The Canon EF 135mm f/2.8 With Softfocus Lens is a relatively small, light and inexpensive 135mm lens.
The unusual feature of this lens is its softfocus capability. The 135 L has a ring that allows continuous soft focus settings ranging from locked at 0 (none) to 2 with detents at settings 1 and 2.
Set at 0 (no effect), the 135 softfocus lens is somewhat soft open (f/2.8) and, like many other lenses, becomes sharper as it is stopped down. Corner sharpness trails the center of the frame by a stop or more. So this is a somewhat-sharp soft-focus lens? As Canon carefully denotes this lens as being "With Softfocus", a soft focus setting of 0 allows this lens to function like a standard 135mm lens.
Turning the softfocus ring past 0 dials in spherical aberration that produces a dreamy glow. The amount of effect is determined in part by the aperture and softfocus settings - and can easily be overdone. At f/2.8, a softfocus setting above 1 will probably be too strong for most tastes. Below f/4, a softfocus setting of 2 will likely be too strong for most people. Like many other aspects of photography, mastering this 135mm lens' soft focus effect takes time. Be patient and experiment with it. The ISO 12233 Resolution Chart sample crops for this lens include softfocus 1 and 2 examples.
Digital SLRs and Photoshop have negatively affected the demand for this lens as Photoshop can now be used to create a somewhat similar (maybe not exactly the same) effect during post-processing. But, effects post-processing takes time to learn AND time to do - the Canon EF 135mm f/2.8 With Softfocus Lens completes the task during the shot.
The Canon EF 135mm f/2.8 With Softfocus Lens is directly comparable to the Canon EF 135mm f/2.0 L USM Lens in focal length. But, they have many differences.
The 135 SF is smaller (2.7" x 3.9" / 69.2mm x 98.4mm - DxL), lighter (about 1/2 as much - 13.8 oz / 390g), less expensive (about 1/3 as much) and takes a smaller diameter (less expensive) 52mm filter. And of course, the 135 L does not have softfocus.
Although it does include a metal mount, the 135 softfocus lens has a lower end build quality while the 135 L is a solidly built lens. Appearance does not help a lens take good pictures, but the 135 SF's looks reflect its 1987 introduction year (among the oldest Canon lenses still manufactured). The 135 L was introduced 9 years later (1996) and sports a far more modern design.
While the 135 L features a fast, accurate and silent USM (Ultrasonic Motor), the 135 softfocus lens uses older AFD (Arc Form Drive) technology. This AFD implementation is not loud or slow focusing for a non-USM lens, but not as fast or quiet as the more-modern USM lenses - and it does not provide FTM (Full Time Manual) focusing. The 135 SF's manual focus ring is small, does not turn smoothly (the gears engaging inside can be felt) and has play in it. The 135 SF's MF (Manual Focus) switch feels cheap and also does not work smoothly. Both lenses focus internally (do not change size) and have non-rotating front elements. The 135 SF autofocuses even in softfocus mode. The 135 SF lens also proved to be difficult to get accurate focus with. While it nailed autofocus on most of my close portrait shots, other subjects proved to be difficult for it.
The Canon EF 135mm f/2.8 With Softfocus Lens is not the sharpest lens - it is certainly not up to the extraordinary sharpness of the 135 L.
Both lenses exhibited slight light fall-off wide open on a full frame body (of course wide open is 1 stop wider on the 135 L). This issue is not unusual and quickly cleared up for both lenses when stopped down slightly. The 135 L has minor pincushion distortion while the 135 SF has moderate pincushion distortion (strong for a prime lens).
The 135 softfocus lens has a 6-bladed aperture vs. the 8-blade aperture on the 135 L. Six blade non-round apertures will generally produce 6-sided out of focus highlights when stopped down.
CA (Chromatic Aberration) is relatively high on the 135 softfocus lens compared to the 135 L.
Color and contrast are a little better on the 135 L as well. That said, the Canon EF 135mm f/2.8 With Softfocus Lens is not bad in these categories. Neither lens has a problem with flare.
Lenses in the 135mm focal length range generally make good portrait lenses, and people make one of the best subjects for the 135 softfocus lens. Full frame body users will find head/shoulder portraits to be the tightest possible without cropping as the 135 SF has a relatively long 4.3' (1.3m) minimum focusing distance for a low .12x magnification. Extension tubes will take the maximum magnification to .22x and .33x for 12mm and 25mm tubes respectively. The SF lens is not compatible with Canon's extenders (the L lens is). The 135 L will allow tighter portraits with its 3' (.9m) minimum focusing distance (.19x magnification). When used on a 1.3x or 1.6x FOVCF body, the 135 softfocus lens will allow tighter head shot type portraits - but will also require a lot of subject distance for less-tight portraits.
People are one of my favorite softfocus subjects. The softfocus effect smooths skin and gives a dreamy look. However, my personal preference is for a short DOF (Depth of Field) background blur over the softfocus effect. A tight 135mm portrait shot at f/2.8 can create this effect very nicely as well.
Landscape photography is another use for the 135 softfocus lens. A fixed focal length lens does not offer the flexibility of a zoom, but the 135 SF can get the shot at this focal length range. On a 1.6x FOVCF body (or cropped full frame body image), flowers can make a nice softfocus subject.
The 135 SF does not come with a lens pouch or the optional ET-65 III lens hood.
The Canon EF 135mm f/2.8 With Softfocus Lens' dreamy soft focus capability invites creativity. If you want softfocus capability in a 135mm lens, the 135 softfocus lens is your only choice. If you need a relatively fast aperture in a 135mm lens and cannot afford to spend more than the Canon EF 135mm f/2.8 With Softfocus Lens' price tag, this lens is for you - it is a good value. Otherwise, I recommend the Canon EF 135mm f/2.0 L USM Lens or one of my other recommended portrait lenses over the 135 SF.