Fractal Photography

by Kerry Mitchell

With a little effort and planning, you can use your camera to make quick, colorful and relatively inexpensive prints of your fractals. Photographic prints, when properly done, are more vibrant than inkjet prints and have a much longer archival lifetime than inkjet prints. In this article, I'll describe my technique for photographing the monitor and making fractal photographs.

Image

First, you need an image. When creating your image, you should take full advantage of your system's capabilities. That is, you should create images that use the highest pixel and color resolutions you can display. For example, if you can display 1024 x 768 pixel, true color images, then you might want to generate a 3072 x 2304 image and anti-alias it down to 1024 x 768. You can do this with an image-processing program like Photoshop or Picture Publisher. You may also want to sharpen the image a bit after resizing it. Make sure that your image-processing program has a "view full image" mode, in which the complete image is shown, without any borders or window elements visible (you don't want those in your fractal print). If your image does not have 4:3 proportions, you may want to add black borders around the edges which will help you keep the image centered in the photo view.

Camera

Next, you need a camera. It's best to use a 35mm SLR (single lens reflex, or "through the lens" viewing) that lets you set the aperture and shutter speed manually. You'll need a long lens (focal length of 100mm or longer) or a zoom lens, preferably with a macro setting. This will allow you to fill the viewfinder with the computer monitor. The long lens will also help flatten the image, reducing the effect of the curved screen. You'll need a tripod to steady the camera, and a cable release so you can release the shutter without jarring the camera. Set up the camera a few feet in front of the monitor, taking care to make sure that the camera is square with the monitor face. Otherwise, you'll have some skewing and other distortions in the final print. Use the zoom on the lens, or move the camera to fill the viewfinder with the monitor image. To set the focus, it may be helpful to toggle to a text screen, or to a screen with thin vertical lines. (I find it better to use manual focus rather than autofocus, as some images can confuse the camera.) It's important to use an SLR camera, so you can set the focus with the exact same view that the film will see. "Point and shoot" or "rangefinder" cameras have a slight offset between the viewfinder and the lens. At this close distance, that offset can be critical.

Light

To take the picture, make sure that there's no other light in the room. Cover the windows and turn off any lamps. Any other light in the room will tend to wash out the monitor image and may cause reflections off of the glass. Once you have the image set in the viewfinder, you'll need to set the aperture and the shutter speed to get an accurate exposure. Although it may look like a static picture, you're actually photographing a moving image. Depending on your set up, the monitor is redrawing the picture 50 to 100 times per second. In between refreshes, the phosphors in the monitor begin to fade. If you use a short exposure (less than 1/30 of a second), you'll probably catch the monitor between refreshes. You'll see a dark horizontal band across the picture, where the phosphors are fading and have not yet been refreshed. To compensate for this effect, use a long exposure (1/2 second to 1 second). This will blur together all the dark bands, giving a nice, bright picture.

The other setting that controls the exposure is the aperture. This is the size of the hole through which the light comes. Normally, you use the aperture to control the depth of field of the image, or how much of the image is in focus. However, if your image is completely taken up by the monitor, then just about any aperture setting will have the entire screen in focus. Use the aperture (or f-stop) to control the light: lower numbers (f/4 or f/5.6) to allow a lot of light in, and larger numbers (f/11 or f/16) to reduce the light. Use your camera's meter to determine the appropriate aperture setting.

I have found that strict adherence to the camera's metering leads to overexposing. Therefore, be prepared to take several exposures for each image. You should bracket your exposures, which means taking 2 or 3 pictures of the same image with different aperture settings. For example, if the meter indicated that you should use an aperture setting of f/8 with a shutter speed of 1 second, then you might also want to use settings of f/11, f/16, and maybe f/22. This should ensure that you get at least one exposure that you like. In the long run, it's better to take multiple exposures and only use one, than to go through this entire process and not have any usable pictures.

Film

The film you use is also important. Color film (print or slide) is classified by film speed (ASA or ISO number). The higher the speed, the faster the image will develop on the film. The film accomplishes this by using larger grains, the particles of emulsion that make up the picture. When you have your images enlarged, fast film will give prints that look "grainy". To avoid this, use slower speed film, ASA 100 or slower. This is also necessary to allow you to use the slower shutter speeds needed to avoid the dark bands. For prints, I use Kodak Royal Gold 100 film. Kodak films tend to have a wider exposure latitude, meaning that you can use long exposure times before the film fails to respond as expected. However, I find that this film has trouble accurately reproducing cyans. Recently, I started using Fujicolor Super HQ 100, and like its colors better. The best way to compare films is to shoot the same series of images with each film, have them developed and printed at the same lab, and compare the prints.

Printing

Once you've shot your roll, you have to entrust it to a photo lab for developing and printing. Unfortunately, this step is critical to getting good prints, and is one over which you have little control. The developing of the film is automated and usually goes well. The printing step is usually done by someone who may have a pretty good idea of what people and landscapes should look like, but may have no idea how fractals should look. This is important because the printer has a lot of power in determining the final color of the print. Further complicating matters is that you can never exactly match a print to what you see on the screen. The screen image represents transmitted light, which is of a different quality than the reflected light coming off of the print. If you decide to take a lot of pictures of your monitor, it will be important to find a photo lab with whom you can work and who will take direction. I use one-hour labs, because I can give immediate feedback to the printer about the colors. The printer will generally have control over either the red, green, and blue channels, or the cyan, magenta, and yellow channels. Also, they usually have a "density" control; low density makes the image too bright and washed out, while high density makes the colors very vibrant and dark. If possible, you should have a color guide to show the printer how the colors should look. If you have a good color printer, you can print one or two images and give them to the printer to match. Or, you can create a "test pattern" of standard colors. Have the printer correct for the test pattern, and then print all of the other images the same way. When you get a good print of your image, use that as a color guide when you have enlargements made.

While a bit involved, this technique provides a means of creating photographic prints of your fractals. When you master it, you can create small- to mid-size enlargements quickly, easily, and with minimal expense. Have fun with it — I have.

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