HDR Workshop May 25, 2010


Workshops

The High Dynamic Range workshop was conducted on May 25th, from 6:00pm to 8:00pm at the Senior Center. The group was over 40 members and guests who were asked to bring their camera and we as a group went outside to take some photographs to be processed in the workshop. After a few images, we came back in and downloaded the images then began using Photomatrix to process our images. Ted went over each control of the software and gave some guidelines on the constraints on the values of the controls. Too much on one control can make an image look surreal or too little can leave a image flat and lifeless.

Below is some of the notes from the evening.

The Purpose of HDR Photography is to collect as much detail as possible from a very contrasty scene that could not be fully recorded onto one piece of film or even in one very high-quality digital capture, but that the human eye can perceive. It goes without saying that maximum possible quality is the objective, so shoot RAW. An HDR file can be processed directly from RAW files but Photomatix does not gather these files inclusive of any adjustments you may have made in Adobe Camera RAW; if you want to include tonal adjustments or even local adjustments, the RAW originals must be processed into jpegs or tiffs or Photoshop files first, and then sent to Photomatix. HDR photography works best for scenes with no moving objects. Two exceptions come to mind: windblown clouds and moving water provide surreal results you might like. Moving objects like wind-blown bushes and trees will lead to multi-imaging that usually does not look good.. Photomatix has some ability to resolve the ghosting that occurs, but this is mainly for objects moving across the frame, such as a person walking or a bird in the sky.

Equipment Needed: Tripod, digital camera with auto-bracketing capabilities, cable release, (no touching!) and the biggest lens shade you can get your hands on (..a big piece of black cardboard will do). If you have an older DSLR without auto-bracketing, you will be forced to handle the camera, so take your time and be careful. Photomatix has some ability to make sense of the variations in your image set if you happen to move the camera while making adjustments.

Aperture Priority: Be sure to shoot in Aperture Priority mode so that all of the exposures are optically the same and set the auto bracketing for one-stop variations. Shooting in manual mode forces you to handle the camera to make exposure adjustments and shooting in shutter-priority mode or program mode will deliver a set of images taken at various aperture settings with varied depth of field that may cause problems later.

Mirror-Up: If your camera has a mirror-up shooting mode, use it. Even at fairly high shutter speeds, the shooting process causes cumulative vibrations that are sure to lead to soft images. Mirror-up shooting requires pressing the shutter release twice for each frame – once to raise the mirror and once for the exposure itself. Shooting at very long shutter speeds (5 seconds or more) probably makes this unnecessary since the unwanted vibrations are happening during a very small percentage of the exposure time.

Prime Lenses: Try to shoot with prime lenses, also referred to as fixed focal length lenses or, simply, fixed. A zoom lens could self-adjust its focal length during the exposures due to vibrations, changing image sizes throughout the set. Using the lens in manual focus mode might be a good idea for the same reason. And generally, zooms lenses tend to be inferior to primes. High-priced zooms are very good, but still not as good as primes.

More is Better: Sometimes three frames are enough, but more are usually better. I have done as many as 9 frames and sometimes throw out one or two at either end of the bracket if the tonal range of a particular scene is not extreme, but sometimes using more frames than necessary leads to very smooth tonal gradations and looks beautiful in softer scenes, too. But for a scene with extreme brightness range, use as many frames as possible. Remember, the main purpose of this process is to collect as much detail as possible. Too much detail is a good thing in this case and you can use less than all of it if you want to. If your computer has plenty of horsepower, let it work. More frames are better.

HDR From a Single RAW File: It is possible to use HDR technology for a single RAW file and that is simply to duplicate a RAW original as many times as you think is necessary. I usually duplicate it twice, for a set of three. You can then send these (3) files to Photomatix, which recognizes that they are not from a true bracket made in the camera. You will be asked what exposure range you would like applied and Photomatix processes the files as though they had all been shot separately in the camera. This works well for pictures with moving objects such as people, but be careful: it does not usually produce pleasing results for portraits when smooth skin tones are needed as it tends to be very harsh. And, if you have older images that seem to be missing something, this simple process can bring a lot of life to them.

 

Ted Dayton’s HDR Compromise

HDR technology is very powerful, and sometimes so powerful that results can be silly-looking. As with most amazing new tech tools, they tend to be overused at first because it’s fun to see such new-looking imagery, and I was guilty of that. But rather than using HDR to make images with a big WOW factor, I have found ways to use HDR as a tool for achieving truly realistic results that also have a contemporary and personalized look to them, and this is what I do:

I create a fairly dramatic-looking HDR image using the steps I described earlier and process it as a tiff file and save it. I then return to one of the RAW files near the center of the bracket set and process it for maximum detail. This image is usually a little flat and dull, just what I need. I also save this file as a tiff file and then open my two new files in Photoshop.

I start with that flat image made from the single RAW file and layer it onto that over-the-top HDR image I made in Photomatix. I then select that HDR file and see in my layers palette that there are indeed two layers now, the upper one being the flatter, more conventional-looking image, the lower one being the HDR. I can then blend these two images by moving the opacity slider for this upper layer until I like what I see. I have found that 50%-75% of the upper image (25%-50% of the lower image) is a very nice blending. Depending on the image, I can make this simple process work very well for nearly any image and it adds about 5 minutes to the entire process. If the image is important to you and you want the power of the HDR process without the sometimes-comical look of it, this will be well worth the extra effort.

If you have known me for a while or taken my classes, you have heard me implore you to find ways to put your personal stylistic stamp on your work, even if in a subtle way. This process insures that it will turn out your way because there are enough steps and variables to make it virtually impossible that someone else could produce the very same result from the very same original photograph.

 

Article by Douglas Wade
Photos by Lee Garner

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