Ollinger's Guide to Photographic Enlargers: Elwood Enlargers

Introduction

Elwood Pattern Works made a number of enlargers; a few are small but their bread-and-butter was large-format (5x7 and up).

Quick Comparison

Model	Country	Era	Format	Baseboard (inches)	Head	Focusing	Autofocus	Column	Ref
AM-3 Miniature	USA	Late 1940s	2-¼ x 3-¼"	n/a	Reflector	Rack & pinion	No	Single post	1
BM MIniature	USA	Late 1940s	1-7/8 x 2-¼"	n/a	Single condenser	Helical	No	Single post	1
S2 Studio	USA	Late 1940s	5x7	n/a	Reflector	Rack & pinion	No	Single post	1
SP-2 Special	USA	Late 1940s	5x7	n/a	Double Condenser	Rack & pinion	No	Single post	1
5x7 Autofocus	USA	Late 1940s	5x7	n/a	Reflector	Bellows	Yes	Curved column	1
C-2 Commercial	USA	Late 1940s	8x10	n/a	Reflector	Rack & pinion	No	Curved column	1
8x10 Autofocus	USA	Late 1940s	8x10	n/a	Reflector	Bellows	Yes	Curved column	1
Mapping Enlarger	USA	Late 1940s	8x10	n/a	Reflector	Bellows	Yes	Curved column	1

Key

Era: It's nearly impossible to get actual production year spans; I've provided this simply to give an idea of when an enlarger was in production.

Focusing:

Bellows means that the lens stage is connected to bellows that expand and collapse, and the bellows are typically moved via a wheel using friction (as opposed to using rack & pinion gears).
Helical focusing means a collar around the lens is turned, and the lens housing is threaded so that the lens moves up and down.
Rack & Pinion means that the lens stage moves up and down via a knob that turns gears.
Tube means that the lens is set into a tube that moves up and down (as opposed to bellows).

Autofocus: not to be confused with what we think of as autofocus today; these enlargers don't focus themselves. What they do is offer a sort of tracking control so that once the image is focused, it stays in focus as you change the elevation of the head for cropping.

Column: all columns are assumed to be vertical unless oblique is noted. Oblique columns (i.e. angled forward) are nice at higher head elevations because the image won't expand back across the column post when the head is at the top of the post. On smaller enlargers this wouldn't be a problem, but at larger magnifications (and with lenses with shorter focal lengths), this can become a concern.

References

Modern Photography magazine, December 1949