[The glossary page may help with any unfamiliar terms.]
Everyone needs a wide angle lens. And usually you get a kit lens with your camera, which does wide angle, but at a good price. For instance, the Canon EF-S 18-55mm f/3.5-5.6 II (which comes with the Rebel XT/350D) is a pretty good lens. My used 350D didn't come with a lens, so I needed a wide-angle lens to complement the Canon 50mm f/1.8 II (a required lens for any Canon camera). Instead of buying a used Canon 18-55mm (which goes for $70+shipping on eBay if you can get a good deal) I decided to get a slightly better lens.
After doing my homework, I settled on the Tamron AF 19-35mm f/3.5-4.5. I found a number of good reviews on it. Not spectacular, but for a $100 lens (used, on eBay) it seemed like a worthy step up from the kit lens and a good complement for the 50 f/1.8. I used it, it worked for me, but the time came to upgrade.
My new lens (which came two weeks ago) is the Tamron SP AF 17-50mm f2.8 XR Di-II LD Asph IF [Amazon link] (geesh, what is wrong with these companies... why the crazy-long model names?). It has had some sterling reviews and it should -- it costs $440 new (used Tammy 17-50s are few and far between since they are so well-liked and only came out last year). As a new photographer, I'm sure you are wondering what makes the 17-50mm worth over four times as much as the 19-35mm, I know I was. So I've decided to do a short comparison of the two lenses (including visual aids!) before I sell the 19-35mm on eBay.
So, let's compare them by listing the advantages and disadvantages of each lens:
Tamron 19-35mm f/3.5-4.5:
- Much cheaper... Only ~$90+shipping for a lens on eBay.
- Lighter: 11.2oz (317g)
- Full frame coverage. Use it as a super-wide on a 35mm EOS camera.
- Includes petal-shaped hood.
- Cheaper construction, but still quite good. Metal mount, feels solid and well made, but there is more backlash in the autofocus and the end of the lens moves a little in relation to the base.
- Good sharpness, as long as you aren't wide open with it.
- Good color reproduction, if you adjust in software.
- Smaller zoom range -- you DO notice the missing range and it can be annoying to switch between the 19-35 and the 50mm f/1.8.
- Smaller aperture, especially if you take into consideration the need to stop it down a bit to get good sharpness.
- Larger 77mm filter size = more expensive filters.
- Slower autofocus.
- Smaller 67mm filter size = cheaper filters.
- Faster autofocus -- maybe 1.5x faster?
- Seems better built -- very little backlash in the autofocus, tight zoom, no play of the end of the lens in relation to the base.
- Large aperture, sharp even when wide open at f/2.8.
- Good sharpness through the whole range.
- Good color reproduction.
- Includes petal-shaped hood.
- Expensive... $380+shipping for gray-market, $430+shipping for warrantied lens.
- Noisy autofocus! Like angry bees.
- Heavier: 15.2oz (430g)... I really noticed the heft when I first got it, but don't notice any more.
- Only works for APS-C sensor cameras (smaller digital sensor, terminology is EF-S for Canon, Di-II for Tamron).
- More barrel distortion at 17mm than I would generally like.
Before we go further, let me present some real-world images from the lenses in question. These images were taken using the same camera settings as much as possible (manual mode on my 350D, tripod mounted using remote release, best quality JPEG, parameters "Parameter 1", cloudy color balance, 24mm focal length, f/4 (1/500s) and f/8 (1/125s)). A matrix of overall images is shown below (click to see a larger, but not full-size, version).
The main thing to notice here is the 19-35mm has some vignetting wide open (f/4 is wide open for 24mm focal length) and the 19-35mm makes slightly bluer images. Actually, one thing I noticed even before I got the 17-50mm was the 19-35mm seemed to lack 'punch' in the colors. I noticed it, but I couldn't really come up with hard facts until this test.
Turns out the 19-35mm attenuates the red (and blue, to a lesser degree) channels compared to the 17-50mm. The histograms at right (from Picasa) really demonstrate the problem. Noticeable, especially in a direct comparison, but easily fixed in a photo-editing program if you are aware of it. Or better yet, do a custom color balance before shooting and then don't worry about it. This may be the 'special coatings for digital cameras' they tout in the 17-50mm literature, since the 19-35mm is no longer made and was designed for film cameras.
This next comparison lets you see a 100% crop of the corner of the building in the middle-upper right of the frame. Click to see it at full resolution (blogger doesn't show the 100% crop version on the main page).
Many other sites have done more detailed tests of both of these lenses, so I've placed this here just to confirm my suspicion that the 19-35mm was soft wide open but gets quite sharp as you stop down. Maybe the 17-50mm is slightly sharper at f/8, but really only the 19-35mm at f/4 sticks out like a sore thumb with nasty softness and chromatic aberration.
And that's what you pay the extra $350 for: better performance at the wide-open end of the range and slightly better color balance. Worth it? Probably not when you are starting out on a short budget, maybe never if you only shoot outdoors.
For a general walk-around lens, you can't go wrong with the Tamron 17-50mm f/2.8. It is very sharp, even at a large f/2.8 aperture, and over the past few weeks, I haven't noticed any problems with my images (other than barrel distortion at the wide end). That's the key, you can use it without worrying about it.
On the other hand, if you are on a tight budget, go for the kit lens, the Canon EF-S 18-55mm f/3.5-5.6 II instead. If you have film camera too, then I recommend the Tamron 19-35mm since it has a better build quality and you'll get double-duty out of it. Otherwise, it is worth saving a little bit of money and getting the extra zoom range. Yes, with either of those lenses, you'll have to worry a bit more about shooting wide open and getting a decent shutter speed, but the $300+ you save on a wide-angle lens can be used to get an entry-level telephoto lens, a tripod, some flash equipment, an extension tube set, an extra battery, etc. Starting out on a short budget, you are much better off learning to use a wide variety of equipment than getting super-quality glass. That way, when you get some cash, you'll know how to use that cash most effectively.
Then, when it comes time to upgrade and you have the money, get the Tamron 17-50mm f/2.8. It is an excellent lens. And if you still want to upgrade after that, maybe the Canon EF-S 17-55mm f/2.8 IS USM is appropriate (or one of the Canon L series lenses).
Acquiring the Lenses:
Now that I know how to use the eBay widgets, I figured I'd save you some time and put up the searches. For the 19-35mm (for which eBay is pretty much the only option):
Obviously, the 17-50mm can be bought new at a lot of places, but Amazon ($430 at this time with free shipping) typically has one of the best prices. You can also find good deals on new and used ones on eBay (at best, maybe $10-20 less than Amazon, but make sure you consider shipping costs too -- mouse over to see them).