Acutar 210mm f/6.3

Overview

The Acutar 210mm f/6.3 is a four-element Tessar-type large-format lens manufactured by Ilex Optical Co. of Rochester, New York. The Acutar series spans seven focal lengths from 165mm to 508mm, all sharing the same f/6.3 maximum aperture and the same general optical design — a Tessar derivative with a somewhat wider angle of coverage than the traditional Tessar formula, comparable in concept to Kodak's Commercial Ektar series. Calumet sold these same lenses rebadged under their Caltar name; Acutar and Caltar specimens are interchangeable.

The 210mm is the most popular focal length in the Acutar range — a comfortable normal lens for 4×5 and a marginal normal for 5×7. Its 240mm image circle covers 4×5 with generous headroom (~85mm spare on the diagonal) but only modestly clears the 5×7 effective diagonal (~210mm), making it usable on 5×7 with limited movements only. The lens mounts in a Copal 1 shutter. On the used market, 210mm Acutars and Caltars are common; Caltar-branded specimens are generally noted as well-made examples of the design.

Optical design

Four elements in three groups, Tessar derivative. The somewhat wider angle of coverage versus a classical Tessar makes the lens better-matched to LF cameras that exploit movements. Performance is at its best at typical large-format working apertures (f/16–f/32).

Format coverage

Format	Covers?	Movement headroom
4×5	yes	generous (~85mm spare)
5×7	marginal	~30mm spare — minimal movements only
8×10	no	image circle below 8×10 diagonal (~310mm)

Related lenses

• Acutar 165mm f/6.3 — the next Acutar focal length down; normal for 4×5 only
• Acutar 300mm f/6.3 — long lens for 4×5, normal for 5×7, just covers 8×10