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Special thanks to Markus Stamm for providing this lens!
The Canon EF 135mm f/2.8 SF is an unusual lens. It´s the only soft-focus (SF)
lens in the line-up. The position of an aspherical element can be altered
by the user causing a varying degree of spherical aberrations or in other
words a dreamy soft-focus effect. Using its default setting the lens can
also be used as a normal tele photo lens so SF is a strictly optional
feature. The lens was first released back in late 1987 so it´s one of the
oldest designs for the system.
As usual we´ll have a look how this lens performs on an APS-C DSLR
(EOS 350D/Digital RebelXT) - here the field-of-view is equivalent to
216mm on full-format cameras.
The optical design of the lens is made of 7 elements in 6 groups including
one molded aspherical element - quite unusual for a tele lens.
The min. focus distance is 1.3m, quite long thus resulting in a rather
unexciting max. object magnification of 1:8.3. The aperture mechanism features
6 aperture blades. The max. aperture of f/2.8 is relatively conservative
so the lens is quite compact (69x98mm) and light-weight (390g).
The filter size is just 52mm.
The EF 135mm f/2.8 SF is the longest non-L tele lens so its construction
quality remains quite conventional based on good quality plastics.
The focus ring is typical for Canon lenses that that design era - reads:
it is small. On the positive side it doesn't feel quite as scratchy as
similar implementations (of that time). The size of the lens remains
constant regardless of the chosen focus setting.
As mentioned above the lens
comes with a soft-focus option. Using a switch in conjunction with a
dedicated control ring you can set the soft-focus effect in three discrete
- "0" - no soft-focus (behaves like a normal tele photo lens)
- "1" - slight soft-focus effect
- "2" - strong soft-focus effect
The soft-focus generates some soft halos at contrast edges thus
generating a dreamy effect which feels a little dated to me but
your mileage may vary here.
The lens features a conventional AF micro-motor so things are a little
on the noisy side here. However, the AF speed is very fine which surely
also originates in the rather limited focusing range (1.3m to ∞).