The Asahi Pentax MX is a compact mechanical SLR that supports a wide range of budget-friendly lenses. It’s compact enough to fit in a pocket (with the appropriate lens) and boasts a robust construction. If you’ve used the Olympus OM-1, you'll likely appreciate the Pentax MX. It's highly functional — stripped down of any unnecessary features — and is both small and lightweight. Additionally, it features an all-metal body at a very competitive price point. The Pentax MX enjoys popularity with numerous favorable reviews. However, no camera is flawless, and the MX comes with a few points to be aware of. This review will discuss the essential features and known problems. I will also offer alternatives of compact mechanical SLRs if you're looking for a quicker shutter, an even more minimalistic design, or a more compact size (they do exist¹).
In this review: Technical specifications, design and ergonomics, build quality and known issues, Pentax K-Mount lenses, alternatives to the Pentax MX, pricing, and where to purchase it. Support this blog and access premium features with GOLD memberships!¹ — For a half-frame camera.
The technical specifications highlight the size, weight, all-metal construction, all-mechanical shutter, and minimalist features that define the Pentax MX. This camera was in production from 1976 to 1985 for a duration of nine years. It is compatible with all K-Mount lenses (except for newer FA-J and DA lenses that lack aperture rings). The kit lens is the SMC Pentax-M 1:1.7 50mm.
Focusing is achieved with a single-lens reflex (SLR) design that includes an interchangeable focusing screen, a 0.97x magnification, and 95% coverage. It features a comfortable finder for its size that only slightly clips the edges of the actual frame. A depth-of-field preview lever and a self-timer (operating between 4 to 12 seconds) can be accessed via a lever on the front plate.
The shutter is a focal-plane model with speeds ranging from 1 second to 1/1000 second, plus a bulb setting. Shutter speeds are displayed in small black text in the viewfinder on the right. The metering is center-weighted uncoupled through-the-lens type, with an EV range of 1-19, suitable for film ISO ratings between 26 and 1600 (without compensation). Exposure hints are provided in the viewfinder using green, yellow, and red LEDs. Battery operation is optional (only for the uncoupled meter), requiring two LR44 batteries. The camera has both FP and X sockets as well as a hot shoe; sync speed is 1/60 second. Dimensions are 135.5mm × 82.5mm × 49.5mm (5⅓” × 3¼” × 2”), and it weighs 495g / 17.5oz.
The design and ergonomics of the Pentax MX make it one of the few SLRs that could potentially fit in a pocket, albeit in a jacket or coat. When equipped with the 40mm Pentax-M 1:2.8 lens, it protrudes just over 2cm/⅘”. While it's not so light that it goes unnoticed, being constructed from brass, it’s considerably lighter than many SLRS from its era, as well as various modern plastic DSLRs. The MX feels exceptionally solid when held, with perfectly fitting components and high-quality finishing. While the design could be further refined to match the meticulous craftsmanship of brands like Leica or Voigtländer, the MX is designed as a high-quality working camera, which it undoubtedly is.
However, due to its compact size, this fully-mechanical system may pose challenges if any repairs are needed. In practical use, it operates smoothly. Despite being entirely manual (with exposure assistance), I could easily use my Pentax MX with one hand. It has a decent grip, although its blocky design is prominent. With a small lens, focusing, adjusting the aperture, and changing the shutter speed can be done without using the left hand. Both aperture and shutter speed indicators are visible within the viewfinder, allowing you to keep the camera at eye level between shots.
Though not practical for daily use, I did swap the lens on my Pentax MX for a homemade pinhole setup for a lighter profile. However, be aware that shooting solely with the right hand is possible, but may not feel entirely comfortable or easy. Additionally, the shutter speed display in the viewfinder requires good lighting to be seen, as the text appears in black against a transparent background, similarly to the aperture readings that project directly from the lens into the viewfinder.
The viewfinder of the Pentax MX is relatively bright — more so than that of the Olympus OM-1 (its main competitor) — but
The Asahi Pentax MX is a compact mechanical SLR that works with a wide range of budget-friendly lenses. Its size allows it to be pocketable (depending on the lens), and its construction is extremely durable. However, no camera is without flaws, and the MX has some aspects you should be aware of. In this review, I will discuss the key features and known problems. I will also recommend a few alternative compact mechanical SLRs if you prefer a quicker shutter speed, a more minimalist design, or an even smaller size (which is indeed available¹).