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What makes a good Canon EOS / Contax adapter for Canon dSLRs

 

CHOOSING A GOOD CANON-Contax C/Y ADAPTER

 

POPULAR AGAIN!

Canon’s full-frame dSLRs revived interest in classic 35mm manual focus lenses. Some photographers want to use their favorite lenses from years past, other photographers are experiencing these lenses for the first time. Whether searching for a hidden treasure at a bargain price or looking for ultimate wide-angle lens, a good adapter is critical for maximizing the lens’ performance potential. If an adapter based solution sound unattractive, a whole range of Zeiss ZE lenses are available in a native Canon EF Mount. The new Zeiss ZE lenses eliminate the need for an adapter and provide full auto-exposure and focus confirmation. Complete EXIF data is also embedded into the RAW or JPEG file as well. The new Zeiss lenses have updated lens coatings and newer optical designs.


These days I only use Leitax adapters. The next 3 pages detail all the woes typically found with cheap adapters. Leitax adapters cost more, but they are best option available today (in my opinion). For more information, see my Leitax review. The review is for the Leica R / EOS adapter, but the set-up is exactly the same as the Contax / EOS adapters. The following pages apply to the types of adapter typically found Ebay for $40-$80. These adapters can be handy to have on hand, but I do not bother with them anymore due quality & performance issues. Note - I do not receive any financial compensation or consideration from Leitax.

WHAT MAKES A “GOOD” LENS ADAPTER?

Finding the right adapter requires some patience. ‘Google’ the adapter brand and see what other people have to say about the adapter. Look user reviews in photography forums such as Fred Miranda or the Manual Focus Forum. Most likely the results will be mixed, but some will have more negative press than others. There tend to be conflicting opinions because there are many variables involved. Some of the common technical issues include:

  1. Proper Flange Thickness - Adapter thickness is one of the most common issues. In this case “thickness” refers to the adapter metal between Contax lens and Canon EF mount when the lens is mounted. This is the adapter’s “flange”. Zeiss designed the Contax C/Y lenses for a specific distance from the rear exit pupil to the film plane. If this distance is not maintained, then the design has been compromised. If the adapter flange is too thick then the lens may not focus all the way to infinity. If the adapter is too thin, then images may look out-of-focus. Aside from mis-focused images, other nasty things can happen - such as fringing (ie - chromatic aberrations commonly called “CA”) or halation (image looks sort of glowy or ghostly). Matters can get even more complicated if the lens uses a floating element design.


  2. Some adapters are poorly designed. Others are well designed, but fabrication variances cause problems, such as poor quality control during plating process leading to increased thickness. For a Contax Carl Zeiss T* lens used Canon EF or EF-s dSLR, the correct adapter (flange) thickness is ~1.425mm. 1.425mm is NOT an absolute. In some cases a thicker or thinner may work better. There are many reasons why varying adapter thicknesses may work - some lenses aren’t as sensitive to adapter thickness, the Contax lens may not be in proper calibration due to age (use), the Canon dSLR body may not have been assembled to strict enough tolerances (ie - the Canon 5D mirror box) or maybe the Contax lens was not assembled to such tight tolerances.

  3. Uniform Adapter Thickness - All adapters will have high and low spots in their flange thickness. Anything within +/- .004mm tolerance should not adversely effect performance. However, if an adapter’s thickness is already at the edge of acceptable thickness, then the plating may be the added bit of extra material needed to turn an otherwise acceptable adapter into a bad adapter.