Introduction
The Charles Beseler company began in 1868 making scientific and lab equipment, and began producing enlargers in 1953. Beseler is one of the two dominant manufacturers in the USA. Their enlargers (along with Omega) were frequently found in schools and rental labs; a great many students learned how to print on a Beseler enlarger. While not the least expensive, they are typically rugged, no-nonsense machines that are built to last.
Beseler has a naming scheme for most of their enlargers which describes the features of the machine. E.g. a 45MXC is a 4x5 enlarger chassis with a motorized colorhead and extra support truss.
- Two-digit number — the max size of the negative it can accept (e.g. 23 is 2cm x 3cm, 66 is 6cm x 6cm, 45 is 4x5 inches, etc.)
- M — electric motor to raise and lower the lamphouse
- C — Beseler colorhead (filter drawer type)
- R — Resistrol unit (variable voltage regulator)
- X — Rear support truss (extra reinforcement)
- AF — Automatic focus
- B — Beslite (flourescent cold-light head)
- AG — Beseler-Agra colorhead (continuously variable filter type)
I have a few of Instruction Manuals and brochures available for download. 
Quick Comparison
| Model | Mfg | Size | Col. Type | Col. Height | Head | Focus Method | Baseboard | Price | Notes |
|---|---|---|---|---|---|---|---|---|---|
| 23C | 1955 - tbd | 2-¼ x 3-¼ | Dual column frame | 36" | Interchanglable: condenser, variable-contrast, and dichroic color | Manual | 25 x 16" | Modern Photography Test March 1972 | |
| 23CII | 1960s thru early 1980s | 2-¼ x 3-¼ | Dual column frame | 36" | Interchanglable: condenser, variable-contrast, and dichroic color | Manual | 25 x 16" | $400 | |
| 23CIII | Current | 2-¼ x 3-¼ | Dual column frame | 57" (XL version) | Interchanglable: condenser, variable-contrast, and dichroic color | Manual | 25 x 16" |
Series Comments
Like the 45, the 23C is a long-running series that Beseler tweaks from time to time, but doesn't need to make major updates for. I'll write specific model comments as I learn the, but right now I'm very limited in what I know about this chassis.