(continued over from EF 70-200 f/2.8L vs 70-200L f/4. Part 1)
Beware of fogging with the f/2.8L zoom.
At the risk of getting into trouble with the powers that be, I must confess
that through the years, I've noticed that several samples of the f/2.8L zoom
(including mine) begin "fogging" in certain central lens elements. This
fogging looks like a very fine patch of light cream coloured mist which can
be detected if you hold your lens up to the light at a certain angle or
shine a torch through the lens. It is different from fungus. Some of these
lenses are already fogged up out of the factory while others seem to develop
it through the years. I have yet to see any f/4L zooms with such fogged-up
elements but then again, it's a relatively new lens.
I have a nagging suspicion that certain elements in the f/2.8L zoom tend to
either discolour or fog through time. It certainly does not affect all
units, but I've seen a few with this problem. I've seen some samples which
had fine bubbles in certain elements. Canon may tell you that these symptoms
will not degrade optical quality and I tend to agree if it's only tiny
bubbles and not too many of them. However, depending on its severity, fogged
lens elements WILL aggravate flare and will reduce image contrast when
photographing contre-jour scenes.Front-lit subjects are usually not affected
though. Canon will replace fogged lens elements at a price or perhaps FOC if
it's under warranty, but there is always a risk that the optical alignment
of the zoom lens may be affected once it is dismantled and a new element is
inserted.
I have compared two similar L lenses and the one with fogged elements
exhibited lower contrast, noticeable even through the viewfinder. If you're
buying the f/2.8L zoom, check for lens fogging and quickly return it if your
unit has it. In contrast, I have yet to see an EF28-70 f/2.8L develop lens
fogging. I must also add that I have seen this phenomena in the EF17-35L and
EF135L f/2 lenses.
Please realise that my intention is not to start a panic or make you lose
confidence in Canon. I honestly believe that this fogging issue is certainly
more of an exception than the general rule...however, I have noticed it more
than once and it pays to be cautious.
_______________________________________
Bokeh
Besides resolution and contrast, more and more people are realising the
importance of "bokeh" or the quality of the out-of-focus zones. Lenses which
deliver a cleaner, smoother blurred-out background can give the impression
that the in-focus zone seems sharper and provide a more 3-dimensional look
to the subject. It is also less distracting.
Which lens has better bokeh?
Without a doubt - the f/2.8L wins hands down. Not only does it have a larger
aperture which makes it capable of rendering that extra bit of additional
background blur, the quality of the out-of-focus areas are more pleasing.
The bokeh is very smooth and clean, whereas the bokeh of the f/4L
(especially closed down)can appear rather smudged and distracting.
Now, let me stress that the quality of the background blur depends on the
background and its illumination. A flat field of evenly lit green grass will
be nicely blurred out with almost any lens. However a tangled bush with
brightly coloured flowers under harsh dappled lighting can be a nightmare
with lenses of poor bokeh. Honestly, the bokeh of the f/4L is not too bad,
certainly much better than that rendered by the EF100 macro f/2.8 USM which
I consider simply ghastly! However the f/2.8L zoom provides a quality of
background blur which is smoother and much more pleasing. If you're deciding
between either lens for portraiture and the quality of background blur is
important to you, may I suggest you seriously consider the f/2.8L. The f/4L
isn't too bad, but pay more attention to messy backgrounds should you use
it.
____________________________________
In the Field
If your technique is perfect, I dare say you'd be truly hard pressed to see
any difference in sharpness between these two L zooms. Honestly, they are
that close! However, in actual use, I was shocked to note that my handheld
shots from the f/2.8L zoom were consistently sharper and more crisp compared
to those from the f/4L. I was very surprised as my meticulous tests had
revealed both lenses to be extremely close in optical performance.
I soon discovered that I was getting poorer results from the f/4L zoom not
because it was a lousy lens, but simply because it was just too light and
did not balance well on my heavy Eos 1V. You need a certain amount of mass
to stabilise a tele lens and the 705gm f/4L zoom was just too light for
stable handholding. (Of course, your mileage will vary). The f/2.8L at 1.3kg
is slightly over the top and may prove a bit strenuous for long shoots, but
for me, it provides near perfect balance when coupled to the 1V. If you use
an Eos Elan 7/ 33 or Rebel series camera, the f/4L version may provide
better balance.
In order to maximise the capabilities of the f/4L, you need a tripod, but
herein lies the problem - the darn lens does not come with a tripod collar!
Try shooting vertical portraits with your heavy Eos 1V tilted over the axis
of the tripod ball head and you'll quickly understand my frustration. If you
want this lens - get the tripod collar or else don't don't be too quick to
dismiss its performance if you handhold it. Funny isn't it? You'd most
probably want this lens for its light weight and use it at times when you go
travelling or don't want the hassle of lugging a tripod. It is exactly
during such moments that you may find it difficult to maximise its optical
potential. Well, just try to keep it as steady as you can.
Both lenses can be used with either EF1.4x or EF2x converters. Optical
performance is still very good with the 1.4x and quite acceptable with the
2x. Stopping down will improve contrast and resolution. If you plan on using
converters, the f/2.8L will have an edge as you'll still be able to employ
45-point focusing (although Canon does not recommend it) versus single point
AF with the f/4L with 2x with the 1V or 3. AF slows down tremendously for
both lenses when attached to the 2X converter.
_________________________________
Which to buy?
The choice is yours. Optically, both lenses are close...very close. They are
of professional quality and in the right hands, will deliver impressive
results even when used wide open at all focal lenghts. Of course, closed
down a stop or two, these lenses reach their optimal optical performance. If
sharpness is all that matters to you - toss a coin - both will suffice.
If you need that f/2.8 aperture, the choice is clear. The f/2.8L is better
for low light photography and sports, balances better for hand-held
shooting, has better bokeh and a lovely tripod collar. It is also more
versatile with converters. Just avoid the occasional unit with fogged lens
elements, especially when buying used!
The f/4L zoom is useful for those who hardly have any need for f/2.8 and
simply desire a lightweight, relatively compact, high-performing optic. This
is the one to go hiking, cycling or trekking with. Long walks with the heavy
f/2.8L is a real pain and for those who still want to ramain standing and
take pictures upon conquering that freezing summit, the 70-200 f/4L is
Godsent. If you get this lens, do yourself a favour and purchase that
overpriced tripod collar. Life's much easier that way.
As for me, I finally sold off my f/4L and got the Leica VE 80-200 f/4 which
mates to my 1V via a custom-made adapter. I lose AF and it's only
stopped-down metering. But the lens delivers exquisite colour, contrast and
resolution, has good bokeh (although I still think the f/2.8L is better)and
is almost totally free from flare. Weighing in at 1kg, it also balances very
well with the 1V. It's a lens I use when I'm taking it slow, but when the
shooting gets fast and furious, out comes the f/2.8L. The only thing I
dislike about the f/2.8L is its size and excessive weight.
Which one is best for you? Only you can tell.
Warm regards,
Jonathan Kwok
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