Pentax SMC Pentax 67 75mm f/2.8 AL

Overview

The SMC Pentax 67 75mm f/2.8 AL is the fast wide-normal of the Pentax 67 system and one of the last lenses Pentax designed for it. It arrived in 2001, two years after the Pentax 67II body, as a replacement for the 1989 75mm f/4.5: a stop and a half faster, closer focusing, less distorted, and lighter, at a higher price.^[1] On 6 × 7 the 75mm frames like a 37mm lens on full-frame 35mm, a moderate wide-normal that suits environmental portraits, reportage and landscape work where the 105mm f/2.4 feels tight.

Along with the 105mm f/2.4 and the 55mm f/4, the 75mm AL is one of the three lenses most Pentax 67 users end up carrying, and on the used market it holds its value better than any other 67 wide-angle.^[2]

The AL designation

Pentax used "AL" to mark lenses with at least one aspherical element, in the same way "ED" marks extra-low-dispersion glass and "IF" internal focusing. In the 67 line the 75mm f/2.8 is the only AL lens. The aspherical surface is a hybrid: a thin layer of optical resin moulded onto a spherical glass element, cheaper to make than a ground aspheric and used by every manufacturer from the 1990s on.

An aspherical surface lets a designer correct spherical aberration and distortion with fewer elements than an all-spherical design needs. That is what allowed Pentax to open the 75mm up to f/2.8 without the soft corners a spherical design of that speed would show on a 6 × 7 frame, and to do it in a lens that weighs less than the slower f/4.5 it replaced.

The engraving is often misread. "AL" is frequently typed as "AI" in listings and searches, and the lens turns up for sale as the "75mm f/2.8 AI"; Pentax never made an AI lens, and the letters have nothing to do with Nikon's AI aperture-indexing mount. If you are searching for this lens, try both spellings.

Optical design

Construction	7 elements in 5 groups, one hybrid aspherical element
Aperture	f/2.8 to f/22, 9 blades
Minimum focus	0.41 m (1.35 ft)
Filter thread	67 mm
Weight	about 560 g
Dimensions	92.5 mm diameter, 66 mm long
Mount	Pentax 67 inner bayonet, with 67II-era electrical contacts
Years	2001 to 2009

Despite the f/2.8 aperture the lens keeps the 67 mm filter thread shared by most Pentax 67 primes, one of the practical gains of the compact aspherical design over the older 75mm f/4.5. The lens carries the 67II's electrical contacts for the body's aperture-priority automation and TTL metering, and works on every earlier 6 × 7 and 67 body with whatever metering those bodies provide.

Working notes

Reviewers agree on the essentials. The lens is sharp wide open across most of the frame and very sharp by f/5.6; distortion is low enough to be hard to see in architecture; vignetting at f/2.8 is mild for a medium-format wide and gone by f/5.6.^[1] The nine-blade aperture and the aspherical correction give a smooth background at f/2.8 that the f/4.5 could not offer, which is why this became the portrait wide of the system.

The 0.41 m minimum focus is unusually close for a 6 × 7 wide-angle and lets the lens work as a near-macro for table-top subjects. The focus throw is long and the ring is well damped; the aperture ring clicks in half stops. The lens takes the same bayonet hood family as the other 67 wides and flares less than the older design because of its more modern coatings, but a hood still matters with a front element this size.

Choosing between the 75mm f/2.8 AL and the 75mm f/4.5

	75mm f/2.8 AL	75mm f/4.5
Maximum aperture	f/2.8	f/4.5
Minimum focus	0.41 m	0.7 m
Size and weight	Smaller and lighter	Larger and heavier
Distortion	Low	Noticeable barrel
Used price	High	Low

Choose the AL for available light, for shallow depth of field at 75mm, for close focusing, and for the cleanest geometry. Choose the f/4.5 when the budget matters or for tripod landscape work at f/11 to f/16, where the two lenses are hard to tell apart. The 75mm f/4.5 Shift is a third option for architecture, trading speed for perspective control.

Related lenses

• SMC Pentax 67 75mm f/4.5 — the slower predecessor
• SMC Pentax 67 75mm f/4.5 Shift — perspective-control version at the same focal length
• SMC Pentax 67 105mm f/2.4 — the system's standard lens and the AL's usual companion
• SMC Pentax 67 55mm f/4 — the next step wider
• SMC Pentax 67 90mm f/2.8 LS — leaf-shutter alternative for flash work