Introduction
The three Simmon brothers began producing enlargers in the mid-30s and are still in business today (as OmegaSatter). The original company was Simmon Brothers, and the greek Ω symbol was the logo; but over the years the symbol became the name of the product. Enlargers by Simmon Brothers are almost always referred to as "Omega" enlargers.
Omega enlargers typically follow a reliable name scheme: the letter designates the format size of the enlarger (i.e. the largest negative the enlarger can accept); the following number indiciates the model generation. A B size enlarger is larger than an A, a D is larger than both, etc. Typically the higher the number, the more recent the model. E.g. a B-22 is more recent than a B-3.
The letter formats are: "A" (35mm), "B" (2-¼-square), "C" (3-¼-square), "D" (4x5), "E" (5x7) and "F" (8x10).
There are some exceptions, as noted. Marketing departments love to depart from a standard naming scheme, and in some cases, a very popular model enlarger (such as the D5) remained in production after more recent machines were discontinued.
To the best of my knowledge, the XL designation refers to an extended-length column.
I have a few of Instruction Manuals and brochures available for download. 
Quick Comparison
| Model | Mfg | Col. Type | Lens Focus | Focus Method | Baseboard | Notes |
|---|---|---|---|---|---|---|
| B | 1937-1940s | Single Tube | Bellows | Manual | Unknown | The original model inthis series |
| Super B | 1939-1940s | Dual-Rail | Bellows | Manual | Unknown | The smaller sister of the Super C |
| B-3 | 1949-1953 | Triangle | Cone | Autofocus | Unknown | A major revision, first of this series to use autofocus. Sometimes referred to as the Automega B-3 |
| B-4 | 1949-1953 | Triangle | Cone | Manual | Unknown | Manual-focus, non-geared elevation version of the B-3 |
| B-5 | 1953-1955 | Triangle | Cone | Autofocus | Unknown | Revised B-3 chassis to accept the Omega Light head |
| B-6 | 1953-1955 | Triangle | Cone | Manual | Unknown | Manual focus version of the B-5 |
| B-7 | 1955-1973 | Dual-Rail | Cone | Autofocus | Unknown | Revised autofocus system and dual-rail column |
| B-8 | 1955-1974 | Dual-Rail | Cone | Manual | Unknown | Manual focus version of the B-7 |
| B-9 | 1960-1960s | Dual-Rail | Cone | Autofocus | Unknown | Updated chassis specificially designed to accept Chromega color heads |
| B-10 | 1960-1960s | Dual-Rail | Cone | Manual | Unknown | Manual focus version of the B-9 |
| B-22 | 1962-1974 | Triangle | Bellows | Manual | 16x20 (18x26 on XL model) | Offered with both standard and XL column lengths. Originally sold with a condensor head, offered with the Chromega B Dichro head at the end of its run. modern Photography Test Sept 1962 |
| B600 | 1976-1979 | Single Beam | Bellows | Manual | Unknown | Low-end version for beginners and home darkroom use |
| B-66 | 1974-1980 | Single Beam | Bellows | Manual | 16x20 | Replacement for the B-22. Adapters allowed it to take the C-700 or C760 Dichroic heads. Modern Photography Test July 1975 |
| B635 | 1979-1985 | Solid Beam | Bellows | Manual | Unknown | Export, tweaked version of the B600 |
Series Comments
The B series is Omega's most widely-represented, at least in numbers of models. With only a couple of exceptions, it stayed at the 2-¼"-square (6x6cm) format, which made it a favorite for hobbyists and serious amateurs who worked with both 35mm and 120 roll-film, or for 35mm users who liked the fact that these larger models looked more substantial, often had more accessories, and might prove useful for larger work "just in case."
Model Comments
Complete Enlarger (Model B)
Please see my comments in the Other Omega section.
B
Actually the second of the series, if you count the "Complete" model. This was a conventional enlarger: it had a pipe column with a tape-spring counterbalance. Instead of using bellows, it had an adjustable tube for focusing.
Super B
The first of this series to look like a modern Omega; it had a dual rail column. Like the Super C, its big feature was a set of bellows both above and below the negative. The upper set could be used to adjust the negative stage relative to the light source, and thus eliminate the need for different condensors for different film formats.
B-3
The big new feature on this model was autofocus, and Omega sometimes called it the Automega B-3. A specially cut aluminum track fit along the column and a wheel rolled along it. The wheel in turn varied the distance between the lens and the negative stage. The idea was that you could focus once and the image would remain in focus as you shifted the head up and down to change the cropping. This system would show up on various other Omega enlargers, such as the large format D-3. But the B-3 also had rack-and-pinion head-positioning, and triple condensers for various formats—nice additions in any enlarger.
B-4
This was a budget edition of the B-3: no autofocus, no rack-and-pinion head movement, and only two condensers (you had to buy the third one if you wanted to do other formats).
B-5 and B-6
Very similar to the B-3 and B-4 respectively, except that they've been modified to accept the option Omegalite B cold light head, and later the Chromega B color head could be retrofitted to it. The B-5 is autofocus, the B-6 manual. Both have rack-and-pinion head movement.
B-7 and B-8
A major updating; the single aluminum column changed to dual-rail, and the B-7 got a revised autofocus mechanism as found on the D3. The B-8 is the manual-focus version of the B-7.
B-9 and B-10
This was a variant of the B-7 and B-8, respectively, except that they were designed specifically to take the Chromega B and Chromega-Sphere color heads.
B-22
Back to the single-box aluminum column. It was sold for years with the condenser head, but toward the end it could take the Chromega B Dichroic head as well.
B600
This is the B-series version of the C700, a beginner-level enlarger meant to be particularly simple and easy to use. It originally took the Chromega B Dichroic head, but could also accept the C700 Dichroic and C760 Dichroic heads as well.
B-66
The successor to the B-22, it took a redesigned, simpler condenser head, but it could accept the Chromega B Dichroic and (with adapters) the C700 Dichroic and C760 Dichroic heads.
The following unsigned review appeared in Modern Photography, July 1975. It's been slightly edited for brevity.
Specifications: Chromega B Dichroic color enlarger; all negative sizes to 2¼ x 2¼", 16 x 19½" baseboard; 36" Inclined upright; spring-loaded rapid-shift glassless carrier; spring-loaded counterbalanced lamphouse; dichroic filtration range 0-170 cyan, magenta and yellow; 75-watt, 27-volt quartz halogen lamp with built-in dichroic reflector; tapered diffuser in mixing chamber; Infrared and ultraviolet filtration; lamphouse cooling through die-cast heat sink. Other Features: special power supply, Interchangeable lens boards. Price: $315.90; with 48-ln. girder, $335.90.
The new Chromega B Dichroic is a small-format color enlarger at a price comparable with that of plain high-quality enlargers some years back. There are just two questions that need answering. How good is the enlarger and, more importantly, how good are the results it produces?
Basically, if you take an Omega B-22 or Pro-Lab B-66 enlarger and replace the condenser head with a Chromega B Dichroic lamphouse, you have a Chromega B Dichroic enlarger. This means that the familiar inclined girder with its attendant rigidity is, fortunately, still part of the system.
Let's look at the machine mechanically and optically. The model we tested had a 36" (0.9m) inclined upright--but with a new wrinkle. Traditionally, Omega designed their machines with the uprights left in a natural aluminum finish. It looked good, but there was always a slight chance that light bouncing from the easel during exposure could be reflected back on the paper. The new models have the uprights finished in matte black. It may not have the pizzazz of the bright finish, but it is, in actinic terms, preferable and we consider it to be a definite improvement over the older machines.
Loosening a knob on the right rear of the enlarger permits the head to be moved up and down with great ease, thanks to just the right amount of counterbalancing from the single spring-loaded unit at the top of the upright. A large 2" (50mm) knob, also at the right of the enlarger, facilitates smooth, easy focusing via a friction drive against a heavy, solid brass rod; this provides 5½" (140mm) of bellows extension. Loosen two knurled lock nuts and the lens board twists out for rapid, easy interchangeability.
A red filter is mounted below the lens and swings smoothly and easily out of the way. The red filter is as traditional to enlarger design as chrome strips are to automobile design--and about as useful. At Modern, we never use these filters. And we've never met anyone who uses 'em. Modern's editors recommend that the filter be dropped, not just by Omega but by all enlarger manufacturers, and that the resultant cost saving be used elsewhere on the machine for a more significant feature.
Now back to the Chromega's operating controls. Pull a lever forward at the left of the enlarger, and the lamphouse is raised. Position this lever behind a retaining knob, and the lamphouse is locked in the raised position. The carrier may then be removed. It's a simple but effective unit. Light spring-loading separates the plates when the weight of the head is released and the carrier is open to receive the film. Four positioning pins assure perfect image centering. The lower plate is finished in matte black, and four more pins at the ends of the carrier guide the film strip straight and true.
Now to where the action is: the Chromega B Dichroic head. We started by taking it apart, but let's talk about the exterior functions first. Three dials located at the left of the head control (from top to bottom) the cyan, magenta and yellow filters through a range of 0-170. Small rectangular windows with magnifying plastic lenses make reading easy in the dark. The scales are, of course, illuminated and calibrated in units of 1 OCC, while the filtration is stepless.
When we removed the cover of the color head, we saw that two knurled knobs hold down the lamp cover. This makes changing the 75-watt, 27-volt quartz halogen lamp simple.
Inspecting the dichroic filter and mixing box (which you need never do) requires that a small Phillips head screw be removed so the protective cover can be raised. Looking down at the lamphouse, you see the lamp on the left. Just to the right is a slide which holds the heat-absorbing glass in place. Pulling the slide out is a mistake, since, when we did it, the heat absorbing glass immediately fell out of the slide into the lamp compartment. We fished it out with a tweezer and replaced the unit. The three dichroic filters are mounted in individual plates; turning the filtration knobs moves the filters in and out of the light path via smoothly operating cams. Just to the right of the filters is the mixing box, a polyurethane unit that blends and concentrates the light. How efficiently it does this we'll find out later when we test the Chromega's illumination.
But now let's get down to what really counts: alignment, which determines overall sharpness and evenness of illumination. And then we'll move on to matters such as brilliance, rigidity and cool operation. Using our standard Omega alignment tool, we checked parallelism between lens, negative and baseboard, and it worked out like this. Alignment between negative and lens was within 1/8 of a bubble length, while alignment between negative and baseboard was within 1/16 of a bubble length. These figures exceed our alignment standards by a wide margin.
The Chromega B is an extremely cool running enlarger, heat being no problem even with exposures that run four times the reciprocity limit of color paper. But it's easy to make a cool running machine. All you have to do is design a machine having a low level of illumination. Is that what Omega has done? No way. To evaluate the Chromega's illumination system, we first used our Lektra PTM-ta Photometer to measure evenness of illumination, and then we made some color prints.
When we set up our photometer at the center of the baseboard, the level of illumination nearly blew the needle off the scale at the settings we usually use. The difference in illumination between center and edges was within 1/8 stop, while the relative corner-to-corner illumination was virtually dead-on. This is, of course, a very good performance.
Now about making a print. We used our usual test negative, a Kodak Ektacolor Standard Negative Part No. 513412. We made an 8x10 print using the filtration indicated by our color analyzer, which was 40Y + 80M. The exposure turned out to be 10 sec. at f/8. So the Chromega B is a really fast machine, due largely to Omega's efficient mixing box design. Remember that it uses only a 75-watt light source. We have tested ordinary condenser enlargers with no filtration in the light path that didn't do this well.
Why do we make such a fuss over high levels of illumination? Simple. The point at which color papers become subject to reciprocity failure is 60 sec. If a negative is dense and requires high filtration, a dim enlarger will require exposures well over the 60-sec. limit. The Omega head avoids this problem by providing plenty of light to spare.
Now for the final test--rigidity. We test this by placing a beaker of water at the top of the enlarger, giving the enlarger a good hard rap and timing the number of seconds it takes the ripples in the water to disappear. The Chromega B settled down within 5 sec. This isn't bad, but isn't quite as good as the most rigid enlargers we've tested. We attribute this performance to the fact that the usual wooden baseboard has been replaced by fiberboard, which has a bit more flex than heavy plywood.
Everything considered, this is a lot of color machine for the money. It is fast and produces prints of high color saturation, partially due, we believe, to the efficient UV and IR filtration in the system. Equally important is the fact that it was very easy to work with. There were no mechanical hassles or shortcomings. The Chromega B reflects Omega's ability to produce a lot of color enlarger at a moderate price.
B-635
A non-USA product (though it was available in Canada). It's basically a B-600 except for the lamp and condensers, which run on foreign input voltages. Like the B-600, it could take the Chromega B Dichroic and (with adapters) the C700 Dichroic and C760 Dichroic heads (if using USA voltage).