And as I mentioned before, at the entry level there is not so much
to choose in terms of image quality, most are 8-10MP camera bodies,
and for instance the Sigma 50-500 is available in most mounts.
The in-body stabilization of the Sony or Pentax for instance will
convert this into a stabilized lens. It then comes down to a variety of
other factors for which people need to decide for themselves what
is important, eg
How good is the viewfinder? People seem to like the Pentax on this
score; the Canons could be better, esp the Rebel series (350D/400D)
which have a dark viewfinder with low magnification (around .84 IIRC)
How fast is the focus? Canon USM and Nikon AFS lenses are very fast
to focus. Sigma HSM are also good; I don't recall if the Sigma 50-500
is an HSM lens.
How accurate is the focus? How is the low light capability?
How well does servo tracking keep up with a moving target?
Canon's is OK, but I find it frustrating at times (probably flaws
in my technique as much as the camera).
What is the frame rate? The Canon 30D is 5fps, 400D is 3fps;
most others are 3fps or less. That can be frustrating if the action
is fast or you want the right wing position on a flyer, and the
burst rate is too slow.
How big is the buffer? Even more frustrating than the last one
is waiting for the last burst to clear the buffer while something
good is happening and you can't capture it.
So those are some of the issues. I've mentioned my preference
in an earlier post, but the recent entries from other manufacturers
have made the entry level market much more competitive than
it was a couple of years ago. I still think Canon has the edge,
but not by a lot, and it is definitely worth giving the others
a look. If however one is potentially interested in
upgrading to high end gear, Canon is definitely the way to go.
--
emil
--
http://theory.uchicago.edu/~ejm/pix/20d/