Sunday, July 18, 2010

Lenses: Introduction

From time to time I get photography questions from co-workers, Facebook contacts or perfect strangers who see me shooting on the street, so I've decided to compile some of the answers I've been giving them. For lack of a better name, I'm going to call these blog entries Stef's Photo Tips, and I'm going to start with a disclaimer.


These photo tips are not intended for professional photographers, or even for experienced amateurs. If you know exactly what F/3.5-5.6 means, this is not for you; it's for your father-in-law who just bought his first digital camera. If you want advanced information about lenses, shooting techniques or the latest new gadgets, resources abound on the Internet, and I'll be listing some of them at the end of each photo tip article.


Because it's probably the question I get asked the most, I'm going to inaugurate this new blog feature with a discussion of lenses.

If you bought your digital camera as a kit, it probably came with a lens that is far from the best your camera manufacturer can do. Kit lenses are usually zooms, because manufacturers and retailers are aiming for a market of consumers who will seldom be changing lenses, if at all. Some of these zooms can be fairly decent, but if you're thinking of getting a new lens, you might want to do a bit of research before you go out and buy a more expensive zoom to replace your kit zoom.


A lot of people are attracted to zoom lenses because they're practical. Instead of packing five or six different lenses in your camera bag, you need only one lens to cover a wide range of focal lenghts – such as 18-105mm or 18-200mm. Zoom lenses with wider ranges tend to be more expensive, and some people may think that they are better. In most cases, they are not.

Zoom lenses are much more complex to manufacture than fixed lenses. For this reason, manufacturers tend to "cut corners" in order to be able to offer a competitively-priced product that will meet the needs of the average consumer. Setting aside the professional-grade zoom lenses, which are too expensive for most people to consider, most zoom lenses will usually feature lower-quality optics, which means lower-quality pictures, and a barrel made of plastic instead of metal, which means that these lenses will not be as sturdy as fixed-lenght lenses. The wider the zoom range, the more difficult it is for manufacturers to build a lens cheap enough to sell on the mass market, and therefore an 18-200mm lens is usually a bigger gamble than an 18-35mm lens in terms of quality.

In optimal conditions, you may not notice the difference. Many affordable, cheaply-made consumer zoom lenses are capable of extremely good performance when shooting landscapes in broad daylight. It's when you try to use these lenses in less than optimal conditions that their shortcomings will become apparent. Most consumer zooms do not have a large maximum aperture, which means that they do not perform well in low-light conditions. Cheaper optics means that these lenses will usually not be quite as sharp as fixed-lenght lenses, and some of them will also produce quite a lot of distortion.


A prime lens is a lens with a fixed focal lenght, as opposed to a zoom lens which offers you a range of focal lenghts from shorter to longer. Prime lenses come in a variety of fixed focal lenghts, and may fall within one of three categories: wide-angle lenses, which have shorter focal lenght and provide a wider angle of view; telephoto lenses, which have a longer focal lenght and narrower angle of view; and so-called "normal" lenses, which are somwhere in between. To put this in plain English, a wide angle lens is what you would use if you were taking a picture of a dramatic stormy sky over a vast landscape; a telephoto lens would be useful to take a picture of a nesting falcon from a distance; and a normal lens is what you would normally use for portraits and family pictures.

There is an additional category of prime lenses which doesn't refer to focal lenght, but rather to focusing distance -- i.e. how close you can get to your subject. Macro lenses are designed to take pictures at very close range, typically of smaller subjets such as insects or flowers. They are usually much more expensive than other lenses, and quite often offer superb optical quality even when they're not used at close range.


Well, that depends what you're going to do with it. If you're strictly into bird photography, for instance, you might want to consider a prime telephoto lens over a zoom lens, because it will give you more optical quality for the money you'll spend. If you're looking for something of better quality to replace your kit lens at family vacations, you should probably look for a prime 50mm lens. And if you do a bit of everything and you're definitely not going to be trying to sell your pictures to National Geographic, then a zoom lens of good quality might still be the right choice for you, especially if you don't especially like the idea of changing lenses.

Depending on your budget, there are a few more factors to take into consideration before you decide which lens to buy. A rugged metal barrel will come in handy if you're going to use the lens in rough conditions, harsh weather or dusty environments; a sturdily-built lens will also be much more forgiving of getting bumped or even dropped. Nikon and Canon both offer lenses with vibration reduction systems, which can be helpful in getting sharper pictures; these systems will also add up quite a bit to the price of a lens. If you're going to be using the lens in low-light situations, by which I mean anything other than out of doors in broad daylight, you might want to take a look at so-called "fast" lenses, which have a wider maximum aperture and allow more light to get into the camera. A wider maximum aperture can also translate into a significantly higher price, and while fast lenses generally tend to be well-made, you should remember that faster and more expensive does not necessarily mean better.

As with buying a car or a computer, the important thing is to do your research before you buy. Don't let salespeople dazzle you with technical jargon, don't let self-proclaimed experts assure you that "this is the only lens you'll ever need", and don't let anyone pressure you into buying something before you understand what you're paying for. Ask a lot of questions, and if the salespeople are unwilling or unable to answer them in plain English, go somewhere else.


I don't get any money from Nikon and I'm not one of those Nikon users who think everything else is worthless, but because I am a Nikon user, most of the resources I know about are either Nikon-heavy or Nikon-specific. If you're a Canon person or a Pentax person and you happen to know about a useful link, please send it on and I'll be happy to add it to the list.

Ken Rockwell is vastly sneered at in the professional photography world, not without good reason in some instances, but I'm including him here because he writes in plain English and he's tested a positively staggering number of lenses. Just remember to double-check any bold statements he makes about one lens or another being the best invention since sliced bread.

If you have a Nikon and you want to do some research on Nikon lenses, the very best resource in my opinion is Thom Hogan's web site. The language can get a little technical, but Hogan does provide a handy five-star chart summarizing the strenghts and weaknesses of the lenses reviewed.


In my next photo tip article, I'll be taking a closer look at the alphabet soup that constitutes a lens name (e.g. Nikon 55-200mm F/4.5-5.6 VR), and what each of these hieroglyphs means to you in terms of taking some actual pictures.

Happy shooting!