Duplicating Slides

If you send your slides to clients or like to enter contests, It is better to make duplicates to prevent damage to your originals or possibly loosing them. By duplicating your slides, you can also correct some exposure problems, color, or cropping. Slide duplicating is not as difficult as you might think. If you only need a few duplicates made, you can have them done by a lab. However, for large numbers of duplications, you save a lot of money if you do your own, and have more control over the results. Duplication increases contrast and there is a loss of sharpness, so don't expect your duplicates to exactly match your originals.

There are several ways you can duplicate your slides. Slide copiers are one way to get professional duplicates. These units have built-in electronic flash, diffuser, and filters. You place your slides on the light box to copy. You also need an extension device, either bellows or tubes or a macro lens that can focus to life-size. To reduce contrast, a second flash built into the duplicator can be fired to slightly fog the film. Low contrast originals won't need flashing, but high contrast images will be produced too contrasty unless you fog the film to some degree. Slide duplicators are the most expensive method of getting duplicates. If you are going to do a small numbers of duplicates, you can get a slide-duplicating attachment. These are tube like devices that attach to the camera like a lens. They include a close-up lens, slide holder, and a diffuser for even illumination. Some models feature zooming for up to 2.5X life-size. You simply point the duplicator at a light source and shoot. The major problem with these devices is the quality of the close-up lens. The major advantages is their low cost. You can purchase one of these duplicators for under $100.


Slide-duplicating attachment

You can also use a macro lens or a 50mm lens with extension tubes or bellows and a tripod or a copy stand. Back light the slide and make sure to mask off the surrounding. The forth method is by projecting the slide onto a matt white surface, and photographing the screen. To avoid distortion, get as close to the projector as possible. You can also use a light box to make duplicates with a macro lens or a lens with extension. This method uses very long exposure times resulting a shift in color. You can correct this by placing CC filters over the lens.

An enlarger can also be used for making duplicates. Some enlarger heads can be removed and used as a box to hold the slide. Units with built-in filtration are the best, as they allow you to dial-in amount of necessary filtration. You can also use your enlarger to make large format duplicates of your 35mm or medium format originals. Place a sheet of 4X5 or even an 8X10 film in a film holder and expose the film as you would when exposing a paper. No matter which method you want to use, you must experiment to get the best result. Always bracket your shots +/-1/2 stops up to 2 stops in either direction. You can use an ordinary slide film such as Fujichrome or Ektachrome if you have only a few originals that you want to duplicate. Grain is a problem, so use a slow ISO 50 film for best result. Normal films will give very contrasty duplicates. You have to use flash to lower the contrast or overexpose and underdeveloped (pull process) the film. With flash, make a double exposure; one of the original and the second of an out of focus gray card several stops less than the first exposure. You can also overexpose the duplicate by one stop and have your film pull processed by one stop. Duplicating films are much better to use. They are designed to give lower contrast duplicates. Most types are used under tungsten lighting. They come with recommended filtration in 35mm cassette or 100-foot rolls. Kodak Ektachrome duplicating 5071 and Fujichrome CDU (available in 100-foot roll only) can be used with any color slides with great results. For Sheet films, use Kodak Ektachrome 6121 with a 10 sec exposure. Medium format users have only one choice, Ektachrome 5011 available in 70mm (100 foot-roll) only. You need a 70mm film back or a Beattie film holder. The later is a box that holds 70mm films and is placed under an enlarger. Note that one frame must be sacrificed per each shot for precise focus, using Beattie film holder. Experiment with different exposures and filtration with the equipment and films you plan to use. Generally speaking, f-11 gives the best result whether you use your camera or an enlarger. Anything wider can give soft corners, and smaller apertures can cause diffraction and longer exposure times. Keep in mind that for each .10 density of filtration, you need 1/3 stop additional exposure. Your camera meter will compensate for this unless you are using an enlarger or a medium format or large format camera without a built-in meter. Take note of your exposure settings and filtration. It might take a few tries before you get proper results. Once you are happy with your duplicates, repeat the settings that produced the best results.