 photos do just fine. When you take the photos, you need to set your camera up to use either exposure bracketing, your exposure compensation setting, or simply shoot in manual mode and change the shutter speed for each photo by 1 EV. For this reason, HDR can only be done in a DSLR or compact having a manual or exposure compensation function.

Whatever method you use, set the first photo to underexpose the scene by -1 EV (-1 stop); take the second photo with normal exposure (0 EV), and take the third photo to overexpose at +1 EV (+1 stop).

You can experiment with +/- 2 EV per photo, or 1/3 EV, taking 5, 7, or 9 photos, and so on.

Once you have your photo set, you then bring them into your post-processing software. The software will normally have many options, so a bit of reading or watching tutorials is recommended to become familiar with the process. Note that you will be presented with several different processing options, some that provide radical results, and some that are hardly noticeable. Just experiment and do what is pleasing to you.

This photo is the "center" photo taken at 0 EV. In other words, it is the "normal" photo; the photo that would be the correct exposure if you were not creating a HDR. But since the HDR image includes the "normal" photo, you can use it to compare the results.

This photo is a HDR taken from a 3 photo set; -1 EV, 0 EV, and +1 EV. While it might not appear to be much different from the first, the sky is a bit deeper, there is a bit more detail in the trees (although at this photo's size, these things may be hard to see). Essentially this is closer to the dynamic range of film, and to me, this is all what HDR is about; to extend the dynamic range while at the same time preserving the image quality. The trees just seem to pop a bit more than in the normal photo.

Note that the water looks a bit less defined, but this is the result of combining multiple photos on a moving object.

The last photo is the surreal nature that HDRs are capable of. The difference between this photo and the HDR above is simply the amount of processing done to the set. I do not like this photo as I think the processing is way overboard. But some do like this kind of photo, and many that think HDR think of surreal photos such as this. While there is certainly more detail in the sky, and you can even see the exhaust from the ship's stack, it looks bizarre. However, I have to admit that some surreal HDRs do look have a poster-like effect, so for specialized use such as advertisement photography, I suppose it has some application.

So in conclusion, don't be afraid to experiment with HDR; and try a few surreal photos if you like. I think though that eventually you will draw the same conclusion in that application of a tiny bit of HDR is better.