What is HDR

 

HDR Tools

 

How do you start?

 

How many images?

 

What is HDR

I am rather new to HDR having been introduced to the discipline by a Chris Alvanas in April of 2009 through a class in Georgetown, Washington D.C.  This experience has really affected my photography and how I see images.  Many thanks to you Chris for a wonderful class ( http://www.lightyearimaging.com ).  Also, because a lot of images of buildings lend themselves to HDR images, E. David Luria (http://www.washingtonphotosafari.com/learn.htm ) introduced me to his tips in basic architectural photography which have enhanced my HDR photos.

For those not understanding HDR photography, my take on this discipline is the ability to expand the photographic image to an extent that approximates what the human eye can discern. When one takes a single photographic image with a camera, there is only a small exposure range that can be displayed.  If the light through out the image has the same intensity, the entire image can be properly displayed on the screen or in print without significant post processing. All elements of the composition will be presented in the same light without significant light or dark areas. In addition to the warm light presented by sunrise and sunset, this is the primary reason, in my opinion, that photographers try to take their photos during this “golden hour”.  In this relatively low light situation, the sun’s light is diffused over the entire area leaving the image pleasantly exposed.  

Most of the daylight hours (unless diffused by clouds), are typified by high contrast associated with areas in bright sun light and dark shadows which result in part of the image being properly exposed and other areas being blown out (all white without detail) or very dark (again lacking detail).  HDR photography addresses the limitation of our cameras by having the photographer bracket (multiple exposures at different shutter speeds with the same aperture on a tripod) their exposures from under exposed to over exposed for a given situation.  The generally overexposed images will capture the detail in the dark areas while the underexposed images will capture the detail in the bright areas of the image.  Using software (I use Protomatix Pro3), the image details are combined from all the exposures into a single file that you can then manipulate to more fully represent the actual scene.  The typical example is taking a photo within a room with a window.  Normally, the window scene will be displayed with a lack of detail in the room or the contents of the room will be displayed with the window being a hot spot of white. This process permits the photographer to capture the detail outside a window while permitting the room detail to be visible as well. In scenic photography, this discipline permits the photographer to capture the blueness of the sky while preserving the detail in the bright sunlight and dark shadows.  In my photograph of the carousel on the Washington Mall, I am able to have the shadow detail of the underside of the roof, the animals while still having the detail of the clouds.

Another advantage of HDR photography is that you can achieve vibrant images outside of the “golden hour” discussed earlier. Instead of being in position before dawn, most images can be taken at any time of day and still have a pleasing composition of exposure. One exception to the morning “golden hour” photo shoot is when you want to have the lighting provided by structures in the images be present in your photo.  Specifically, while my pool photographs at the Marriott Grand Vista during the day are nice, they miss the color available when augmented by the artificial light above and below the pool water when shot in the fifteen minutes before and after sunrise.

HDR Tools

My current HDR tools are Protomatix Pro3, Lightroom 2.5 and Photoshop CS4.  Unfortunately I have not mastered the Photoshop image layering and my images at this point have not taken full advantage that software’s capabilities.  That deficiency in my photos should be addressed by my taking the class (advanced Photoshop) I have scheduled in late January. 

How Do you Start?

As David said many times in his Photo Safari classes assure that your camera is level.  If it is not, the lines on your images of buildings will be converging as your eye goes up the image.  As Chris stated in his HDR class, do not be afraid of using the software image sliders.  Move them significantly to see the impact of the slider (different sliders change color, temperature, exposure etc.).  You can then move them back and forth in smaller increments to make fine adjustments.

How many images should I take in my bracketing? 

This depends upon the variance in light associated with the image you are trying to capture.  I have taken anywhere from three to seven exposures with one image at nine exposures. The greater the variance of the light in the image the more images you might want to take. 

What about people in a bracketed image? 

Protomatix Pro3 does have the ability to reduce ghosting of moving objects such as people, cars etc that seems to work; however, sometimes the blurring of moving objects adds to the composition of the image.