Sunday, June 20, 2010

Stay-at-home photos and High Dynamic Range


Try being a tourist in your own home town.  It's a fact that most of us will drive hundreds of miles to a strange location and photograph everything in sight.  Tourists come to Memphis every year in droves and do just that.  The people who live in a given location, however, tend to ignore the familiar world around them.  Admittedly, there are some problems making an image like this, that have little to do with photography, like finding a place to park and walking a couple of blocks in the hot sun.  There are no people in the photo as it was taken on a weekday afternoon when most people are working.  The biggest problem however is a failure to even recognize the possibilities and then making the effort required for it to happen.  Cartier Bresson, the well-known French street photographer once said, "pictures are everywhere, all you have to do is take them".

This is a high-dynamic range photo.  It is composed of three separate exposures taken two f stops apart.  Basically this means one exposure is under exposed (this is to capture highlight detail or bright areas).  A second exposure is made to capture the normal exposure range of the scene (this is the one we always shoot).  And, a third exposure is made that is over exposed (to capture detail in the dark, or shadow, areas).  The three exposures are combined in software.  In this case I used a program called Photomatix, which blends the three after conversion through a process called tone mapping and gives a correct exposure throughout the image.

If you want to try making high dynamic range photos, you should use the aperture control method.  This prevents a shift in focus or variations in depth of field.  Only the shutter speed changes.  Many cameras allow for a rapid fire sequence of multiple exposures.  HDR images can be created with more than three separate exposures—five to seven is common where lighting conditions are extreme.  Three exposure shots like this one can be made hand held if you have enough light and your camera will fire fast enough.  Anything more than three or even three may require a tripod if lighting conditions are such that the over exposed image requires a long enough exposure to cause possible camera movement.  Photomatix is available in trial form from their website as a free 30-day download.  www.hdrsoft.com

The 30-story pyramid pictured here has been a Memphis landmark for many years and was used as a venue for special exhibitions, rock concerts, basketball games and University graduations.  It is currently for sale or lease and negotiations are under way with Bass Pro shops to turn it into a mega-store.  We may be replacing Ramesses the Great with a large-mouth bass.

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