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 - and now Canon users have a whole new [to them] line of auto-focus lenses to choose from. Using a Contax C/Y lens, or a Hasselblad, or a Rollei, or even Leica-R lens on the Canon EOS bodies is nothing new. Buy the appropriate adapter and you have a manual focus lens with stop down metering. Conurus’ approach is NOT an adapter. It is a true conversion - turning a Contax auto-focus lens with auto aperture into a Canon EF mount lens. Once converted the Contax-N lenses operate just like any other Canon EF lens. No adapters, no need for manual focus, no stop down metering. Contax fans can now have Zeiss quality on their Canon cameras - and without compromise.

THE CONVERSION

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 news if Canon decides to change their protocols in the future. Mount tolerances are carefully measured, and if needed shimmed for proper performance at infinity.

Part of the conversion process includes calibrating the lens’ focus. Bo-ming calibrates the lens by testing it on a Canon 1Ds. The 100mm focuses perfectly on my 1Ds Mark II, which was one my big concerns. If focus needs adjustment, Bo-ming incorporated a micro focus adjustment feature in the lens firmware whereby the end-user can adjust the lens to their camera.

The process is not as elegant as Canon’s new micro focus adjustment, but end result is the same.

Bo-ming’s craftsmanship is excellent - the lens came back looking as good as it did before its journey. The lens feels and acts like any other Canon EF lens on the Canon 1Ds Mark II. The total process took about 4 weeks.

LENS PERFORMANCE

The Contax 100mm Planar has been a star performer on the Canon 1Ds, Canon 1Ds Mark II and now Canon 1Ds Mark III. For years I have been trying to find an auto-focus / auto-exposure lens that matches the Contax C/Y Planar’s performance. I love the 100mm Planar, so an auto focus equivalent would be heaven. Part of the 100mm Planar’s “look” is its color rendering, the micro contrast, the tone curve and resolving power. The 100mm Planar’s micro-contrast gives foliage a wonderful texture, the tone curve renders nice shadow detail and Zeiss’ resolving powers are well known already. Part of the reason I bought the Contax N 100mm F2.8 Makro-Sonnar was to see if it could be that elusive 100mm Planar replacement.

The Contax 100mm F2.8 N Makro-Sonnar is a macro lens, so sharpness is a given. All macro are lenses are sharp. For my needs the 100/2.8 N’s macro performance is not critically important; I am far more interested in its overall performance as a general 100mm lens - and whether or not it could be a replacement for the manual C/Y 100mm F2 Planar. What I have  noticed most about the 100mm Makro is its color palette and smooth graduations. I picked the images on this page as samples because they have a different color palette compared to what I usually find in Canon lenses - especially the image to the left. The pools of blue are very pleasing to my eyes. Normally lenses with the Carl Zeiss T* multi-coatings are considered to be cooler than their Canon counterparts, so that could be a factors in the 100mm Makro’s color reproduction.

When comparing a Contax lens to a Canon L lens, I think the cooler colors is generally true statement; however, I do not think the Zeiss lenses are “cooler” in terms of poor color reproduction. I find their color rendition closer to the actual scene, whereas Canon’s greens and reds tend to be a bit over-saturated (or a bit too vibrant). Sometimes the Canon color palette works, sometimes not. I like the Canon colorings for sunsets, but not for portraits. Looking at the blue image, notice the double image bokeh (background blur) - mainly the stems in the lower right hand corner. This is fairly common with the 100/2.8 N and one area that I wish was better. When shooting the test images in this review, most of time the lens was pointed towards the sun - flare does not appear to be an issue for the 100/2.8 N.

The next two pictures (next page) were also selected for their color. Purplish magentas tends towards a red with a Canon L lens such as the 135mm F2.0 L. I like using Canon lenses during sunsets because their color rendition usually works well with the evening sun. In contrast the Contax 100N produce a wonderful array of subdued purples and magentas.

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