Darkroom: Editing and Focusing Optics

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Light Boxes and Loupes

For previewing black-and-white, color negative or slide film, there is nothing more convenient and comfortable than being able to examine images through a high-quality loupe atop a precise, color-controlled light box. In this way, a photographer can determine which of a series of images is the best composed or sharpest, or which contains subtleties of light or expression that the others lack. It also becomes easier to judge color, contrast and overall impressions.

A light box can be an inexpensive $10 plastic box with an incandescent bulb or a wall-mountable, high-priced stainless steel unit with balanced 5000K illumination. Light boxes serve multiple uses in many different disciplines, for photographers and editors to doctors, artists and government agencies or philatelists and numismatists. The range of choices in light boxes is as varied as the different types of cameras available on the market. Size, construction, power supplies and color temperature are only some of the variables to consider when buying a light box. It all comes down to how demanding you choose to be in critically evaluating your images. For simple, rapid-editing purposes, it may not be necessary to purchase a high-end box. However, when critical demands are required and a higher degree of precision is necessary, then you should consider making an investment in a light box with more professional features. Color temperature, durability and other features such as ease of lamp change, carrying facility and storage possibilities should all be considered when making a purchase.

As with many technological accessories, with a light box, you tend to get what you pay for. The less expensive ones may not possess the evenness of illumination along the entire viewing surface, while the more expensive ones remain equally bright edge to edge. Some are thinner than others, making portability more practical and easier. Some have carry handles, some don't, while others are either supplied with their own slipcase or are designed to fit inside briefcases. Still others are meant to be wall-mounted much like the traditional “shadow boxes” that doctors use to look at X-rays.

Be careful! Light boxes emit white light that is deadly to printing paper! One approach you might consider is building a light box into your countertop. In that way it will be flush with your working surface and out of the way. You could even rig up a foot switch to turn the light box on and off with your foot while you keep your hands free for handling the enlarger or your printing paper, kind of like the clutch pedal on a motorcycle.

A loupe is the optical device you look through to examine your image critically on the light box. It is normally held close to the eye and rests upon the image while it’s on the light box. As is the case with light boxes, there are many different styles of loupes to choose from, with a wide variety of loupes to suit every film format. For example, for a 35mm frame, a 4x loupe is generally recommended for normal use. However, an 8x loupe for the same image will yield a more magnified image and allow closer inspection for sharpness and detail. Loupes can also be of the “zoom” type. These loupes function like traditional zoom lenses on cameras. The lens can be adjusted to accommodate the area of the image that needs to be inspected.

Most good loupes will come with two “skirts”—a clear skirt for examining contact sheets or prints and an opaque skirt for examining slides and negatives when using a light box. The clear skirt allows ambient light to penetrate its side for illuminating photos. The opaque skirt blocks any extraneous side light and only allows the rear-lit illumination from the light box to pass through to the eyepiece. Some loupes come with separate interchangeable skirts while others come with two attached, interchangeable sliding skirts.

You will also find loupes made from inexpensive plastic, while more heavy-duty models are constructed from higher-quality metal.

For the amateur or professional photographer seeking to improve his or her craft, a light box and loupe are strongly recommended for the darkroom and studio.

Grain Focusers and Magnifiers

Few of us have eyesight sharp enough to see effectively in the dark. If we were nocturnal marsupials, it would be a different story, but since we are human, our eyesight is often weak or faulty in low light. There are some printers who have been printing for so long that they are accustomed to seeing in the dark and can rack an enlarger up and down until the image is sharp on the easel without the use of a focusing aid. However, for the rest of us, a grain focuser is cheap insurance to make sure the image will be sharp when it’s developed.

Once the print is centered on the paper, viewing it with a grain focuser will help you achieve proper focus. An area of the projected image is selected (generally a highlight, as these tend to show up as dark areas on the printing paper and are easier to see) and the focuser is placed over that spot on the paper in the easel. With your eye pressed against the eyepiece, you rack the enlarger up and down with fine movements until the magnified grain particles inside the focuser look sharp.

Grain focusers come in different sizes and degrees of magnification. A good one should have an adjustable eyepiece (diopter). This will adjust to the degree of magnification that is correct for your eyes.

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