by John VanSteenberg
How HDR processing saved the day …. and the landscape.
Lots of people take lots of ‘landscape’ images, particularly on vacation. This is a little different situation. Recently, I was asked by a friend to photograph a residential landscaping project his company had done. He wanted to give the homeowner a gift of images of the grounds and the stonework and the lighting that the firm had done.
The weather was projected to be perfect: sunny and clear. Based on our schedules, we had a brief window to do the shoot. So, the time of day was fixed according to that as mid morning.
When I got to the location, the home and grounds were beautiful. There was just one problem: contrast. Hard sunlight creates deep, dark shadows (lacking details), harsh highlights (with no detail) and almost no mid-tones. In reviewing the location of the important elements for some of the images, some were deep in shadow surrounded by overly bright scenes (for example: the stone wheel was in deep shadow, the lawn behind it vastly overexposed). So, I was forced to make some choices. I would have to expose the image to either emphasize the shadow areas (the stone wheel), or the highlight areas (the lawns), or, if an averaged exposure, the scene would be very ‘contrasty’ with blocked up shadows and highlights, with loss of the transitional mid-tones in both the wheel and the lawn. So, while I could get a ‘correct’ exposure, under the conditions, I would have to sacrifice some aspect of the color, detail, or tonal range, and the client would not get a very pleasing image. Not what I had in mind.
Therefore, I decided to use an HDR technique to combine tones from a variety of images, made at different exposures, to optimize the detail, color and dynamic range, and to make a stronger image. Using HDR, I had the ability to record about 12 EVs of total scene brightness range, instead of the approximately 8 EVs the sensor normally records. This would allow me to produce a full range of tones and image detail in each, the shadows, the mid-tones and the highlights. I could also control the lighting to adjust the level of drama I wanted to convey.
Most people think of HDR as a technique to make “impressionistic” highly stylized images. Many don’t realize that it can also be used to extend the total dynamic range, capturing more data and smoothing out contrast issues and adding both highlight details and shadow details, all done by combining multiple exposures.
In this case, the impressionistic style was not appropriate for the purpose. But, once I did what the client needed, I did play around with the typical ‘special effect’ impressionistic renderings. That was more for my own fun, not the real client work. I will post about that separately. But for the client, the real thing is the difference between a good conventional exposure and an HDR image made from 5 RAW files.
I could have used 5 jpegs, but I wanted all of the RAW tonal data available to have the greatest opportunity to control the outcome. So, I shot the images in RAW format.
Above: these are the camera-rendered jpegs of the various exposures to show how the various exposures still lack full tonal information.
For the final image, I also made a minor horizontal leveling adjustment to eliminate the out-of-level roof slop and create a strong horizontal format image.)
Another viewpoint: these images are the back patio view of the stonework and transition pathways into the wooded areas of the property. Even in deep shade, the tone mapping power of HDR brings out much more detail.
I made the images with either my trusty SP 17-50/2.8 or my SP 10-24 wide-angle zoom lens. I combined the 5 images in each scene using a $40 program called “ Photomatix HDR Essentials” from HDR Soft. They make a ‘Pro’ version for over twice the price. I may upgrade, if I find a reason to do so. But I am very happy with what the $40 version does. The interface on the stand-alone version is very simple and easy to manipulate. (They also make a Lightroom plug in version.)
The keys to HDR: the procedure is to take several captures, varying exposure in each.
1. Make several (2 to 5 or even more) exposures of the exact same field of view.
One correctly exposed. (plus) One or more progressively over exposed and one or more progressively underexposed (usually by one to two stop increments in each capture’s exposure). (A ‘typical’ sequence would be: -2, -1, 0, +1, +2 EVs.)
2. Using HDR Soft’s extremely easy to use program interface, drag and drop the images you want to use into a window. The software displays a proposed image and several optional presets. If you want something different, you can play with adjustments to change the outcome over a wider range of possibilities.
3. Some hints and things to watch out for during capture. In the case of these images, I used 5 images combined to create the final results.
a. Make sure that you stabilize the camera on a tripod.
b. Pre-focus being careful about the depth of field (to emphasize both the key foreground and distant objects, or to select the key elements to be emphasized/de-emphasized in the final image).
c. Do not change either the focus point or the aperture from one capture to the next, of each scene.
d. To change the exposure to make the series of captures, you can:
i. change your exposure by setting the camera on ‘manual’ exposure mode and changing the shutter speed (note the under/over exposure in the meter display). (or)
ii. while in aperture priority mode, by using the exposure compensation feature (note the under/over exposure in the meter display).
e. Be very careful to watch for movement in the subject (tree branches and leaves, flowers, a pet wandering into the scene, etc.) While the changes in the scene might seem small in the viewfinder, they get quite pronounced in the enlarged image and can either be very mysterious and pleasing or destroy an otherwise great image.
