Like most first-time DSLR owners, last year when I bought a Canon Rebel XSi, I started out with the kit lens (18-55mm f3.5-5.6 IS). This particular lens is pretty good as far as kit lenses are concerned. It’s reasonably sharp if you stop down the aperture a bit, and the image stabilization (IS) helps in low-light situations, but one drawback is the relatively short zoom range. 18-55mm (equivalent to around a 3x zoom on a P&S camera) will be okay for most short-range situations and landscape photography, but if you want to take photos from a distance (during nature or sports photography for example), then you really need a deeper zoom. I decided it was time to buy a medium zoom lens around 200mm (10-12x zoom). These are also called standard telephoto lenses, as opposed to the super-telephoto (300mm-800mm) lenses that are often much more expensive.

When shopping for a lens like this, it’s easy to quickly become overwhelmed by the dizzying array of choices available. I narrowed my requirements a bit to help make the decision. I wanted the lens to grow with my photography. Lenses last a long time, so it’s usually a good idea to buy quality lenses that you will be happy with in the long term. I also wanted a lens with a relatively wide aperture so I could get quick enough frame rates for full-zoom images. (Typically, when taking photos, you want your shutter speed to be 1 divided by the focal length on your lens. So with a 200mm zoom, you will want your shutter to be at least 1/200th of a second or faster. This rule doesn’t mean you can’t get sharp photos with a slower shutter speed, it’s just a general guideline for taking sharp photos while hand-holding the camera.) My budget was flexible, but I was targeting somewhere around $500.

After narrowing my criteria, I was looking at 2 different lenses in my price range: the Canon 70-300mm f/4-5.6 IS and the Canon 70-200mm f/4L. The Canon 70-300mm goes for just over $500, and some of it’s finer points include built-in IS and an extended range to 300mm. The Canon 70-200mm is just over $600, and is a member of Canon’s professional L-series. L-series lenses are generally very sharp and built with metal exteriors making them more durable. It’s worthwhile to note that Canon makes 3 more 70-200mm L lenses, all of which are far outside of my budget: the f/4L IS ($1100), the f/2.8L ($1200), and the f/2.8L IS ($1700).

I also looked at 2 lenses just above my price range (the Tamron 70-200mm f/2.8 and the Sigma 70-200mm f/2.8). These lenses cost around $800, so they are more expensive than the f/4L, but they are also offer the wider f/2.8 aperture and cost a lot less than Canon’s f/2.8 model. I thought I would give them a chance to see if it would be worth spending an extra couple hundred dollars for the faster glass.

Image Quality

This is the most important consideration for me when purchasing a lens. If you’re going to spend a lot of money on a lens, you want it to be sharp…tack sharp. To my surprise, I stopped considering the Canon 70-300mm much quicker than I expected to. I came across a review comparing it to the Canon 70-200mm lens. About halfway down the page, they have a sample photo showing a 100% crop of the 2 lenses (as well as a less-expensive Canon 55-250mm IS lens). The 70-200mm is significantly sharper to my eyes, and right away I knew it would be worth it for me to pay the extra $100 for the 70-200mm lens. This kind of disappointed me, because the 70-300mm has IS, which can make a big difference when you aren’t using a tripod, but I decided that while I could learn to hold the camera steady, the 70-300mm lens could never learn to take sharper photos.

Between the three remaining 70-200mm lenses, image quality is a lot closer. It was a close call, but the Canon lens seemed just a little bit sharper to me when mounted on a tripod, but not so much sharper to disqualify the Tamron and the Sigma. The Tamron and Sigma lenses could both take photos at f/2.8, meaning they could take a picture at twice the shutter speed of the Canon. Faster shutter speeds = sharper photos when hand-holding the camera, so this one is a real tossup.

Weight

All of these longer zoom lenses have a fairly substantial weight, but the f/2.8 lenses are significantly heavier. The 70-300mm and the Canon 70-200mm weigh in at around 1.5 lbs, whereas both f/2.8 lenses weigh around twice as much. It doesn’t sound like a lot, but it makes a difference in comfort when you are shooting without a tripod. The heavier lenses were fine for a few quick shots, but after holding them for a few minutes, it started to be a strain and the extra weight made them more difficult to hold steady. Also, it’s nice to have a lighter lens when traveling, and the f/2.8 lenses really made me question if I would want to carry them along on longer trips. The best lens is the one you’ll use, so here the lighter lenses came out ahead in my book.

Build Quality

Both the Sigma and the Canon have excellent build quality, while the Tamron lagged behind a little in this respect. It’s not that the Tamron lens is bad, just in the middle-of-the-road. The outside of the barrel is plastic, which just doesn’t feel as nice. Also, the Tamron lens doesn’t have full-time manual focusing like the others. You have to slide the focusing ring to switch to manual focus, which is easy to do, but full-time manual focusing on the other lenses is a lot nicer. The Sigma lens has a very nice smooth feel on the outside. It is something of a combination between felt and rubber. If Apple used the same exterior coating on laptops, I would be thrilled. On the flip side, it seemed like it might be the type of material that could get scuffed if you scratched it. The Canon lens has rubber grips for the focus and zoom rings, and the rest is metal. It feels very solid, but I imagine it might make the lens pretty cold when taking photos in the winter time.

Focusing

The deciding factor for me between the remaining 70-200mm lenses was the focusing speed and accuracy. The USM motor in the Canon is very quick to focus, and almost silent when focusing. The Tamron motor, on the other hand, is relatively noisy and I often waited for it to snap into focus. The Sigma is a quiet HSM focusing motor, but it still doesn’t feel like it focuses quite as quickly as the Canon. Since I would like to use the lens for some sports photography, where focusing speed is king, the Canon 70-200mm wins this one hands down.

Bringing it Together

In the end, I’m the happy owner of a Canon 70-200mm f/4L. I’ve had a few weeks to get out and take some nature photos with the lens (I’ve included some here), but I’m still getting used to it. I have found that it usually takes 3-6 months to get to know a lens, and this one has not been an exception. So far though, the image quality has been great, and I’ve been practicing holding stances and relaxing when taking photos, in order to keep the camera shake to a minimum. I think this lens will be in my camera bag for a very long time.