Adapting Zeiss Contax
Zeiss Contax 2.8/60 Makro-Planar being remounted in EF

Previously, I had written about the advantages of Zeiss Contax lenses being repurposed for modern cinema use. This article aims to go into further detail about these lenses and how to go about picking and adapting your lenses.

Zeiss' vintage line of SLR lenses for the Contax system was first produced from 1975 and finally discontinued thirty years later in 2005, when it was replaced with their ZE and ZF (now ZF.2) 'Classic' lenses for Canon and Nikon mounts. As a result, they share a number of similarities and could be considered the forefather to the Classic lenses.

Zeiss produced a number of different lines for the Contax system, however the only one of use to us is their Contax/Yashica line, also known as C/Y, RTS (the name of the Contax SLR) or simply their SLR lenses. C/Y refers to the name of the mount, just like today's EF or PL. The other Contax lines Zeiss had were the 645 (medium format), G (rangefinder) and N (a different, electronic mount). You don't want these, they won't work.

The C/Y line was produced in two versions: AE and MM. AE was simply the earlier production models, whereas MM is more recent - 1984 onwards. The AE models are split into AEG and AEJ. This simply refers to Germany or Japan - the country of manufacture. They were first made in Germany (and are marked as 'Made in West Germany') before production was moved to Japan. All MMs are made in Japan, and are therefore MMJs.

There is no difference in build quality or design between AE and MM lenses. In fact, the only noticeable difference is that the MM lenses have their last aperture number (usually 16 or 22) printed in green, whereas the AE is in white. (AE or MM is never actually mentioned anywhere on the lens.) Image quality should be identical between the AE and MM too. Some people report the flare varies slightly (due to slight changes in the T* lens coating), though optically they're just as good as each other. Officially, only the 2.8/25, 2.8/28 2/135, and 2.8/135 were improved, otherwise optically AE and MM should be equally impressive.

The biggest difference between AE and MM however, and probably the only one that should really have any influence on which you chose, is the shape of the aperture. Both the AE and MM lenses have circular apertures (and therefore circular shaped bokeh) when wide open, as the aperture blades are fully retracted. The MM, when stopped down, will have a regular shape, dictated by the number of blades - six blades produces a hexagonal shape, nine blades produces a nonagon etc.

Zeiss Contax 1.4/50
Zeiss Contax 1.4/50, AE version demonstrating ninja star aperture. From left to right; f/1.4, f/2, f/2.8, f/4

The AE lenses however, due to the way the blades overlap and are rounded off at the very ends, on their second and third stop (counting wide open as the first stop), produce 'ninja-star' bokeh. From the fourth stop onwards, regular polygons like the MMs are produced. Which you chose is purely personal preference. Some people think it's crazy, whereas some (like myself) think that this unique signature looks fantastic! Below are two examples, both shot with the 1.4/50 at an aperture of f/2.

Adam Baroni in Streetfighter: Ryu
Adam Baroni in Streetfighter: Ryu

This first screenshot is an extreme example where the ninja stars are more apparent, caused by candles in the background.

Zeiss Contax demonstrating ninja star bokeh
Andrew Coppin in 2:AM

The second screenshot here is perhaps a more representative example, where the ninja stars are so subtle to be almost unnoticeable. The highlights in the background here are caused by reflections. Also worth noting is how smooth and organic the bokeh is. Remember, 'bokeh' does not refer to the 'bokeh balls' (the highlights you can see in both of these examples), but the quality of the blur itself. Most shooting scenarios will render the ninja stars somewhere between these two examples, depending on how hard the point of light is. Car headlights or fairy lights for instance will create quite sharp, defined ninja stars.

Once you've chosen and acquired your new Zeiss Contax lens(es), you'll want to adapt them to a more useful mount. There are plenty of adapters on eBay, however I would not recommend them. They're made with poor tolerances and as a result, not only do they exhibit a lot of play between the lens and the camera, but infinity focus may well be compromised. These cheap adapters have even been known to result in the lens falling off the camera during use! Invest in a decent mount from Leitax. Whilst not as cheap as the eBay counterparts, they are far superior in every way. Furthermore, they're essentially new mounts for the lenses, as opposed to just adapters. Depending on the lens in question, the new mount may fit right over the top of the existing C/Y mount, or it may involve disassembling/removing part or all of the original mount. It can be done at home or there are companies and individuals who can perform the remounting for you.

You're now set to start shooting with your new glass. You'll soon be hooked and addicted to the look they give you... and will soon be planning your next lens to buy. It's perfectly functional to keep using them as-is; the all metal construction and long, smooth focus throw make them a pleasure to use. The aperture is still 'clicked' however and so aperture pulls aren't yet possible. By disassembling the rear of the lens to get to the aperture mechanism, it is possible to de-click them.

Further modifications that can be undertaken include installing a geared focus ring. There are many companies and solutions that produce lens gears, however most have a 'join' at some point around the circumference. The join must be positioned in such a way that it does not interfere with a follow focus at any point during its full rotation. Alternative solutions include seamless lens gears, machined from various plastics. These are machined to spec and have a very snug fit. Similarly, I have begun 3D printing gears for my lenses. Both my 3D printed ones and the machined gears are installed by heating them up, allowing the material to expand ever so slightly and be more malleable, permitting them to just slip over the end of the lens. They cool, contracting and gripping the lens barrel tightly - leaving a semi-permenant, seamless lens gear.

Very recently however, Zeiss themselves have come up with an elegant, very well engineered solution to seamless lens gears - that are easy to install and can be removed at will. Their lens gears have a second ring which can be twisted to tighten or loosen. Not the cheapest solution, but certainly amongst the best.

And the final modification some people undertake for cine use with Zeiss Contax lenses is standard size hard fronts. Screwing into the filter thread on the front of the lens, these metal rings ensure a consistent diameter across the whole range of lenses. This permits the use of same size caps, but crucially, maximum compatibility with matte boxes and their doughnut rings; blocking light from entering the rear of the matte box which could otherwise bounce off filters and cause unwanted reflections.

If, after a while of using your Zeiss Contax lenses and decide that you want to upgrade to a PL camera perhaps, or maybe you want a 'true' cinema lens, with consistently sized bodies, accurate witness marks and apertures measured in T stops, GL Optics completely rehouses existing Contax (plus Leica, Sigma and other) lenses. Whilst you'd be paying a similar amount to had you bought a set of Zeiss CP.2s or Canon CN-E primes to begin with (and the point of Zeiss Contax was that they're more affordable!), they're the ultimate solution if you want a true cinema lens but can't live without the Contax look. Worth noting however, is that not all Contax lenses are suitable for rehousing; their advertised set includes the standard speed (f/2.8) lenses as opposed to the super speed (f/1.4 and f/2) lenses for many of the focal lengths, and I have heard there may be some compatibility issues with AE lenses. For more information, contact them directly.

Check out Part Two, comparing the Contax line to other Zeiss lenses, both new and old.

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