Pentax SMC Pentax-L 43mm F1.9

Pentax SMC Pentax-L 43mm F1.9

The SMC Pentax-L 43mm f/1.9 is the only lens Pentax ever built for a mount other than its own, a Leica thread mount (M39/LTM) version of the company's celebrated FA 43mm Limited optic. Carrying the suffix "Special" rather than "Limited," it was produced in a single small run and remains one of the more sought-after oddities among rangefinder collectors. Production was split between two finishes, with 800 lenses made in chrome and 1,200 in black, for a total of 2,000 units [1]. The 43mm focal length is unusual on purpose: it corresponds to the true diagonal of the 35mm frame, so Pentax marketed it as the most genuinely "standard" standard lens.

Optically the Special shares the seven-element, six-group design of the K-mount FA 43mm Limited, mounted in a barrel adapted for a rangefinder body. The lens is rangefinder coupled, so it focuses through the camera's coupled rangefinder rather than by guesswork, and being a screw-mount lens it can be used on Leica M bodies and other M-mount cameras through a simple LTM-to-M adapter [1]. It uses Pentax's Super Multi Coating (SMC), has a nine-bladed diaphragm, and takes 40mm filters. A practical limitation noted by users is its one-metre minimum focus distance, longer than many native Leica lenses, which constrains close work. The barrel is metal and noticeably larger in diameter than typical compact LTM lenses such as the collapsible Elmar, a consequence of retaining the SLR optical layout.

Because it was sold almost entirely in the Japanese market in a small quantity, the Special trades well above the K-mount Limited and is frequently encountered as a boxed collector item with its dedicated 43mm/50mm accessory viewfinder. Originality points worth checking are the matched finder, the front and rear caps, and the box, all of which affect value. Collector price guides place clean examples substantially higher than the common K-mount version, reflecting the rarity rather than any optical superiority over the SLR lens [1].

Optical qualities

Rendering Because the Special uses the same optical formula as the FA 43mm Limited, its imaging character can be inferred from that well-documented lens. The 43mm is known for accurate, neutral color that leans neither warm nor cool [2]. Reviewers describe a lens with pleasing rendering that suits documentary and everyday subjects, though the following observations come from the SLR version and should be read as a guide rather than a measurement of the LTM barrel.

Sharpness Central sharpness is strong even wide open, with the most demanding detail resolved well; optimum sharpness is reached around f/5.6, only marginally better than f/2.8. Wide open at f/1.9 the corners soften and the lens is at its least crisp [2].

Bokeh and transitions Out-of-focus rendering has been called somewhat busy, attributable in part to the middle-of-the-road focal length; it smooths noticeably when focused close and stopped to around f/2.8, but the lens is not primarily a background-blur tool [2].

Distortion and vignetting Geometric distortion is minimal, measured as only a trace of barrel distortion. Corner shading is also slight, on the order of about a third of a stop wide open and negligible by f/2.8, with no vignetting reported on the full 35mm frame [2].

Aberrations The chief optical weakness is chromatic aberration, which is slightly pronounced, alongside the corner softness seen wide open [2].

History

Development and Launch The 43mm Limited was the first of Pentax's hand-assembled FA Limited primes, conceived around the idea of a true normal lens matching the 35mm frame diagonal. The Leica-mount Special followed as a limited rangefinder edition, produced in the year 2000 [1]. It is the sole example of Pentax offering one of its prized Limited optics in a competitor's mount, and it was aimed at the Japanese rangefinder enthusiast market that had grown around then-current screw-mount cameras.

Production Evolution The Special was a closed run rather than an evolving product. The only documented variation is finish: chrome and black barrels, in the 800/1,200 split noted above [1].

Special editions The Special is itself effectively the special edition. No further factory sub-variants, military versions, or regional renamings are widely documented; the meaningful distinction is simply the silver versus black finish.

Collector Notes Buyers should verify the matching 43mm/50mm finder, both caps, and the original box, as complete sets command a premium. The lens is physically broader than typical LTM optics, which can feel slightly awkward on the smallest screw-mount bodies but sits comfortably on M-mount cameras via adapter. The one-metre minimum focus is inherent to the design and not a fault. Published reference data for this lens is thin and some specification listings vary between sources, so confirm finish, mount, and completeness from photographs before purchase.

Sources

• [1] CollectiBlend. Asahi: 43mm (4.3cm) f1.9 SMC Pentax-L Special (M39) Lens Price Guide. https://collectiblend.com/Lenses/Asahi/43mm-f1.9-SMC-Pentax-L-Special-(M39).html
• [2] Imaging Resource. Pentax 43mm f/1.9 Limited SMC P-FA. https://www.imaging-resource.com/lenses/pentax/43mm-f1.9-limited-smc-p-fa/review/