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It seems like 135mm focal length is going through a decline in popularity among photographers. At least if we judge the popularity of a particular lens by the number of lenses currently being manufactured for various camera systems. Then the 60s, 70s and even 80s were easily the golden age of 135mm, with pretty much every camera and lens manufacturer offering at least one, and in many cases two or even three variants of a 135mm prime. Carl Zeiss Jena had Sonnar 135mm f/3.5 and f /4, Pentacon had 135mm f/2.8 and 135mm f/4, Schneider had 135mm f/3.5, Olympus had 135mm f/2.8 and f/3.5, Pentax had 135mm f/2.8, the list goes on... Even Carl Zeiss itself used to offer three versions of 135mm lenses - Planar T* 135mm f/2, Sonnar T* 135mm  f/2.8 and Tele-Tessar 135mm f/4. The Tele-Tessar was discontinued during Rollei SL35 era, but the other two carried on into Contax/Yashica mount. These days however, only Canon, Nikon and Sony offer 135mm lenses in their lineups, with the latter one actually offering a Zeiss Sonnar design, as mentioned earlier. It seems that the focal length is being squeezed out by more popular 100mm or even 85mm on the shorter end, and by 200mm on the longer end. There is, after all, very little reason to own both 100mm and 135mm since the focal length difference is not that significant for all practical purposes.

These days, Contax Sonnar 135mm f/2.8 has become a started alternative lens for many gear-heads. As any alternative lens, the 135mm Sonnar does require special handling and hence is not really suitable for the masses. Firstly, this is obviously a manual focus lens, and since most modern cameras (particularly APS-C type) have rather small and dark viewfinders, with no focusing aids, the focusing action can be rather tedious. You can rely on your vision, or use live view if your camera has one, but I would recommend getting an AF confirmation adapter - it will help you improve the accuracy and speed up focusing. The focusing action itself is  reasonably accurate - the focusing ring rotates for about 180 degrees from the infinity to the closeup, with higher precision in the shorter focusing range. Secondly, even if you end up getting an AF chipped adapter, you will still have to manually stop down the aperture since there is no coupling between the lens and the camera. The stop down metering process does take some time getting used to and it obviously slows down your shooting since you need to first focus the lens, then stop it down to desired aperture setting, meter and only then shoot. You might seriously consider getting a dedicated spot meter, particularly since majority of cameras overexpose shots with fully manual aperture lenses stopped down to smaller apertures.

On its old Contax web site, Carl Zeiss states that the 135mm Sonnar is "Outstanding for landscape photography, flora and fauna studies, portraits and others where a telephoto effect is desired without the undesirable flattening of perspective prevalent with longer focal lengths'. 'Huh?' you might say and your reaction is correct - basically what Zeiss was saying about this lens is that you can use it for pretty much any purpose, but because this is a wider end of telephoto focal range, the view perspective does not get flattened that much as with say a 300mm lens. Well, that does not really increase our understanding of this particular lens since any 135mm prime would deliver less perspective flattening then a 200mm, a 300mm or a 500mm. What I would have preferred Zeiss say is that the lens delivers excellent image resolution with corner to corner sharp results. The lens was indeed pretty sharp in the field and behaved quite well on both APS-C as well as FF Canon cameras. Center image resolution was universally outstanding, whether you shoot at f/2.8 or f/11. Borders were reasonably sharp with wide open aperture and outstanding from f/4 all the way through. Also, there did not seem to be any noticable difference in how the lens performed at closeup vs infinity focusing. Notice me saying 'reasonably'. This is because while you can notice a little bit of softness around borders at wider apertures, for practical reasons this should not ruin your pictures, even if you leave them as is with no sharpenning applied during post-processing.

Speaking of the perspective flattening. If you are planning to use the lens for portrait type of work, which is the most common use for 135mm lenses like Sonnar, the flattened perspective in combination with shallow DOF would typically improve the 'feel' of bokeh - the out of focus area, blurring it better and making the subject in focus stand out . If the lens is also capable  of delivering high contrast levels in the focused areas, you would get the feeling of the subject 'popping' out of the picture. The so called '3D feel' of the lens sought by so many alternative lens users chasing after Zeiss and Leica lenses. Now, Sonnar T* 135mm f/2.8 does not deliver a particularly thin DOF like one might see in faster lenses - the shot below simulates the DOF at f/2.8 and close to the minimum focusing distance. However, since the lens does flatten the perspective, you can, depending on the situation, achieve a decent looking bokeh, as can be seen in the photos of flowers in the sample image gallery. Notice however, that the bokeh 'looks' different in the three flower shots. This is because the different focusing distance to the flower. Guess which of these was done at the minimum, close to minimum and  not-so-close to minimum focusing distance?

 

ISO 400, 1/160, f/2.8, 135mm (Canon 5D)

Continuing on the subject of bokeh. The shot below demonstrates a relatively simple scenario when the lens is used at the close to minimum focusing distance and wide open aperture. You can notice that the out of focus highlights have rather pronounced, bright edges, with few of them having a light greenish tint. This is likely because the lens was over corrected for spherical aberration, which is not that uncommon in optical designs optimized for end-to-end frame sharpness. The effect is not very pronounced, so it should not ruin your pictures. Finally, on another positive note, you can see in all samples that there is no visible sign of double edging around out of focus areas, which can become quite distracting and ruin the tranquility of even the best bokeh.

ISO 400, 1/100, f/2.8, 135mm
ISO 400, 1/100, f/2.8, 135mm (Canon 5D)

 

Flare handling, which typically is more of a problem in wide angle lenses, could be considered normal with Carl Zeiss Sonnar T* 135mm f/2.8. In extreme conditions, the lens does show flare pretty much throughout the aperture range, but a rare lens would do much better here. Shots above demonstrate what happens if you point the lens towards the sun and don't use the built-in hood. In this case, the sun was positioned right above the picture frame, with sun rays peaking through the tree branches and hitting the lens at ~55 degrees. As one would expect, you get reduced contrast and blown out highlights as well as light streaks and spots, particularly at wider angles. Hopefully you are not going to compose your pictures this way, but if you do, use a built-in lens hood at least.

 

ISO 100, 1/500, f/2.8, 135mm
ISO 100, 1/60, f/8, 135mm

 

Vignetting on a full-frame camera was well under control - at f/2.8 vignetting was pretty minimal and basically non-existent once stopped down to f/4. Vignetting on an APS-C camera was non-existent throughout the aperture range. For a telephoto lens this does not come as a big surprise.

 

Vignetting @ f/2.8 - full frame vs 1.6x crop
Vignetting @ f/2.8 - full frame vs 1.6x crop

 

As mentioned earlier, one of the most often quoted by alternative users reasons for going after Contax lenses is their superb color reproduction. That is where a good lens can really show its colors, pardon the pun. A combination of high contrast in focused areas, high resolution and accurate color reproduction is what can give your photos what is often described as that true 'Zeiss' or 'Leica' look and feel. And while many lenses out there showcase solid resolution capabilities, not that many handle color reproduction well, with Sonnar T* 135mm f/2.8 lying somewhere in the middle. Color reproduction generally speaking was quite decent, and images did carry enough contrast in shadows and midtones to make your pictures look lively, but I did not notice anything particularly outstanding with this lens. It just seemed that Sonnar is capable of handling most situations well enough for the majority of users, but there was nothing that would make it stand out here from many other quality lenses out there. Still. for a 20+ year old design and sub US$300 lens, the results are quite good overall.


ISO 100, 1/1600, f/2.8, 135mm (100% crop)
ISO 100, 1/1600, f/2.8, 135mm (100% crop)