Understanding Camera Lens Model Numbers

Most products these days appear to be named by--and for--robots. My television is a Sony KDL46EX600, for example, and I recently found myself shopping for a refrigerator that goes by the sexy name of GSCS3PGXSS. Jennifer Blue, from Australia, recently asked a great question about decoding lens names. The answer simply wouldn't fit in November's frequently asked questions, so I decided to unravel this mystery here.

The Mystery of Two Similar Lenses

Jennifer wrote with a quandary: Why are two seemingly similar lenses priced so differently? She had the opportunity to try them both, and they gave strikingly different results. What gives?

Jennifer evaluated these lenses:

Lens A
Nikkor AF-S VR Zoom-Nikkor 70-300mm f/4.5-56 G IF-ED
$550

Lens B
Nikkor AF Zoom-Nikkor 70-300mm f/4-5/6G
$115

Jennifer asks: "Perhaps you can clarify why these two Nikon lens differ so much. I purchased the first one and then came across the other. Thinking I would be saving myself money, I sent the first one back. Unfortunately, the second one was terribly disappointing. It was clearly inferior, but they seem to be essentially the same lens. If I had started with the second lens, I probably wouldn't have known any better. Fortunately, I had the chance to check out both lenses."

She concludes: "So how do we choose lenses like these? Just by trial-and-error and personal experience over the years?"

The Mysterious Letters Reveal All

It's not just a matter of trial, error, and experience--or dumb luck. These two lenses could not be more different, and thankfully, Nikon spells it all out in the model name. You just need to know how to read it.

Both are auto-focus lenses--that's what the AF means--but there the similarities end. Actually, they are different kinds of autofocus lenses, as well. Let's consider Lens A, the more expensive lens, first.

Nikkor AF-S VR Zoom-Nikkor 70-300mm f/4.5-56 G IF-ED

AF-S is a kind of auto-focus where the focusing motor is built into the lens itself. This designation is important for certain models of cameras that don't have their own focusing motors--they rely on the lens having the motor to focus. But even cameras with integrated focusing motors will let the lens with an AF-S control the focusing, because AF-S motors are typically faster and quieter than what's in the camera body.

VR stands for "Vibration Reduction." This is a feature that gyroscopically stabilizes the lens for sharper photos, especially when you're handholding the camera (as opposed to mounting it on a tripod). Conventional wisdom says that using a VR lens is the equivalent of shooting three stops faster, thanks to less jitter when you hold the camera in your hands.

The IF designation means "Internal Focus"--in other words, the lens doesn't change length or rotate as you focus. This comes in handy if you use a polarizing filter, for example: With a normal lens, you'd have to readjust the polarizer after focusing, but it stays put on an IF lens.

Finally, the ED stands for "Extra-low Dispersion" glass, which is an indication of quality. The glass is engineered to eliminate imperfections like chromatic aberration, which affects the colors in the photo.

Bottom line, this is a high-quality lens. Now let's consider the less-expensive option, Lens B.

Nikkor AF Zoom-Nikkor 70-300mm f/4-5/6G

Notice the lack of abbreviations? Essentially, this is a hunk of glass. Don't get me wrong; I like Nikon lenses. Even a cheap Nikon lens is built to a certain quality standard. But this lens isn't especially high in Nikon's hierarchy. The AF indicates it's auto-focus, but it'll only focus on Nikon bodies that have integrated focusing motors. There's nothing else remarkable about this lens.

Evaluating Other Lenses

Those codes will help you unlock most of the common features in modern Nikon lenses, thought there are other Nikon codes out there that I didn't talk about. And Canon has its own designations, like EF and EF-S. I could write for days about the codes and model names used by other lens makers. So where can you turn for info to decode lens models?

Wikipedia is a great resource. Here are some pages to check out:

Hot Pic of the Week

Get published, get famous! Each week, we select our favorite reader-submitted photo based on creativity, originality, and technique.

Here's how to enter: Send us your photograph in JPEG format, at a resolution no higher than 640 by 480 pixels. Entries at higher resolutions will be immediately disqualified. If necessary, use an image editing program to reduce the file size of your image before e-mailing it to us. Include the title of your photo along with a short description and how you photographed it. Don't forget to send your name, e-mail address, and postal address. Before entering, please read the full description of the contest rules and regulations.

This week's Hot Pic: "Safari Stripes" by Hendry Oarto, Jakarta

Hendry writes: "I took this photo using a Canon EOS 550D. It is a photo of a zebra walking towards us while we sat in our car at the Taman Safari."

This week's runner-up: "Distant Lightning" by Bob Brennan, Portland, Oregon

Bob says: "I took this photo using a Nikon D300 at Flat Head Lake in Montana. My dog Diamond was playing in the water and a thunderstorm was on the horizon. I held down the shutter button and got lucky on this particular shot."

To see all of this month's winners, visit the November Hot Pics slide show. Visit the Hot Pics Flickr gallery to browse past winners.

Have a digital photo question? E-mail me your comments, questions, and suggestions about the newsletter itself. And be sure to sign up to have Digital Focus e-mailed to you each week.

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