I had a dilemma at one point when I considered the following lenses:
Canon EF 24-70 f/2.8 L USM ($1200)
Sigma 24-70 EX DG MACRO ($600)
My research showed time and again that you get what you pay for and though it has a nice price tag, the Sigma was inferior to the Canon in both build and image quality.
However, I didn’t have $1200 on me at the time. Also, I knew that my 20D offered a 1.6x FOV crop factor which would push the focal length past walkaround and into portrait. Not a bad thing, but also not nearly wide enough for what I would want the lens I’d buy to facilitate. A change in options was needed.
17mm seemed appropriate as that would become near 24mm on my 20D. Therefore, I considered the following:
Canon EF 17-40 f/4 L USM ($700)
Canon EF-S 17-55 f/2.8 IS USM ($1000)
Sigma 17-70 f/2.8-4.5 DC MACRO ($590)
Again, my research nixed the Sigma as being inferior to either Canon lens. So it was down to the two Canons.
Do I need IS for anything?
No, I shoot mostly bright outdoors, studio strobe lit and low-light sports, each of which could not use IS.
That f/2.8 sounds pretty good, though.
Yeah, but it’s an EF-S mount and my next camera will either be a 5D or a 1-series, neither of which utilize EF-S and I don’t want to invest in a technology that I won’t be using during the next ten years. My 20D’s shutter will probably last another two years and I expect to replace it before then with another body.
Besides, the EF-S is still a consumer lens and suffers from the plastic build and an image quality that certainly is not as good as the L lens I’m also looking it. Plus, it’s more expensive because of the wider aperture and IS function.
I’m thinking I’d get more mileage out of the 17-40. It’s better built, has superior image quality, is durable, lets in enough light to hand hold in an ambient-lit room at ISO 800 and it’ll do just fine with certain styles of portraiture at the short end. Plus, it’s pretty cheap for a pro lens and very much within my price range.
So, I went with the 17-40 as my general purpose lens and have been so impressed that I’ve decided to never buy another consumer general purpose lens. Ever. Never ever.
Does this mean I won’t buy a sweet little fisheye lens from a Russian manufacturer?
Not at all. In fact, I already own one.
What about a LensBaby?
Are you kidding? Those things are super sweet and I want one!
But, these a specialty lenses, not general purpose lenses. General purpose lenses don’t leave the camera bag and sometimes don’t dismount the camera for days on end. Therefore my general purpose lenses are all Canon L-series. They’re simply better lenses, and that’s it.
However, although you do get what you pay for, there’s nothing wrong with living within your means and buying what you can afford. It’s why I went with the 17-40 rather than the 24-70, ultimately. It’s also the same process that led me to decide on the 70-200 f/2.8 rather than the more expensive, IS-enabled younger brother.
Sigma is pretty darn good and though not as great as Canon, still sees a lot of professional use. So if I didn’t need to worry about image quality (because I make giant prints) I’d go with the Sigma and save some beans, definitely. Then I’d go to Red Lobster with the money I saved…