Acutar 165mm f/6.3

Overview

The Acutar 165mm 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 165mm is the shortest member of the Acutar line, intended as a normal lens for 4×5. Its 163mm image circle just covers the 4×5 effective diagonal (~155mm), giving modest movement headroom — well-suited to straight-on architectural, product, and reproduction work where view-camera movements stay small. The lens mounts in a Copal 0 shutter.

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 modest rise/fall and shift 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	modest (~8mm spare)
5×7	no	image circle below 5×7 diagonal (~210mm)
8×10	no	image circle far below 8×10 diagonal (~310mm)

Related lenses

• Acutar 210mm f/6.3 — most popular Acutar focal length; comfortable normal for 4×5
• Acutar 300mm f/6.3 — long lens for 4×5, normal for 5×7, minimal-coverage 8×10