Alan Rockefeller said:

PatrickKn said:

If you don't put them through an image editor or decode them, then yes, they are. They can trace exactly what camera (serial number and all) the photo was taken with.

---

Oh really?

Here is an original, full size and completely unedited picture that came from my camera.  Please let me know what my cameras serial number is.

http://mushroomobserver.org/images/orig/212636.jpg

---

PatrickKn said:

According to my search, the serial number is 0470222664 and it was taken with a Canon EOS 60D.

---

koraks said:

Oh and btw, that lens suffers horribly from diffraction at 18mm and f/22. I'd recommend to shoot a scene like that at no smaller than ca. f/7.1 - it provides plenty of DoF and will result in a much sharper image.

---

koraks said:

Oh and btw, that lens suffers horribly from diffraction at 18mm and f/22. I'd recommend to shoot a scene like that at no smaller than ca. f/7.1 - it provides plenty of DoF and will result in a much sharper image.

---

Thanks. 

What does the focal length have to do with diffraction?

---

Well, in theory not much. Diffraction is mostly linked to the physical size of the aperture and the physical construction of the aperture. Thing is, though, that f/22 @ 18mm is a really tiny hole. In practice, this means that diffraction offsets any possible benefits of a larger depth of field anywhere upwards from f/5.6 or so in ultra wide angle lenses.

Quote:

With the more expensive lenses (L series) can I use smaller f-stops without diffraction?

---

Yes; that is to say, I see distinct differences between my cheaper EF-S (or comparable) lenses and my L-lenses (not that I have a whole arsenal ). Still, the same physics apply, and you'll find that even an EF-L 17-40 f/4 can get pretty soft upwards from f/8. The only thing that would really help is switching to a larger format; e.g. medium format photography. But I don't consider that a realistic option

The question of course is if you want to invest the $$$ for the extra stop of good performance of an L objective, not to mention if you're willing to haul the back-breaking weight of L lenses around all the time through a slippery and sweaty jungle. While the 18-200 you're using is evidently an optical compromise that many wannabe-professional photographer would scorn, I think it's a very realistic choice given the type of photography you do. The only thing superior, in my opinion, would be a 50/1.8 and a set of extension tubes for macro work But then again, I don't mind being stuck with one focal length.