The canon 50d is a solid camera, I use one. I don't use zooms often so I can't comment on the 18-200mm, mostly for sharpness I use primes, a 35mm and a 50mm macro. I do have the 28-135mm and after sending it to Canon for repair, it is quite sharp. I have also used the Canon T2i, it is pretty good! As far as I can see with the T2i, because of the sensor size diffraction becomes an issue quicker than with my 50d. Cheers!
It's the range of your zoom lens that I think reduces the quality. My main lens is a 24-105mm lens, but it's an "L" lens that I use on the 40D (predecessor of the 50D). In combination with plenty of light it is a super lens.
But then again, it all depends on your budget. It might be good to start of with. I started with a cheep lens and learned how to use a DSLR. As I made some money with stock I traded in my lens for a better one, etc.
The 50D is definitely a great camera, and perfect for stock.
I got EF-S 18-200mm f/3.5-5.6IS lens when I bought my 7D, when I received the lens, I thought it was a piece of crap because of its plastic build. But I was quickly surprised by the result when I was toying with it. When used properly, this lens can produce great sharpness. The IS is also great for hand held shots down to 1/20, again when used properly.
Macro | Canon 17-40mm/f4 L | Tokina 11-16mm/f2.8...
Quoted Message: i wanna buy a camera ! anny suggestions guys ? my budget is about 2000$
With that budget I suggest that you look at 7D or 550D. Glass is what matters more than weather seals if you are using your camera for stock.
Also, try not to buy kit lenses with your camera. Buy some L quality lenses with remaining money.
What I have is 550D, 50mm F1.8II, 70-200 F4 L, Helios 44 (Russian manual 58mm f2.8 glass), Mir 1V (Russian manual 37mm f2.8 glass)... Trying to find something near to 24mm and that will do... It works excellent, makes nice photos and great quality full HD videos!
For full frame you'd need budget of around $3000 - $4000 minimum!
With recent development of Canon 120MP APS-H sensor it looks like Canon brand will be winning for some time from now...