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At 500mm, the image quality of the Sigma
get worse. It is still usable with some
post processing, but it get softer and it
has a visible chromatic aberration. If you
compare it with a photo taken at 400mm with
the Canon 100-400 (interpolated to match the
magnification of the 50-500), the Canon
shows a little more detail wide open, in
spite of the shorter focal length, while at
f/8 they are about the same.
Image Stabilization
comparison
I don't do often tests
of image stabilization because it is
difficult to make a scientific
comparison, but in this case I wanted to
do a test because my first impression
was not very positive. Even with
stabilization active, I did not see much
improvement, so I compared it with the
Canon 100-400. I have taken 10 handheld
photos with each lens at the test
subject shown above; I have used an
extremely slow shutter speed (1/10) at
400mm. I did not expect sharp photos at
this shutter speed, but I was curios too
see if the photos taken with the Sigma
had more or less motion blur. The
following images are 100% crops from the
10 photos.
The Canon 100-400 has a
more effective stabilization, as I
thought. Actually, the Canon 100-400 is
not that great in comparison with recent
lenses that have 4 stop IS, but the
Sigma has a really poor image
stabilization - I'd say it gives about 1
stop advantage, while the Canon is about
2 stops.
Samples and comments
These are some sample
photos taken with the Sigma 50-500 OS
HSM on Canon 7D, plus one photo taken
with the Canon 100-400, for comparison. You can download
either the untouched photo (JPEG
converted from RAW without any
additional post processing; minimum
contrast and saturation, no sharpening,
no AC, distortion or vignetting
correction) or the post processed
version. The untouched photo is a good
way to see the real image quality of the
lens, and the post processed versions
allow to see the final quality you can
get with good post processing
techniques.
The new Sigma 50-500 has
an image quality in line with its
predecessor: very good for a 10x zoom.
It is not super sharp wide open at
500mm, but for sure it is usable, and
overall I wouldn't hesitate to use it at
the widest aperture at every focal
length. The Canon 100-400 is a little
better at the long end, but overall both
lenses are capable of good image
quality. At 400 and 500mm, the Sigma has
some chromatic aberration, but you can
easily fix it with Photoshop.
Conclusions
The Sigma 50-500 OS is a nice update of
its predecessor; it has kept good image
quality (impressive for a 10x zoom!) and it
adds the very useful image stabilization,
even though it is not very effective: it
helps, but it does not come close to the
impressive 4 stop IS used on recent Canon
and Nikon lenses.
The 50-500 OS has only one big problem:
price. The old 50-500 was around $1000, the
new 50-500 OS costs $1600, a price that put
this lens in direct competition with the
Canon 100-400 IS. So, if you had to choose
between Canon 100-400 and Sigma 50-500 OS at
the same price, which one would you buy? I
think that the majority of people, me
included, would go for the Canon. There is
not an huge difference, but there are many
little things that overall makes the Canon a
better lens: slightly better image quality
at the long end, much faster push-pull
zooming, slightly faster AF, more effective
image stabilization, better built quality,
lighter weight and smaller size.
In conclusion, the 50-500 OS is a good
lens, but I would not buy it until the price
drops to more reasonable levels, as its
$1000 predecessor.
Do you have
comments or questions?
If you have comments or questions about
this article, feel free to ask in the
Juza
Nature Photography Discussion Forum!
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