OVERVIEW

Bo-ming Tong of Conurus Imaging Corporation pioneered the Contax to Canon EF conversion process, thus giving Contax N lenses a new lease on life. Using old manual lenses on Canon EOS bodies is nothing new. With the appropriate adapter the lens can be attached and provides manual focus lens with stop down metering. Conurus’ approach is NOT a “electronically dumb” adapter. It is a true, full-fledge functioning conversion which turns the Contax N auto-focus lens with auto aperture into a Canon EF auto focus lens. Once converted the Contax N lens operates like any other Canon EF lens. No adapters, true auto-focus and a true electronic aperture.

Conurus’ conversion addresses both hardware and software. The lens mount mount is replaced with a custom machined Canon EF mount, custom firmware is loaded into the lens and the electrical contact assembly is replaced. The lens firmware is upgradable (via Conurus) which is good should Canon change their protocols in the future. Mount tolerances are carefully measured and shimmed for proper performance. Focus is calibrated and Bo-ming incorporated a micro focus adjustment feature in the lens firmware, allowing end-users to adjust the lens to their camera. Bo-ming’s craftsmanship and attention to detail is excellent. My lenses have came back looking as good as when they left. The total process took about 4 weeks, but wait times can be longer.

BUILD QUALITY AND LENS HANDLING

Overall I have no issue with the Contax 100N’s build quality. It is a large lens and purpose-built for macro shooting. The lens is solidly built with an all metal lens barrel and mount. The finish seems durable as most Contax N lenses age well (no paint peeling). My only niggle with the Contax 100N is its size. As a portrait and general landscape lens, it is a bit much to haul around. The Contax 100N does feel somewhat nose heavy when mounted on the 1Ds Mark II.

The Contax 100mm N is a large lens because it is 1:1 macro. All the mechanics are internal, so the lens stays a constant size through-out the focus range. Auto focus is slow, but accurate. Most macro lenses are known for slow auto-focus, so the Contax 100N is par for the course. There is no AF / MF switch on the Contax N lens barrels, so to use manual focus on a Canon dSLR, the lens aperture ring is turned to F22 - another unique feature of Conurus’ custom developed firmware.

If buying a used Contax 100N from Ebay or a camera store, make sure the lens includes its lens hood. The Contax N hoods are scarce and used prices can be ridiculous. The Contax 100N has a 72mm filter thread, so Contax 72-86 Metal Ring and Contax #4 Metal hood could be used as well.

LENS PERFORMANCE

The Contax C/Y 100mm F2 Planar has been my favorite lens, and for years I have been trying to find an auto-focus lens that matches the Contax C/Y Planar’s performance. I bought the Contax N 100mm F2.8 Makro-Sonnar to see if it could replace the Contax 100mm Planar. In this context the Contax 100N’s macro performance is not important (to me); I am interested in its overall performance as a general 100mm lens.

What I noticed most about the 100mm Makro is its color palette and smooth graduations. I picked the sample images on the next page because they have a different color palette compared to what I usually find in Canon lenses.  Normally the Carl Zeiss T* multi-coatings are considered to be cooler than their Canon counterparts.