Wednesday, July 1, 2009

There's an old saying that if something seems too good to be true it probably is too good to be true. I know of one thing that's lived up to this type of hype, but that was in a far different part of life. Our image today has tremendous Depth of Field. Depth of Field is defined as the area of acceptable sharpness. In any given image there is only one truly sharp plane of focus, but due to the gradual drop off there is an area that appears sharp. The length of that area is determined by the aperture selected. If you'd want to get far down into the minutiae of optics it's the area where the "circles of confusion" are small enough so as not to affect the clarity of the image. Fortunately this blog isn't an optics blog and won't get into a discussion along those lines. Suffice to say, sooner or later, things get fuzzy. Can today's image really have as much Depth of Field as shown?

Sure it can, the only problem is you can't have this shot with that much DoF. With a extreme wide angle lens you can have acceptable sharpness from a few inches to infinity. We don't have infinity here, but we do have a couple hundred yards to deal with. If this shot were taken with an extreme wide angle lens and the carved tree and pen knife were in focus, the bridge would be a very small piece of the image. In order to have both the tree and the bridge as objects central to the story being told the final image was made by compositing two shots. Just as a disclaimer, no trees were harmed in the shooting of this image. The "tree" was a piece of fire wood from a tree cut down by the town's highway crew after a major storm. I got some jaundiced looks from the foreman when I asked for one piece of wood. Even more when I spent twenty minutes picking through the pile to find just the right piece.The major (background) portion of the image had been shot months before and needed "something" to make it work. The fence and tree in the foreground gave some depth, but something with impact was needed to finish the story. I spent about two night carving the heart and initials in the wood. (The little pen knife wasn't really used to do the carving, but I thought an Exacto knife would have ruined the mood.) The third night I shot it. Two speedlights were used to get the highlight and shadow detail just about right without having too obvious of conflicting shadows. The second shadow is there but, unless I mentioned it, you probably would have let it slide. The rest was just a case of, basically, doing a cut and paste of the "tree" into the covered bridge image. It is possible to get some great Depth of Field, just not as much as would have been needed in this image with the lens needed to get the bridge the right sized. When shooting, make the decisions about what you're trying to accomplish. Control the important factor, weather it's short DoF, long DoF, stopping action or accentuating motion. Once you've "seen" the final image in your mind let the camera do the mathematics. That's one of the things you paid for. While it's important for you to know the what and why the camera is going to do something, The camera is much more accurate in figuring out the how once the important decisions are made.