David vs. Goliath - can the little guy win?
by Bob Atkins
The test was done by Rob Lytle. He took these shots using an EOS 300D and then
burned these images onto a CD and mailed it to me and I (Bob Atkins) did the
analysis.
Technical Details - All shots were taken with the camera
mounted on a sturdy tripod using a remote cable. The camera, tripod, and aiming
of the camera were not changed at any time during the test - only the lenses were
swapped out. The camera's ISO was set at 100 and exposure mode to aperture
preferred so the exposures could be made at the specified settings. The RAW files
were converted to 18MB TIFFs using Canon's File Viewer Utility supplied with the
camera and white balance was set to "Cloudy." Brightness and contrast adjustments
were made in PaintShop Pro 8 to a standard level for all exposures. The same,
minimal level of Unsharp Mask was applied to all images.
First let's just take a look at a shot taken wide open at 18mm with the EF-S
18-55/3.5-5.6 lens. We can't compare it with the 24-70/2.8L of course since that
lens doesn't have 18mm. We can definately say that at 18mm, the EFS lens wins
every time!
It's actually not bad, but it does show some problems. There is vignetting as
shown most obviously by the darker sky in the top left corner, but if you look at
the other three corners you can see darkening too. This is real since the same
shot taken at f22 shows pretty uniform illumination. Image quality is OK in the
center but a bit soft at the edges. This will be more obvious in the following
comparisons with the Canon EF 24-70mm f/2.8L at 24mm, 35mm and 55mm. First let's
look at the edges at 24mm. Note that all the image crops follwing are taken at
200%, which is to say they are 2x "life size".
Not much doubt here about which lens produces the better image.
The EFS lens shows much lower contrast and resolution, even though it's working
1/2 stop slower than the "L" lens.
Below are two shots comparing the two lenses set to 35mm focal
length. One shows the edge quality wide open and the other shows the center
quality at f8
Looking at the edge image, even though the EFS lens is working at
1 1/3 stop slower, it's image quality is still inferior to the "L" lens. Contrast
and resolution are down. At f8 and in the center of the image there isn't a lot
of difference. Again the "L" lens shows a little more contrast, but both lenses
exhibit good image quality. The two images below show the edge quality at the
same setting.
As you can see, even though the images at 35mm, f8 are quite
similar in the center, the EFS lens is again down in performance showing the
previously observed loss of contrast and resolution.
Moving on to 55mm, the two images below show the edge quality of
the images obtained at f8. It;s clear in this case that the EFS lens shows higher
levels of chromatic aberration - as evidenced by the yellow/purple fringing on
the lamp post.
So what if we stop all the way down to f22. Will that make the
lenses more equal. The images below show that the answer is "no". You can see
that both edge and center contrast is lower with the EFS lens, and the edge is
also lower in resolution.
Are things any better wide open, where the EFS lens will be at
f5.6 and the "L" lens at f2.8? Can the f5.6 quality beat the f2.8 quality - or at
least equal it? Again the answer is "no". As you can see from the two images
below, the EFS lens shows lower contrast and resolution.
So the "L" lens seems to win at all apertures in all respects -
this should not come as much of a surprise. The EFS lens costs $100, the "L" lens
costs $1200. If the "L" lens didn't beat the EFS, Canon would have some
explaining to do!
One more thing to compare is color balance. I noticed that the
EFS lens seems to give slightly warmer images. The 4 images below illustrate that
I think. Each one has the RGB value of the whole image averaged. If you look at
the ratio of red to blue in each case, you'll see the EFS lens has relatively
more red, resulting in a slightly warmer (red/yellow) tone. It's hard to say
which is more "accurate" and both are easily corrected, so I wouldn't say this is
a significant difference - certainly not when used with a digital body. Since you
can't use the EFS lens on anything but a digital body (indeed at the moment you
can't use it on anything except an EOS 300D unless you take a hacksaw to it), any
comments about color balance on slide film are moot.
Conclusions
Despite the fact that the "L" lens won in every comparison, I'm
being pretty picky and I'm looking hard for faults. The Canon EF-S 18-55mm
f/3.5-5.6 actually looks like a pretty decent lens for casual use, and at $100
it's probably a bargain. It seems to suffer from the same defects that I've seen
in similar low end, plastic mount, canon lenses (22-55/4-5.6 and 28-90/4-5.6,
both of which sell for around $100 also). Contrast tends to be low, especially
wide open, and edges tend to be soft. If you're intending to shoot landscapes and
make full frame 13x19 prints, you're probably going to be disappointed. On the
other hand if you're printing 4x6 prints you'll probably be delighted. At 8x12 it
probably depends on how picky you are.
If I was buying an EOS 300D, I'd certainly fork over the extra
$100 for the Canon EF-S 18-55/3.5-5.6 unless I already owned a lens covering this
range. The only competitors might be the Sigma 12-24/4.5-5.6 (around $650) and
the Sigma 15-30/3.5-5.6 (around $580). Both are wider and thus arguable more
useful, but both are about 6x more expensive. The Canon 17-40/4L USM is also a
competitor, but it sells for about $700.
Remember of course that though these sound like really wide
lenses, by full frame 35mm standards thet aren't particularly wide, due to the
smaller sensor of the 300D (which results in the 1.6x "focal length multiplier"
effect. An 18-55/3.5-5.6 on the 300D gives you about the same coverage as a 28-90
on a film body, and it's not a coincidence that the standard lens supplied with
the film based Rebel bodies is a low cost 28-90/4-5.6 zoom!
| Focal Length |
12 |
13 |
14 |
15 |
16 |
17 |
18 |
19 |
20 |
| 35mm equiv. |
19.2 |
20.8 |
22.4 |
24 |
25.6 |
27.2 |
28.8 |
30.4 |
32 |
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All images ©2004
Rob Lyle, text ©2004
Bob Atkins and
Rob Lytle
