I am thrilled with my recent 50D purchase too. I have had it about three weeks and upgraded from my 30D.
Everything in moderation...compromise...best of both worlds...neither fish nor fowl...have your cake and eat it too...balanced...the 50D is a really nice pro-amateur camera.
I have also had my 50D for a little while now, and am also very happy with it. I, too, shoot mostly at the "long end" of things, with my 100-400 being my most-used lens, mostly for wildlife, so an APS-C sensor makes sense for me.
I did have the opportunity, over Christmas, to play a bit with my 50D (about 1000 shutter clicks, now, compared with 14,000-odd on my 30D). I observed a few things and so did a few pixel-peeping exercises to compare my 30D with my father's 40D and my new 50D in some side-by-side comparisons (but not in any way a rigourous set of comparitive tests).
The first thing I verified, to my own satisfaction, was that the additional resolution of the 50D is really only available for use with the best of my lenses. When shooting with, say, my 35mm f2 lens at a range of apertures, with a range of subjects etc. I found all the cameras produced essentially the same useable image quality. Using one of my 3 "good enough" lenses (17-55f2.8IS, 100-400L or 100mm macro), however, provided substantially more detail with the 50D. The 30D and 40D were, to my eye, pretty close together in the useable IQ stakes, while with the right shot and the right lens the 50D could do substantially better, at least while pixel-peeping on-screen at 100%.
The second thing I more-or-less verified was that one of the things (but far from the only thing) that accounts for this is precision of focus. Taking repeated shots of the same subject with the same framing, changing focus between shots, showed far more variability with the 50D (when viewing on-screen at 100%) than with the 30D and 40D. This was not
because of any particular problem with AF on the 50D as such (as near as I could tell) but simply that the sensor on the 50D has sufficient resolution to actually register very small differences in focus and make them apparent when pixel-peeping the results. This can, of course, be masked by stopping down to increase DOF and varies with choice of subject, subject distance etc. But I convinced myself that for many subjects the 50D will show minor variations in focus that will go unseen on the 30D and 40D.
The third thing I verified is that the difference is real enough to be seen in 13"x19" prints if the shot was from the right lens, taken while focused and stabilised well then printed on media that can show the advantage. I printed two photos, one of a rainbow lorikeet (a very bright parrot) taken with my 100-400 and another landscape/cityscape taken with my 17-55. Comparing with similar (but not the same) photos taken with the same lenses on my 30D showed no particular advantage to the 50D prints when printed on Canon Photo Paper Plus at 13"x19", even when examining the prints closely. Printing on Crane Silver Rag or Harman FB AL gloss, however, showed a small but clear advantage to the 50D prints that was visible at "normal viewing distance" and reasonably obvious when examining the prints closely. A smaller advantage to the 50D showed when printing on Hahnemuehle Photo Rag with a 10"x16" image area (a size I often use). I can only assume that this advantage would show more clearly if printing larger prints (I can't, at home at least). I also verified that there's no real observable difference in print quality between the 30D and 50D when printing at A4/letter sizes or smaller.
I'll also note that the 50D has a number of usability and convenience upgrades over my 30D, but not so much over the 40D. I like, and make much use of, the additional dedicated button for engaging the AF separately from exposure/shutter release. I very much appreciate the dust-shaker in the AA filter (aka "sensor cleaning"). I like
having the ISO setting on full-time display. I really like the custom settings I can set up then access via the mode dial (though I'd prefer the 3 settings of the 40D; and give up the new "CA" mode I'll never use on my 50D). I'd no doubt appreciate live view, if I ever used it (which I don't). I presume the 50D's enhancements there are valuable for those who do use live view. I like the ability to work RAW files "harder" with 14-bit recording. I like the improvements made to AF. With the 50D, however, I'm somewhat less keen on the larger file sizes (unavoidable though they are if I want the resolution) and apparently higher battery drain (not that an extra spare battery is that big a deal).
This has led me to a number of conclusions:
- Unless using one of my better lenses, there's not much point preferring my 50D over my 30D, and the same goes for the 40D.
- The 40D is pretty much as good as the 50D (and even has some minor advantages) if you're not planning on making large prints, investing in lenses good enough to take advantage of the 50D sensor or have no real need to for the 50D's improvements to live view.
- Even with good lenses, you won't get the advantage of the 50D's resolution unless you also attend, carefully, to camera movement, precise focus and DOF management and a range of other minor sins that go mostly unnoticed on the 30D or 40D.
- So I'll continue to use my 30D as my primary walk-around camera (mostly with either a small 35mm or 50mm prime plus a spare lens) and reserve my 50D for "special photographic" occasions.
- And I'll recommend, when asked, that people seriously consider a 40D (or one of the more entry-level models) instead of a 50D if they don't plan on large prints or to purchase better and more expensive lenses.
The other thing much of this tells me is that perhaps we're getting to the end of megapixelage: why keep expanding pixel density if lenses, AF systems etc. start not being up to the job of acutally using the additional resolution?