The Darkroom
Care And Feeding Of Enlargers Part I

Photos © 2001, Frances E. Schultz, All Rights Reserved

Most enlargers look much the same: a tall column, with the lamp and negative holder at the top, and a baseboard at the bottom. But given that a cheap, used enlarger with a good lens will, unless badly out of alignment, outperform a brand-new, state of the art enlarger with a bad lens, why do some enlargers enjoy near-legendary status, while others are scorned and despised?

Partly, build quality. A well made and well maintained enlarger will last almost forever, and be easy to use throughout its life. But different kinds of light sources require different maintenance and different kinds of negatives. Get the maintenance and the negative right, and you can produce excellent prints: fail to maintain the enlarger, or mismatch the light source and the negatives, and you will find it hard to get good prints at all.

Light Sources
Most modern enlargers are the diffuser type: the light is bounced around in a mixing chamber (basically, a white box) for diffuse light. "Cold cathode" enlargers use fancy fluorescent tubes behind a diffuser screen for a still more diffuse light, while "condenser diffuser" types use a big, diffuse light source above (or behind) a condenser for a rather more directional light. "Pure" condenser enlargers with a point light source provide the most directional light of all. The four drawings make the different kinds of light sources clear.

Different light sources give different contrasts, even from the same negative on the same paper. The cold cathode will be least contrasty; the diffuser, a little harder (typically less than half a grade); the condenser diffuser, harder again (a grade or so harder than the cold cathode); and the point source condenser, hardest of all (maybe two grades harder than the cold cathode).

The exact figures depend very much on the design of the head, but if the condenser diffuser gives a perfect print on Grade 2 paper, the cold cathode may require Grade 3 (or more) and the point source Grade 1 (or less). If you want to use Grade 2 paper for the majority of your prints--which is a good aim point--then you need to develop your negatives to suit the light source. If you gain or lose contrast at one stage (the light source), you have to make it up at another (the negative or the paper).

Getting Level
Caring for an enlarger is hardly onerous. Once it has been set up properly, it is just a matter of keeping it dry and dust free. Setup consists of two things: leveling/ parallelism, and making sure the illumination is even. Both the light source and the baseboard should be parallel to one another and (preferably) dead level. Leveling is actually less important: it just makes checking parallelism easier. Lack of parallelism means that your prints will not be sharp all over because one side of the paper is further from the lens than the other.

Some top of the line enlargers have bubble levels built-in, along with leveling feet. If yours doesn't, keep a small bubble level in your darkroom to check alignment every now and then. If the baseboard is level, but the head is out of alignment, look for an adjustment screw somewhere near the arm which attaches it to the column. Provision of adjustments for parallelism is one of the big advantages of a top-flight enlarger. If the baseboard is not level, pack it out with something which will not slide or shift, or place it on a more level surface.

The white spot is the sensor; note how, when metering the corners, the meter should always be oriented the same way radially. Failure to do this may result in anomalous readings.

Even Light
Next, check for evenness of illumination. This can be affected by a number of different factors including bulb position, condenser setting, condenser cleanliness, mixing chamber condition, the wrong condenser or mixing chamber, or something as simple as an under-lens filter holder swung part way under the lens.

To measure evenness of illumination on the baseboard, use a light meter with a flat receptor. Take the head part way up the column, high enough to make it easy to use the meter. Read the illumination in the center, then at each edge and at each corner. The drawing makes this clear: obviously you can read in any order.

Try to make sure that the points you read are the same relative distance from the lens. There will be some falloff. The extreme corners may be 1/3 to 1/2 stop darker than the very center, directly under the lens. This is normal. But all corners should read the same. If they don't you will need to make some adjustments.

Check the simplest things first. Make sure nothing is between the lens and the baseboard. With condenser diffuser enlargers, make sure the bulb is centered and at the right height. Make sure condensers are spotlessly clean. The mixing chamber in a diffuser enlarger needs to be clean as well. When the illumination from my Meopta Meograde head became uneven, a new mixing chamber solved the problem. The Styrofoam material becomes gray and dirty after a few years, especially if the enlarger sees heavy use.

A condenser or mixing chamber which is meant to cover 35mm format (generally a 50mm lens) will not cover medium format (an 80-105mm lens). You can use a medium format condenser or mixing chamber with 35mm, but exposures may be longer.

Check the condition of your lens. Make sure that it is scrupulously clean. When buying used enlarger lenses make sure they are clean with no scratches and fungus.

Get Sharp
To get the sharpest prints, test your lens at all apertures. Print a negative with lots of detail all the way to the edges. The widest aperture will rarely if ever give you sharpness all the way out to the edges. Stop down until you find the first aperture which is sharp all over. Then check the smaller apertures. Diffraction limitation means that if you stop down too far, sharpness begins to fall off again. My Meopta 50mm f/2.8 lens performs best at f/5.6 and f/8. If my exposure times become inconveniently short, I will use a neutral density filter rather than stopping down more.

Once you have your enlarger(s)--and they do breed in dark places--set up properly, the only thing you need to do is keep it/them clean and dust free. Kaiser enlargers come with their own plastic covers. A black trash bag (slit up one side if need be) makes a serviceable cover. Cover lenses when they aren't being used, and store them in bubble cases. In a humid darkroom, a packet of silica gel in the bubble case will help prevent fungus.
Keep the whole darkroom clean. When you sweep or run a vacuum cleaner, let the dust settle before you start printing again. Wipe down surfaces with a very slightly damp cloth. In my next darkroom article, I'll talk about matching negatives to light sources. Until then...Happy printing!

nterchangeable Heads
Some enlargers accept interchangeable heads; others have fixed heads. A few even accept third-party heads, usually cold cathode, color diffuser, or variable contrast. Most independent heads are first quality but they are not cheap. Before you consider replacing an old enlarger, find out what is available in the way of upgrades. The Charles Beseler Company, for example has special kits available for upgrading some models.

Cold Cathode Mystique
Cold cathode enlargers have a certain mystique attached to them, and are said to give the closest results to a contact print. I used a cold cathode before I realized they were supposed to be anything remarkable, and I can't say I found it particularly magical. Often, too, they don't work too well with variable contrast papers because the light from many cold cathode sources is disproportionately rich in blue light. There are however a few special variable contrast cold cathode heads that have separately controllable blue-rich and green-rich tubes.

Use The Best Lens You Can Afford
The quality of the enlarger lens you use has much more affect on your prints than the enlarger itself. In general, a modern multi-coated lens has more internal contrast than an old lens.

Internal contrast as well as sharpness is influenced by the number of elements in the lens. With enlarger lenses you generally have a choice of three, four, or six glass lenses. A three or four glass lens will often be adequate for enlargements up to about 4x to 6x, but if you want to enlarge 10x or 15x, a six glass lens will normally give better sharpness.

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