Classic Lens Satisfaction, Made Compact for Mirrorless

Visit a used camera store today and you won’t find nearly the number of classic lenses generally available just a few years ago. The reason is that mirrorless camera shooters are buying these lenses up and rediscovering the joy of using them with the variety of adapters available for these cameras. Classic lenses can provide a unique look to images, the build quality is excellent, and they feel great to use — especially the speed and precision of direct, mechanical manual focus. And the visible focus aids in mirrorless cameras (like focus peaking and split-screen zooming) make that manual focus even more precise and intuitive than was ever previously possible with these lenses, even on the original cameras for which they were designed.

The downside of using an older lens originally designed for an SLR camera is that the optics need to accommodate a big gap between the lens and sensor (or film) for the SLR mirror, called “flange focal distance”. Even rangefinder lenses have a somewhat long flange focal distance. But a lens designed for a mirrorless camera can get much closer to the sensor, which allows its optics to be much smaller at the same level of image quality. So the CM33 takes inspiration from the usability and build quality of classic manual lenses — lessons refined over a period of decades — but brings those lessons to a modern optical design specifically for mirrorless that doesn’t force you to carry around the bulk of a bigger lens and an adapter.

The CM33 uses a fully custom in-house mechanical design with a priority on excellent build quality and feel. It includes a focus ring that connects your hand directly to the motion of the optics through precision machined aluminum and brass parts — not the indirect, laggy electronic focus-by-wire often used in autofocus lenses that are switched to “manual”. The result is focusing that is perfectly smooth and incredibly precise using digital focus aids, especially using our Focus Finder feature.

We want the CM33 to be a truly great photographic tool that can be used and enjoyed for many years. So we have built our mechanical prototype parts on our in-house CNC lathe and mill — the same machines we plan to use for final production of these parts. This means we can tune and optimize the design of our parts and assemblies specifically for the machines’ extraordinary capabilities and precision. It also lets us minimize the number of parts typically required when designing for mass-market production methods, putting more functionality into fewer parts. This minimizes variations from copy to copy of the CM33 and delivers a wonderfully solid feeling in use.

Exceptional Optical Quality in a Pancake Package

The CM33 uses a fully custom and proprietary optical design, developed in-house specifically for the Fujifilm X-mount, Sony E-mount, and Canon M-mount systems. Because these three systems are virtually identical in sensor size and flange focal distance, one lens design can work for all three without compromising either size or performance. Only the bayonet mount itself is different between versions of the CM33 for the three systems.

The result of our year-long optical development of the CM33 is a unique 5-element lens design that produces image quality on par with some of the most highly-regarded compact prime lenses available today, but in an even more optimized package. It’s a pancake lens that lets you carry it on your mirrorless camera anywhere, but without the performance compromises usually taken to achieve that size.

We chose a 33mm focal length because — for the APS-C format the CM33 is designed for — it’s precisely equivalent to the classic 50mm full frame focal length that is wonderful for portraits, street photography, or other general artistic or casual shooting. We worked hard to achieve a maximum aperture of f/2 within the CM33’s compact body — fast enough for low-light usage and capable of shallow depth of focus with pleasing bokeh. This combination of 50mm focal length and f/2 maximum aperture describes some of the most historically important lenses in photography, like Leica’s groundbreaking Summar in the 1930’s and their enduring Summicron. The reason is simple: it's fast and flexible, providing a natural view on the world in a wide variety of conditions.

Our design was fed with copious real-world testing and evaluation that we have performed over the past year, including:

  • Measurement of camera sensor angular chromatic sensitivity curves to ensure we avoid angular roll-off and optical cross-talk that causes color-shifted vignetting near the corners of the image
  • Characterization of cover glasses and filters in camera bodies, to ensure these are correctly compensated for in the optical design
  • Lab and photographic benchmarking of MTF, distortion, chromatic aberration, bokeh, and more on a wide variety of well-regarded prime lenses to ensure we set our performance bar high

Using our own internal optical design techniques developed over years working in the field, we’ve been able to define a design that is optimized for true photographic performance, not the typically-published metrics of performance like oversimplified MTF curves. And through our established American optics manufacturing partner, La Croix Optical, we have access to world-class glasses, coatings, and processes, all nearby within the US.  We were able to work closely with them to optimize our design to take full advantage of their production capabilities refined over decades making precision optics for medical, military, scientific, and industrial systems.

For example, we modeled in software the effect of specific microscopic variations from the ideal lens shape that are introduced in manufacturing and we use those variations in our design to actually correct optical aberrations — rather than increase them — without introducing greater design complexity that would drive up size and variation between lenses. In effect, we’ve been able to get performance that normally requires use of aspheric lenses, without having to use these difficult to manufacture elements. These kinds of techniques are typically reserved for military-grade optics, but we used the same tools, techniques, and suppliers to achieve the CM33’s remarkable size and performance.

We have posted a variety of lab test images as well as real world photographs here so you can see the performance of the CM33’s optics for yourself. We think the results are fitting with the best tradition of lenses that allow instinctive capture of both the detail and feel of a variety of scenes at any aperture — from evocative scenic shots to intimate portraits to engrossing macro images. The CM33 is extremely sharp, exhibits very little chromatic aberration or distortion, and introduces only a mild amount of natural vignette. We think the images it captures are exceptional, especially for a lens of this ultra-compact size.

Amazing Macro Close-up Capability

Another advantage of the CM33’s unique design is incredible close-up capability. Many lens designs sacrifice close focus capability to reduce optical or mechanical complexity, forcing the use of add-on macro adapter rings or a dedicated (and typically large) macro lens. But the CM33 naturally allows you to get within just 5.5 inches (140mm) of your subject, making it flexible enough to capture virtually any subject.