In this week's video tutorial you will learn about the various benefits of processing your RAW files in an editing program. Paired with the advantages of shooting in manual mode, this important step...
The Canon EF-S 10-22mm f/3.5-4.5 USM is Canon's widest zoom lens (in fact
widest lens of any type) for the Canon 1.6x DSLRs which accept EF-S mount lenses,
i.e. the Canon Digital Rebel, Canon Digital Rebel XT and Canon EOS 20D.
EF-S lenses have a shorter back focus distance (i.e. the rear element is
closer to the image plane) then EF series lenses. This, in theory, permits higher
lens performance with very short focal length lenses - and 10-22mm counts as
"very short"! They have a reduced size image circle to match the 1.6x APS-C
format sensors and a modified lens mount which prevents them being mounted on
full frame camera. If they were mounted on a full frame camera, not only would
they not cover the frame, but the SLR mirror would hit the back of the lens.
Though the EF-S 10-22/3.5-4.5 USM isn't an "L" series lens, it does have
similar optical constuction to EF "L" series lenses. For example the EF 17-40/4L
uses 3 aspheric elements and one SD element (SD elements are "super low
dispersion" glass, which is similar to fluorite in optical properties). The EF-S
10-22mm f/3.5-4.5 USM also uses 3 aspheric elements and one SD element. It's
evident from this (and the price of the lens), that this is no "low end,
consumer" type lens. The optical design and mechanical construction of the lens
(which uses a ring type USM motor and has full time manual focus) are both high
quality. Some have suggested that if it hadn't been an EF-S lens, it might have
received the "L" designation, but since it won't fit on a pro level DSLR (EOS 1D
series), Canon didn't feel that could give it a "professional" L designation.
I've no idea if this is true, but it could be!
Optical Design of the Canon EF-S 10-22/3.5-4.5 USM
Green elements are aspheric, yellow element is SD glass
The zoom range is 2.2x, which is pretty good for a superwide zoom. There are
some 3rd party superwide zooms, but they are limited to 2x or less (10-22, 11-18,
12-24). In 35mm full frame equivalent terms the EF-S 10-22mm f/3.5-4.5 USM has
the same field of view as a 16-35mm lens on a full frame camera. This covers 16mm
as well as the standard prime focal lengths of 20, 24, 28 and 35mm. The
images below give you a feel for the difference between the two ends of the zoom
As I mentioned earlier, the Canon EF-S 10-22/3.5-4.5 USM has a
ring USM motor and full time manual focus. The lens does not change length when
zoomed, although it's not really an internal zoom lens. In fact the front element
moves inside a fixed outer barrel. The filter ring does not rotate on focusing or
zooming, making the use of a polarizer more convenient. One note of caution with
respect to polarizers though.
I found that a standard thickness polarizer (in fact a Tiffen
77mm PL-C circular polarizer) caused a small amount of corner vignetteing at the
10mm setting. At 11mm all was OK and at 10mm with a standard B+W warning filter
all was OK. So if you really want to use a polarizer at 10mm and you don't want
to have to crop or retouch the corners of the image, a thin polarizer seems to be
required. Obviously stacking filters will give you problems at the wide end of
the zoom - but you probably shouldn't be stacking filters anyway!
Focus is fast and silent. I measured that it took 300ms (0.3s) to
focus from infinity to its closest focus distance (9.5")
Full specifications of the Canon EF-S 10-22/3.5-4.5 USM are given
in the table below:
Canon EF-S 10-22mm f/3.4-4.5 USM Specifications
Lens Construction (groups)
Lens Construction (elements)
13 [3 aspheric elements - 1 Super UD
No. of Diaphragm Blades
22-27 (1/3-stop increments 22-29)
Closest Focusing Distance
0.24m [9.5"] at all focal lengths
0.17x at 22mm setting
77mm (thin polarizer required for 10mm
Maximum Diameter x Length
83.5mm x 89.8mm [3.3" x 3.5"]
Distortion was low at all focal lengths. There is some barrel
distortion at 10mm, but considering the wide angle, it's very low. At 22mm
distortion isn't noticable.
Vignetting without a filter was also low at all apertures and
focal lengths, with no real noticable darkening of the image corners. I'm sure
it's there and it's measurable (all lenses, especially wide angle lenses, show
some vignetting), but in normal use it's not noticable.
Below are full frame shots taken at 10 and 22mm, with areas in
red expaned into 100% crops below
Below are the 100% crops taken form the very top left corner of the above
images. The scales are in pixels to show you that these really are the extreme
corner of the image
At 10mm you can see some softness wide open and some chromatic
aberration. Stopping down sharpens the image but CA is unaffected (as would be
expected). Remember though that these are 100% crops, and on a typical monitor
represent sections from something like a 36" x24" image in the very corner. With
that being taken into consideration and by comparison with other lenses, I don't
think the performance at 10mm is at all bad, in fact it's surprisingly good for a
fast lens of such short focal length.
At 22mm things are sharp wide open and there is no visible
chromatic aberration. Very good performance.
Below are 100% crops taken from near the center of the image
It's evident that shapness is excellent wide open and changes
little with stopping down. Excellent performance at both 10mm and 22mm.
The Canon EF-S 10-22/3.5-4.5 is a very good lens. There is a little corner
softness wide open at 10mm, but overall the image quality is excellent. Those who
claim that this lens shows "L" quality performance may not be wrong. It is
$150-$200 more than the 3rd party competitors, but it does have a wider zoom
range than any of then, plus it has a silent, fast, USM ring motor with full time
manual focus. For many users these advantages will outweight the higher cost of
the Canon lens.
It is an EF-S lens, and so isn't usuable on full frame or 1.3x multiplier
sensor cameras. That may put some people off, but in reality I think the vast
majority of Canon EOS DSLR owners won't be moving to full frame in the next 3
years unless they have $3000+ to spend on a 5D body. Canon will likely keep the
Digital Rebel series with a 1.6x EF-S compatible sensor as long as the line
lasts, and it's very unlikley indeed that we will see a mid-range DSLR with a
full frame sensor priced under $1500 before 2009-2010, if then. So EF-S lenses do
make sense for many Canon DSLR owners. If they ever do go full frame, I'm sure
there will still be a thriving market for used EF-S lenses from owners of EF-S
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