Wednesday, October 5, 2011

Camera Lenses 101: Going Long

The Sigma 100-300 DG HSM APO: an excellent telephoto lens.

After the standard walk-around lens (whether it be zoom or prime), the next optic most people look to when building a kit is the high-power telephoto lens. Whether they be zooms or primes, telephoto lenses greatly expand photographic applications thanks to their extra long reach. And, just like standard walk-around lenses, thanks to the high demand, the telephoto lens market is very crowded, and not always with good products, either.

Let's start with the telephoto zooms.

If you look in every manufacturer's lineup, you'll be sure to see one, if not more, telephoto zooms in the 70-300 f4-5.6 (or equivalent) range. Why so many lenses of this specification? Simple, they're cheap and easy to make, unfortunately, the results produced by such lenses are often in accordance to the price. However, like with the kit zooms, the quality (at least optics-wise) are starting to get better with the low-priced telephoto zooms as customers have been demanding better, and manufacturers are starting to offer products accordingly. Some of the new 70-300s are now getting stabilizers, sonic drive AF, weather sealing, or any combination. However, the more add-ons are attached, the higher the prices go, too.

The next class of telephoto zoom is the short, fast lens, typically a 70-200 f2.8 optic. The bread and butter of many working pros, such lenses are ideal for low-light conditions (provided they can deliver the goods wide open). Unfortunately (their fast aperture should have been a clue), such lenses are typically very expensive, with even the third party models running for around $750 new. When one adds a manufacturer nameplate, weather-sealing, sonic drive AF, and a stabilizer, the price can be pushed to nearly $2,500.

The other class of telephoto zoom is the extremely long model, with some lenses in this class reaching 500mm at the telephoto end. Essentially, these are big brothers of the 70-300s in that they are typically f4-5.6 (or even 6.3) in order to keep the size down. In terms of price, these range dramatically, starting at around $500 and nearing the $2,000 mark on high-end models. As with everything else, the addition of weather seals, sonic-drive AF, and stabilizers up the price dramatically. As a bit of advice, when buying such lenses, getting fast shutter speeds becomes increasingly important to prevent camera shake, which manifests itself at an ever quickening pace the longer the lens is.

Now, onto primes.

The first group of telephoto primes are the modern AF versions. More than any other class of lens, the price variances here is dramatic. Stating at around $600 for a 200ish f2.8 model, primes can go over the $10,000 mark with the 600+mm designs, especially those that add sonic AF and stabilization. The good news with telephoto primes is that they typically work well with teleconverters (at least the more modest 1.5x types). In short, getting, say, a 200 f2.8 and a 1.5x teleconverter is cheaper than buying a 300f4 and will typically produce results that are almost as good. This aside, being optimized for a single focal length, primes will almost produce better images wide open than zooms.

Next up for telephoto primes: the obscure brand optics. Typical prime manufacturer optics over 300mm are out of most people's price range. In contrast, many obscure manufacturers offer 400mm and up lenses for just a few hundred dollars, often about $300 at most. So, how do they do it? Answer: chop the AF, focus confirm, build quality, reasonable focal ratios and presto, sub $300, 400+mm lens. My advice? Skip these as even a cheap 70-300 is better by virtue of the AF alone!

The good news with telephotos is that, more so than with the other classes of lenses, price is a direct indicator of quality with the zooms as there really are very few hidden gems lurking in bargain-price category. Primes? Well, as long as they don't need some kind of adapter to attach to the camera (think those 500mm lenses priced at $300), they should be good, at least optically, too.

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