Canon Ef 135mm f/2.8 Softfocus, as you might have guessed it, is one of very few lenses that implements a shifting aspherical glass elements. When shifted, this aspherical element can cause varying degrees of soft focus. The lens was released back in 1987, so the Softfocus feature is probably less appealing today since most users can use post-processing software like Adobe Photoshop to add this effect. Other then this rather unusual feature, Canon EF 135mm f/2.8 is a regular medium telephoto lens that competes with dozens of similar medium telephoto lenses produced by various other manufacturers. Priced at about US$280 (as of February 2008) the lens remains within reach of mainstream photographers.
The optical construction of the lens consists of 7 elements in 6 groups (with a single aspherical element as mentioned above). The build quality is not particularly impressive - lens barrel is made of plastic and the focusing ring is pretty narrow (albeit smooth). The lens has a dedicated control ring that along with the softfocus switch on the side of the barrel lets users operates the softfocus mechanism (2 modes, which I would call 'soft' and 'even softer'). The lens incorporates an AFD AF motor, but also allows users to focus manually assuming they switch the lens into manual mode using an AF/MF switch found on the side of the barrel.
The lens is pretty light and reasonably compact, weighing mere 390g (13.8oz) and measuring 60 x 98mm (2.7 x 3.9in). Thanks to the internal focusing mechanism, the overall length of the lens does not change since the internal cams do not extend during focusing. The minimum focusing distance is 1.3m (4.3ft) and the minimum aperture level is f/32. Like all of Canon's AF lenses, Canon Ef 135mm f/2.8 Softfocus does not have a dedicated aperture control ring and all aperture settings have to be set directly from the camera. The lens accepts screw-in type 52mm filters.
The factory box includes Canon EF 135mm f/2.8 Softfocus lens, front and rear caps, manual and registration card. The lens carries EF designation, meaning it was designed for full frame cameras, so on an APS-C body with 1.6x crop sensor, the field of view of the lens is equivalent to that of a 216mm lens on a full frame body. The lens is compatible with Canon's Gelatin Filter Holder Adapters III and IV as well as with Canon's Extension Tubes EF 12 II and EF 25 II.
|Lens Composition||7 elements in 6 groups|
|Angular Field||18 degrees|
|Focusing Action||AF/MF, AFD
|f-stop Scale||f/2.8-f/32, camera-controlled|
|Lens Hood||ET-65III (included)
|Lens Case||LP1016 (included)|
Canon EF 135mm f/2.8 Softfocus did not produce particularly impressive results in the field - while center image quality was pretty good across the aperture range, borders were noticeably soft on both APS-C as well as FF cameras. Unfortunately, stopping down the lens did not improve image resolution around borders. Furthermore, the lens produced images that were washed out and lacking contrast. Color reproduction was more on the warmer side, which is typical for most Canon lenses.
The lens showed its 'ancient' design - AF system was way too slow and way too noisy. The system hunted quite often and not just in dark, but pretty much in all lightning conditions. The soft focus operation is pretty transparent - you can switch the lens into soft focus mode (mode 1 or 2) by first pulling the SF switch and then rotating the soft focus ring. Once you position the soft focus ring in the mode you want to use, all shots you'd take will be blurred automatically. Fortunately, AF system will continue to work even in the soft focus mode, so basically overall operation of the lens does not really change.
The lens did not show any particular strength in handling bokeh. Fore/background objects were sufficiently blurred and contrast transitions were more or less smooth, however, OOF highlights carried distinct highlights around edges and background objects showed occasional double edging.
The lens showed minor vignetting on a full frame Canon 5D with wide open aperture. This is rather unusual for a telephoto lens of this focal length and hence is a bit disappointing. Fortunately, vignetting is reduced with stopped down aperture and by f/5.6 it is all but gone. And on APS-C body the lens showed no vignetting throughout the tested aperture range (not surprising since the APS-C sensor has a smaller coverage). The lens fell prone to color fringing pretty much across the frame on both full frame as well as APS-C bodies (see front of the chair on the right side of the image crop below). On a somewhat positive side, flare as well as distortion were basically non-existent.
|Canon EF 135mm f/2.8 Softfocus image gallery...|
Please note that MTF50 results for APS-C and Full-Frame cameras are not cross-comparable despite the same normalized [0:1] range used to report results for both types of cameras.
Canon APS-C: Canon EF 135mm f/2.8 Softfocus showed a rather mixed performance in the lab. Center image quality was very good throughout the tested aperture range. This was quite encouraging early on, but miracles ended here. Border quality was mediocre from f/2.8 all the way through the rest of the tested aperture. Performance around borders stays at about the same level, but consistency is not really a benefit here. Unfortunately, there's not much to report - there are no peaks and huge drop-offs in performance as the overall quality remains consistent at all apertures. The lens is capable of producing outstanding 11in and OK 16in prints, which is not very exciting for a medium telephoto lens. Conclusion? Well, while center performance is pretty decent, these days it is hardly sufficient. Especially for a medium telephoto lens.
With the exception of borders at f/2.8, chromatic aberration on an APS-C body was more or less under control. At f/2.8 border CA averages ~1.2px, which is somewhat high for a telephoto lens. As you stop down the aperture, CA is reduced to a more manageable ~0.9px at f/4, dropping even further at smaller apertures. CA in the center was not much of a problem, averaging ~0.5px throughout the aperture range.
Here're 100% crops comparing image borders taken at f/2.8 and f/8.
Canon FF: Considering that the lens did not perform that well around borders on an APS-C camera, my expectations were already reduced. The lens still performed quite well in the center, showing slightly better performance in the f/2.8 through f/5.6 range. However, border quality was as mediocre as with an APS-C body - performance here remained pretty much on the same level throughout the tested aperture range. Not really surprising since FF puts even more 'stress' on borders then an APS- C sensor. Conclusion? Did you expect a miracle here? I certainly did not, so overall performance is still kind of 'iffy'. Not much else to add here.
Chromatic aberration on a full frame Canon 5D was slightly better then on an APS-C body (thanks to the larger sensor). Center CA averaged ~0.4px with wide open aperture, dropping to even lower levels with stopped down aperture. CA around borders averaged ~1px at f/2.8 and dropped to ~0.8px in the f/4-f/11 range.
Here are 100% crops, taken with a full frame Canon 5D, comparing image borders at f/2.8 and f/8.
When looking for an alternative to Canon's EF 135mm f/2.8 Softfocus, you need to first decide whether the soft focus capability is important to you. If it is, then there are no modern mainstream alternatives and you would have to expand your search to alternative mounts. However, if you are interested in a telephoto, then this is a totally different story. Canon currently offers two excellent telephoto primes in its lineup - Canon EF 135mm f/2L USM and Canon EF 200mm f/2.8L II USM. Both lenses offer excellent image quality and sport superb build mechanics, however they also cost quite a bit more. A third model, Canon EF 200mm f/2L IS USM was introduced recently (late 2007) and by all accounts is an as impressive performer as its two older brethren. Outside of the Canon lineup, you might want to take a look at Sigma's Macro 105mm f/2.8 EX DG lens, which offers an excellent balance between quality (performance and build) and price. Finally, if you are using an APS-C camera, you might also want to explore Tokina's AT-X Pro D AF 100mm f/2.8 Macro, which also offers very respectable overall performance and superb build quality.
There is nothing special about Canon EF 135mm f/2.8 Softfocus that should make you drool about it. Ok, I mean there's nothing special about its performance, since technically speaking this is a pretty special lens due to its native soft focusing capability. However, I highly doubt that anyone would want to trade off image quality for a feature that can be obtained in post-processing stage. As mentioned above, in this day and age, we should have higher expectations from a medium telephoto lens and users should spend some time exploring alternatives.