Hello Friends and Family,

Link to this year's index by clicking here.

Desert Botanical Garden: Chihuly, Part 5

Obviously, I was extremely impressed by the Chihuly exhibit during the day. However, when the sun when down, the real magic started. Enjoy.

Photographic Nerd Alert: For those not interested in the technical aspects of nighttime photography simply skip over this week's text and enjoy the photos.

As most photographers know, the human eye is far more sensitive than film or digital sensors. Therefore, low-light photography usually entails a compromise. If you expose your shot for the lightest area, the shadows become black. If you expose for the shadows, the light areas get burned out. To help with this problem, a new advance was introduced in Photoshop CS3 — High Dynamic Range or HDR.

In order to use HDR, the photographer must take multiple exposures of the same scene with different exposure settings — also called "bracketing". Most of these shots were taken using what I thought would be the best exposure then one stop lighter and one stop darker. The other factor is that each of the three images must be framed exactly the same — meaning that you must use a tripod, being careful not to move the camera or tripod between shots. One last point is that in changing the exposure, you must use different shutter speeds, not different apertures — so that the depth of field differences would not give you varying fuzzy edges around objects that are not exactly in the focal plane.

Once you capture your multiple images you must use software to analyze those images and construct a new image using 32 bits (instead of the usual 16 bits found in RAW images) with a wider latitude of exposure. Photoshop does this — but in my opinion (and that of other photographers), it does not do it particularly well. Therefore I used a package called Photomatrix that does a better job although its user interface leaves much to be desired.

This HDR image can then be manipulated in Photoshop in the same way that any other image is manipulated. You adjust the brightness, contrast and saturation until you are happy with the results. The final steps are cropping and sharpening. And voilà, you have beautiful night photos.

This experience has only whet my appetite to do more with this technology. Note that this is not just for night shots, but can be useful indoors, for example where a window provides bright light. As above, if you expose for the exterior view, the shadows will be black. If you expose for the shadows the window will be all white. A compromise exposure will lose some of both highlights and shadows. HDR provides a method to capture it all.

Unfortunately, there is one limitation that makes HDR less useful for my photographic passion (Hawai`i, in case you haven't noticed) — that is cases where objects are moving as you try to get the three exposures. Objects like waves, swaying palm trees or flying birds just won't stand still for those three shots. Oh well — at least I have one more weapon in my photographic bag of tricks — just waiting for opportunities to use it.

The tour concludes next week with more nighttime images...

Life is good.

B. David

P. S., All photos and text © B. David Cathell Photography, Inc.