Lens Buyer’s Guide, Part One

Raptured Scarecrow

Your camera is thoroughly broken in, and you know your kit lens like the back of your hand… its capabilities, its limitations… Its freakin’ limitations. Darnit. So you’ve decided it’s time for a new lens for your camera. Where do you start? Right here, of course.

There are several types of lenses, and while I can’t cover every last one of them (apologies to LensBaby fans, among others), I’m going to cover many of them here. As with yesterday’s guide, I’m not going to get much into brands. The aim, instead, is to familiarize you with your options as a starting point for even more research. Tomorrow, there’ll be another guide that will tell you what you need to take into consideration when you’re buying a new or used lens.

Let’s get started with the normal lens. It’s called that because its FOV (Field of View) roughly approximates that of the human eye. On a full-frame or 35mm camera, a 50mm lens is “Normal,” while on a crop sensor camera, lenses between 28mm and 35mm (42-52mm equivalent) closely approximate a Normal lens. The 50mm 1.8 is a great next step from your kit lens, since its simple optics and small size usually mean a lens that’s fast, light, sharp and cheap. There’s the added bonus that the faster aperture means more control over DOF (Depth of Field), pleasing bokeh (the out-of-focus circles of light that appear in photos taken with the aperture wide-open) , and more options in low light.

When you see a lens referred to as wide or telephoto, they’re using a normal lens as a frame of reference. So a wide angle lens is anything wider than a normal, while a telephoto is anything that gives you a narrower FOV than a normal lens. Your kit lens likely starts at 18mm if it’s a crop sensor (meaning it’s about 27-28mm equivalent), or 24-28mm on full frame. Wide angle lenses are most often used for landscapes and architecture, though some photographers swear by them for other purposes (like street photography) as well. When considering wides – especially wide-angle zooms – pay attention to distortion, especially at the widest end of a zoom lens. Many wides will exhibit barrel distortion, particularly if you’re shooting at or around the lens’s maximum aperture.

Dune Shadows

At the other end of the spectrum are telephoto lenses, which are anything over 50mm. Short telephotos (40mm and 60mm on a crop sensor, 60mm and 85mm on full frame) are popular for portraits because the perspective they offer tends to flatter the subject. Longer telephotos (in the 200-500mm range) are great for bringing the action in close.

Specialized lenses: There are lenses that may fall into one or more of the above categories, but that are designed for particular purposes. Perspective Control lenses are beloved by architects, for instance, because they allow the camera to be kept horizontal while shooting a vertical subject. This is done to eliminate the converging perspective that you’d normally get when shooting from the foot of a building and pointing your camera upward. Fisheye lenses provide a 180-degree field of view, which can be very useful for landscapes and certain types of architectural photography (and, in capable/creative hands, even portraiture). The optics of Macro lenses allow closer focus and often much sharper results than would be possible with other lenses.**

If you don’t have, don’t want, or can’t afford a particular lens, there are times that you can approximate the same effect in post-production (cropping, perspective correction and distortion in Photoshop, for instance, can mimic the behavior of a zoom, perspective control, or fisheye, respectively). Macro photography can be done with inexpensive close-up filters, although the results won’t be nearly the same as using a good macro lens. If it’s something you don’t plan on doing or using very often, there’s nothing wrong with taking a shortcut here and there. On the other hand, if you plan on doing a lot of something, or if the end result is critical (a paid job, for instance), then you’re better off spending the money.


Bear in mind that you can get primes for a huge number of focal lengths between 8mm and 1,000mm (or more), or you can purchase zoom lenses that will cover various focal lengths. These range from wide zooms (like the Nikon 20-35mm) to telephoto zooms like the common 70-300 and 150-500.*** The “trinity” of primes (35mm, 50mm and 85mm) can easily be covered by a single zoom (like a 28-85mm 3.5/5.6, a 24-120mm f/4, or nearly covered by a 24-70mm f/2.8), but bear in mind that there’s a significant tradeoff in terms of speed, and sometimes also of image quality using a zoom. The 24-120mm, as of this writing, retails around $1,300.00, and the 24-70 for close to $600.00 more than that. It’s easy to assemble the trinity and then some (throw in a nice macro, for instance), especially if you’re willing to go with older or off-brand glass. Which brings us to another question: what’s the best way to narrow down to a specific lens and brand? I’m glad you asked. We’ll take that up in this space tomorrow.

*For a more detailed explanation of crop versus full-frame lenses, see http://www.thefirst10000.com/2012/10/full-frame-vs-crop-an-explanation/

**Be aware that not all Macro/Micro lenses are created equal. Some lenses will offer the close focus of a macro, but the optics won’t be as tack-sharp.

***For a detailed explanation of zooms versus primes, see http://www.thefirst10000.com/2011/09/primes-vs-zooms/

Optical vs. Digital Zoom: What it Is, Why it Matters

I was recently in a big box electronics store and was wandering through the camera department when I overheard the following rather dismaying exchange:

CUSTOMER: This one’s got optical zoom, and this one has digital. What’s the difference?
EMPLOYEE: There is no difference. They’re the same thing.

I’m going to give this employee the benefit of the doubt and say that he wasn’t doing what I’ve seen, and been on the receiving end of, so often at chain stores: salespeople who’ll tell the customer anything, as long as it results in a purchase at the end of the conversation. No, we’re going to assume that this guy honestly didn’t know there’s a big difference between optical and digital zoom, or what that difference is. After this, you’ll know the difference, and won’t get snookered.

First off, let’s see what optical zoom is. The “optics” in question come from the lens on your camera, whether it’s the fixed lens on a compact, or the interchangeable lenses on an SLR. The movement of the optical elements (a fancy-ish term for the bits of ground glass that make up the lens) is what allows the lens to focus, and to zoom. Doing either of those things just involves finagling the right combination of movements of those different pieces. Some lenses can have a dozen or more elements, usually arranged in groups; how they’re arranged will affect not only your zoom and focus, but also sharpness and focal distance.

Now that we’ve covered optical zoom, how does digital zoom work? Well, you’ve still got lens elements to handle focus, but they’re being used only for that. The zoom function has nothing to do with the lens. Instead, you essentially have a prime lens on your camera, and the camera’s image processor is taking that image (let’s say it’s effectively 50mm) and cropping it in camera, making it look closer, as if it was shot by a longer lens. This is the same thing that a photo editor like Photoshop or GIMP is doing when you crop an image. The quality of the crop will depend on how much you’re cropping, and on the quality of the resizing algorithm the camera is using, which generally won’t be up to par with even a decent dedicated editing program

The difference between the two should be pretty clear at this point, but in case it’s not: The advantage of digital zoom is sometimes a design consideration (it’s difficult, though not impossible, to squeeze optical zoom into a camera phone), and just as often a cost consideration (precision ground glass, coupled with precision engineering, isn’t cheap). The advantage of optical zoom is that despite the added expense, you don’t have to trade optical quality for the added “reach.” If you’ve already got your camera, and it offers only digital zoom,* my advice would be not to use it. Take the picture at the camera’s native resolution and default focal length, transfer it to a computer, and crop it then. You’re still starting with the same initial photo that the camera would be before it “zoomed,” but you’ll be using better software to crop, and should get a better result because of it.

*Or if, like many compacts, it offers optical up to a certain point, and then switches to digital past that