Zeiss Vario-Sonnar T* 24-85mm f/3.5-4.5 N (Contax N to Canon EF) Review / Test Report
Lens Reviews -
Canon EOS (APS-C)
Page 1 of 3
Lens kindly provided for testing purposes by Markus Stamm!
The Carl-Zeiss Vario-Sonnar T* 24-85mm f/3.5-4.5 is the 2nd converted Contax N
lens for Canon EOS tested here in Photozone. The mount conversion can be ordered
via Conurus. It is
not a cheap procedure but thereafter the lens behaves like a native Canon EF
lens including AF, a camera-controlled aperture and (mostly) valid EXIF data.
The lens is a bit slower than f/4.5 @ 85mm and interestingly it is recognized as
86mm f/5 in EOS land here.
The Zeiss 24-85mm was the standard "kit" lens sold with the Contax N1 and
Contax N Digital. Naturally this didn't translate to "cheap" regarding the
high-end target market although it was a relatively affordable item
by the Zeiss standards of the time. It was also the first N-mount lens
to feature an ultrasonic AF drive.
As usual we'll have a look how it performs on an APS-C DSLR (EOS 350D).
I'm aware that some of you may have wished a test on a full format DSLR but
these tests will start based on the successor of the EOS 5D.
Typical for most Zeiss lenses the build quality is very good thanks to high
quality materials. However, the lens uses a dual-cam design - two inner lens tubes
extend when zooming towards the long end of the zoom range - and this sets limits
to the build tolerances. Unfortunately the lens seems to suck in lots
of air ... and dust. Used samples are never in perfectly mint condition in
Thanks to an internal focusing (IF) mechanism the physical length remains constant
during focusing (but not during zooming).
The zoom ring operates a little stiff. Manual focusing feels smooth but it is
a rather imperfect implementation because the mechanism doesn't interlock
You may notice that the EOS 350D looks rather dwarfish in comparison - it is
a relatively short but "fat" lens thanks to the big front elements and the
huge 82mm filter thread.
As mentioned the Zeiss features an ultrasonic AF motor including FTM (full-time
manual control in one-shot AF mode). It's not a speed daemon
but reasonably fast and relatively accurate. Besides the
mount conversion Conurus faced one little obstacle - Contax N lenses have no
AF/MF switch (selected on the camera). However, he found a workaround for this: you
have to set the (otherwise useless) aperture ring to the smallest aperture for
manual focusing. This may be an unusual thought but it works just fine.
Interestingly the new firmware (v2.+) has a new "AF micro-adjustment" feature - similar
to the new EOS 1D III it is possibly to do a focus fine-tuning so if you're experiencing
a front/backfocus problem you can easily correct this yourself (regardless of the
|Equiv. focal length||38-136 mm (full format equivalent)|
|Equiv. aperture||f/5.6-f/7.2 (full format equivalent, in terms of depth-of-field)|
|Optical construction||14 elements in 12 groups inc. 2x fluor crown and 2x aspherical elements|
|Number of aperture blades||7|
|min. focus distance||0.5 m (max. magnification ratio 1:6.7 @ 85mm)|
|Dimensions||90 x 71 mm|
|Filter size||82 mm (non-rotating)|
|Hood||supplied, petal shaped (snap-on)|