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Field Tests

Handling: For a medium telephoto, Contax Carl Zeiss Planar T* 100mm f/2 is a fairly compact and well balanced lens - on a larger Canon 5D, the center of weight falls close to the lens's aperture ring, making hand-holding the combo with one hand quite doable. However, on a smaller cameras, the lens tips over the camera and the weight puts more strain on the wrist. The focusing ring rotates about 220 degrees when going from the infinity to 1m, giving you enough rotational distance for precise focusing. The lens has an engraved DOF scale, which can help you preset the lens using hyper-focal focusing distance and use your combo as a 'point and shoot on steroids'. The aperture ring is well damped and clicks into position firmly. The f/22 level is one exception - on the original Contax cameras, you could achieve automatic aperture control whe you switched the lens to f/22, so the aperture ring locks in this position much firmer then at any other level and requires quite a bit of force to move the ring to a different level.

Like any alternative mount lens, the 100mm Contax Planar does not pass any aperture or focal distance down to the camera - the original Contax bodies had mechanical coupling with the lens, which allowed for an automatic aperture setting along with the aperture level recording and proper metering. With the lens mounted on a camera via an adapter, you have to rely on stop down metering and record current aperture setting on a piece of paper. Some of the modern adapters now allow programming focal length as well as maximum aperture setting, which I highly recommend you do to improve the metering accuracy - the metering systems of most modern digital cameras typically underexpose the image at wider apertures and overexpose it at smaller ones, so adding the maximum supported aperture setting does help the system provide correction during metering.


Resolution: Generally speaking, when I first started testing the lenses 2+ years ago, I selected a set of cameras (top notch at that time) for testing lenses and stuck with them throughout all my tests. What I found out over time that some of the lenses are capable of capturing a magnitude higher level of detail then even the best cameras of that time. Now, the sensor and camera technologies have advanced quite a bit over the last two years and I am starting to think that I should upgrade my test equipment so that I can stress better some of the more capable lenses. Contax Planar T* 100mm f/2 falls into this camp - the lens seems to outpace both of my standard APS-C and FF Canon bodies (Canon Digital Rebel XTi and Canon 5D) in terms of resolution. At least I cannot see any noticeable quality difference when using this lens on either of these cameras and any of the tested aperture settings. The only change in resolution seems to occur when shooting at closer distances but even then the difference seen by the naked eye is almost eluding. Bottom line is that from now on, I will add another full frame body with higher resolution sensor (either 1Ds Mk3 or Canon 4D Mk2) to supplement the tests of certain lenses that seem to out-resolve the older cameras. Stay tuned for the update to this section.

DOF & Bokeh: As discussed in the past reviews, the look and feel of DOF and bokeh are highly dependent on a number of factors, including the focal length of the lens, the focusing distance to the subject and the aperture setting to name a few. The images below show what you can expect from the lens in different situations, particularly at the minimum and moderate focusing distances and wide open and stopped down apertures. As you can see from the sample shots, the lens produces the shallowest DOF and the heaviest background blur at the minimum focusing distance with wide open aperture. Not that surprising. However, the amount of background blur is not as high as one can expect from a number of other lenses, particularly those that have a closer minimum focusing distance. Specifically, if you compare the results taken with Carl Zeiss Planar T* 100mm f/2 and Canon EF 100mm f/2.8L IS USM Macro (which was reviewed a few days earlier), you will notice that despite its slightly slower maximum aperture, the Canon lens actually produces smoother background. It seems that in lenses with identical focal length, the focusing distance actually plays a larger role in DOF and bokeh rendering then the maximum aperture. But keep in mind that the rendering, as mentioned earlier, will depend on a number of additional factors not tested here. One would expect in particular, that the distance to the background plane would affect how heavily the background will be blurred - the farther away the objects fall outside of the hyper-focal distance, the heavier they will be blurred in the picture.


DOF @ 1m

ISO 100, 1/4000, f/2, 100mm (Canon 5D)
ISO 100, 1/200, f/8, 100mm (Canon 5D)

DOF @ 3m

ISO 100, 1/3200, f/2, 100mm (Canon 5D)
ISO 100, 1/200, f/8, 100mm (Canon 5D)


And so while Contax Planar T* 100mm f/2 did not necessarily produce the absolute smoothest out of focus background blur in these limited tests, the overall feel of separation between the in-focus and out-of-focus areas remained still quite pleasing (again at wider apertures and close to moderate distances). The feel was definitely affected by the lens's superb resolving and tonal reproduction capabilities. Plus the fact that the lens did not show any visible double-edging in OOF areas and mostly neutral lightning of OOF highlights.


ISO 200, 1/3200, f/2, 100mm (Canon 5D)


Flare: Carl Zeiss Planar T* 100mm f/2 fell prone to some flare in certain situations, which is not that surprising, considering that most lenses would fall short when stressed hard enough. Particularly, when pointing the lens towards a strong light source, be aware that you might end up with some artifacts. In the sample pictures below, you can see how Planar fared in such a situation. The sun was peeking over the roof of the building, hitting the lens at ~50 degrees. At f//2, you can clearly see both color shifts in the image as well as flare/ghosting. Stopped down apertures fared somewhat better - at f/8 the image exhibits lower overall contrast levels, but no signs of glare or ghosting.


ISO 400, 1/1250, f/2, 100mm (Canon 5D)
ISO 400, 1/80, f/8, 100mm (Canon 5D)


Vignetting: Generally speaking, amount of light falloff in modern days should not be of any major concern to photographers because of ohh so many available tools that can correct this issue. Post-processing vignetting correction is the most typical, but some of the newer digital cameras recently started adding built-in vignetting correction mechanisms, which further simplify things. So as long as the lens does not completely darken the corners as if you're shooting through a pinhole, then vignetting should not be a major deciding factor in choosing a lens. When it comes down to Carl Zeiss Planar T* 100mm f/2, the lens shows noticeable vignetting on a full frame Canon 5D with wide open aperture, but the degree of falloff is not particularly different from other fast medium telephoto lenses out there. On an APS-C sized canon, the lens takes advantage of the smaller sensor and shows very minimal vignetting even with wide open aperture. And once you stop down to f/4, vignetting basically becomes non-existent on either FF or APS-S camerass.


Vignetting @ f/2 - FF vs APS-C


Color Reproduction: Color reproduction has historically been probably one of the strongest points of Carl Zeiss lenses. This is also often the main reason cited by users for adopting these old lenses to modern digital cameras. Contax Planar T* 100mm f/2 is easily one of the best examples in the Contax lineup. as it shows very well balanced, almost neutral color rendition - there is a very slight shift towards blues, which leaves a slightly cooler impression then with comparable lenses from Canon or Sigma. Colors remain saturated but not overdone and make pictures look quite lively. And the lens captures very fine grained transitions in tonality quite well, both in shadows as well as in mid-tones. Generally speaking, the lens  clearly is capable of transmitting a much wider color gamut then what Canon 5D's 12bit A/D can handle. Oh well, another reason to drool for a 32bit A/D if and when it becomes available...


ISO 100, 1/4000, f/2, 100mm (Canon 5D)