Two enlargers with the same lens can print the same negative quite differently, and the reason is the light above the negative. The head is the biggest choice you'll make on a used enlarger. Here's how the main types differ, what lamps they use, and what to look for when one's for sale.
Why the light changes contrast
A black-and-white negative is made of silver grains, and silver scatters light. If the light comes straight down, as it does through condensers, the scattering pulls light out of the dense areas and the print gets harder. If the light arrives from every direction, as it does from a diffuser, there's less to lose and the print is softer. A. Callier published on this scatter in 1909, and it's still called the Callier effect. Wikipedia notes the full optical explanation didn't arrive until papers by Chavel and Loewenthal in 1978.
How big is the difference? Omega's manual for its C760 lamphouse puts it at about one grade of paper. A negative that prints on grade 2 with a condenser needs grade 3 with diffusion. The same manual says there's no difference in sharpness, because the lens decides that. Color negatives are made of dyes, which absorb light instead of scattering it, so they print the same either way.
Condenser heads
A lamp sits above one or more big glass condenser lenses that focus the light through the negative. Many use a frosted opal bulb, and those are still easy to get. KHB Photografix, a Canadian enlarger dealer, lists the PH211 at 75 watts and the PH212 at 150 watts. Durst's 606 manual notes that a projection lamp gives about half again as much light on the baseboard as an opal lamp of the same wattage, so the bulb choice changes exposure times too. The condensers have to suit the format and sometimes the lens. The Omega D2 has two fixed condensers and a third you slide to a position marked for your focal length, and the Beseler 23C uses its own condenser assembly.
The trade-off is dust. Wikipedia's enlarger article says the condenser's extra contrast "emphasises any negative defects, such as dirt and scratches, and image grain." Beseler's colorhead manual credits condensers with "more apparent definition". LPL sold its 7700 with a triple condenser for printers who, in KHB's words, prefer the extra snap. On variable-contrast paper, a condenser head needs filters in its drawer or under the lens.
Diffusion heads
Here the lamp lights a mixing box or a diffuser, and the negative sees even, scattered light. Omega's manual says diffusion enlargers "tend to suppress grain, scratches and dust in the negative", and Beseler's says a diffusion system gives cleaner prints from dusty or retouched negatives with less spotting. You give up about a grade of contrast, which you can get back with a harder filter or longer film development.
Mixing boxes are sized for the format. Omega supplied its C760 heads with a 35mm box and a 6x7 box. If you print several sizes, check that the boxes for them are there.
Dichroic color heads
A dichroic color head has three dials that slide cyan, magenta and yellow dichroic filters into the beam, and a mixing box blends it. Omega's C760 dials each color from 0 to 200, and a white light lever pulls the filters out for focusing. These heads were made for color printing, and they print black-and-white too. Variable-contrast paper uses emulsions that respond differently to blue and green light, so magenta, which blocks green, raises contrast, and yellow, which blocks blue, lowers it. Beseler's Dichro 45S manual says the head controls contrast "without the need of an additional set of filters." Both makers printed starting settings for Ilford and Kodak papers, and Omega calls its table a point of departure to test.
The catch is the lamp. Color heads use low-voltage halogen lamps made for that head, often fed by a separate power supply. Beseler's Dichro 45S, which fits the 45M series including the 45MX, uses an 82-volt, 250-watt lamp and has its own stabilized supply built in. Omega's C760 uses an 85-watt, 82-volt lamp, and Omega strongly recommended its separate voltage stabilizer on 110-volt units, because line voltage swings shift exposure and color. When we checked KHB's lamp list in October 2026, both lamps were listed out of stock. A color head with a lamp that lights, and its power supply, is the one to buy.
Variable-contrast heads
Some diffusion heads were built just for variable-contrast paper. LPL's VCCE head, which stands for Variable Contrast, Constant Exposure, lets you dial in a grade and keeps the exposure the same at every setting. It has separate channels for Kodak Polycontrast and Ilford Multigrade type papers, and it runs a 12-volt, 100-watt halogen lamp from a power supply. It's built for black-and-white paper. For color, LPL sold a separate dichroic head for the same machines.
Cold light heads
A cold light head swaps the bulb for a coiled fluorescent grid. Wikipedia describes the result as a softer print, with less heat, so negatives buckle less and Newton's rings are less of a problem. Aristo made grid heads to fit enlargers including the Omega B-22, the Beseler 23C, and a D2 model for Omega D-series and Beseler 4x5 machines. These now turn up used, and KHB lists only used ones. Tubes and opal diffusers are specific to the head, so ask for a photo of the tube lit. Look at the seal between the head and the carrier as well. The author of the largeformatphotography.info darkroom primer found his used enlarger leaked light where the cold light head sat on the carrier, fogging his highlights, and fixed it with a rubber gasket. RH Designs marks its StopClock timer as suitable for cold light enlargers, so check your timer's spec sheet says the same.
Which one should you buy?
- Grainy or dusty negatives? A diffusion or color head.
- Want the crisp look and don't mind spotting? A condenser head and a filter set.
- Might try color one day? A dichroic color head with its lamp and supply.
- Only print variable-contrast black-and-white and want it simple? A VCCE-style diffusion head.
- Already have a head you like? Check the lamp, the mixing box or condensers for each size, and the power supply before anything else.
