A Guide to Camera Lenses
Table of Contents
We ask the question, "what lenses do I need?" This is hard to answer because there are many ways to treat a subject. Many choices depend on your personal taste and ability to carry the equipment. Lens selection is important, especially when you are traveling. There are some general rules for photographing different subjects, but as your photography improves and your style develops you may choose different lenses.
Understanding what each lens does will help you decide whether to use a shorter focal length and move closer to the subject, or a longer focal length and stand further away.
The three types of lens focal lengths are wide angle, normal, and telephoto. Add to this specialty lenses, such as macro and vibration reduction or image stabilizing lenses. Each can help make your photography exciting and a reflection of your way of seeing the world.
A few years ago, if you wanted to save a few dollars, I would have told you to buy a less expensive camera body but spend as much as you could on your lenses. Now, because of digital technology, you need to spend on the camera body as well. Still, I think that you should spend as much on the lens as you can afford. Don't be afraid to look for a good deal, but don't try to save money buy purchasing a lesser-quality lens. The two primary reasons for this are glass quality and speed.
Quality glass is an important consideration because it is what the light passes through to register the image. The better the quality of the glass in a lens, the easier it will be for light to pass through it. This is especially important along the edges of the frame and when you are shooting with the lens fully open. The better the glass is the more expensive it is going to be.
The amount of light able to pass through a lens at its largest aperture is called the speed of the lens. (The aperture is commonly referred to by its f-number). This is the reason that a 300mm lens with an aperture of f/4 wide open will cost you hundreds of dollars. Another 300mm lens with an aperture of f/2.8 wide open will cost you thousands. An f/2.8 lens is twice as fast an f/4 lens. Faster lenses are brighter to look through because they allow more light into the lens and can be used in lower light conditions. They allow you to use higher shutter speeds to freeze the action in low light conditions. If you shoot from the hip in a market place, without time or freedom to set up a tripod, a faster lens allows you to get good sharp images. Generally, faster lenses are also heavier because they have more lens elements. My 500 mm, f/4 lens weighs eleven pounds.
I am not telling you that without the fast and expensive lenses you won't be able to get good results. The more expensive lenses will typically expand your potential. Before you refinance your home to buy new lenses, lets think about what your needs and choices are. If you can afford it, buy the best. If you are like most of us, you will end up with some fast and some slow lenses. Understanding that you may make some compromises, here are guidelines to keep in mind when purchasing new lenses (or other photographic equipment):
- What can you really afford?
- Having a realistic idea of what you can afford will save you anxiety and decision making right away.
- What are your needs?
- Do you really need the faster lens or will one a little slower be everything you will really ever need?
- How often will you use it?
- Are you buying this lens for a special once-in-a-lifetime trip or will it be something that you use on a regular basis?
- Can you carry the weight? Three or four heavy lenses can make your photo endeavors more of a chore and less of a pleasant experience. This is not only a question of whether you can carry the weight, but can your mode of transportation carry the weight? Remember, when you are traveling you may need to use small planes with strict weight limits.
Now we look at the three general lengths of lenses and learn what they are used for. Wide-angle lenses give the widest picture angle and extra depth of field. Although there are extreme wide-angle lenses, such as 13 and 18mm focal lengths, most wide-angle lenses cover the 20 to 35mm focal length.
My fondness for wide-angle lenses did not develop until late in my photographic career. I was stuck with a belief that wide-angle lenses were only for landscapes. I always had a wide-angle lens in my bag, but I fell into the hole that many wildlife photographers fall into and tended to think only with my biggest lens in mind. Once I realized the potential of wide-angle lenses, a new way of making photographs presented itself to me.
Wide-angle lenses add depth to the subjects you are photographing and include more of the elements you see in the photograph. They stretch out your depth of field and allow the viewer to understand the immense grandeur of inspirational landscape. It allows you to see the forest and the tree, and to experience the solitude of a single person walking along a deserted beach.
Wide-angle lets you focus on objects close to you that will lead the viewer into the photograph. One of my favorite uses is to get down low, with my subject in the foreground, and include the habitat my subject is living in. When photographing close to an object, it is important to know that wide-angle lenses can distort the foreground and make the subject appear closer than they really are. A hand reaching toward the camera will seem enormous or the nose on a person's face will seem bigger than the rest of their head. Although you should be careful of this, it is also a technique you may use to accentuate a subject in the foreground. Use a wide-angle lens and find a new way of seeing things around you.
During one of my trips to the Galapagos, the only lens I brought with me was a 24mm lens. This was an ideal place to test my theory because the wildlife there is so approachable. Taking care not to disturb any of the animals, I was able to place the lens close to wildlife and still include the dramatic landscapes around them. These wildlife landscapes have become favorites of all the photos I have ever taken there.
Wide-angle lenses are ideal for tight spaces with limited space, such as a crowded market or the inside of a Masai home. They let you include big picture elements of your experience, such as a portion of the boat the whale is next to. The person looking at your photos can imagine what you saw as if he had been with you. You will find a wide-angle lens to be an invaluable part of your field gear.
What does "normal" lens mean? The photo produced by the normal lens gives you about the same viewpoint as the human eye. The normal, or 50mm, lens has been much maligned because it is the lens most cameras come with. People can develop a dislike for the common; it's just not unique enough for them. But what is the potential for any one piece of equipment?
50mm lenses see the world at the same focal length that we see through our 50mm eyes. This can be a big asset for grab-and-shoot street photography. When you see something that catches your eye, you can capture the moment just as you see it. Normal lenses are typically fast and have close focus range. It is a versatile lens. 50mm lenses have largely been replaced with short zoom lenses that cover the 50mm range and more, but it gives you a realistic view of the world that should not be overlooked. I cover the range of the normal lens with my 28 to 70mm zoom lens.
Telephoto lenses are the workhorses of the wildlife photographer. They are separated into three categories: short, medium, and super telephoto range. All telephoto lenses share the same qualities, and these are the points you should consider when choosing which to use.
Telephoto lenses do not bring you closer to the subject, rather they isolate the subject from its surroundings. The only way to get closer to your subject is for you or the subject to get up and move. If you think of telephoto lenses this way, you will compose better images.
Another quality of telephoto lenses is they compress the field of vision. Objects that look far apart with your normal eye become compressed when you look through a telephoto lens. This makes the telephoto lens ideal for photographing some landscapes. If you want to make the peaks of mountains seem like they are right next to each other, use a telephoto lens. If you want to silhouette the elephant against the setting sun, use a telephoto. Knowing the nuances of your equipment will open you to new results.
As magnification increases, depth of field decreases. This means that because telephoto lenses magnify, they have a shorter depth of field, especially at larger apertures. This can be a benefit if you are trying to blur uninteresting backgrounds that detract from the picture, but it also can be a detriment if you are photographing a bear up close and want the area from the tip of his nose to the back of the head to be in focus. This is fixed by understanding the different values of your aperture at specific magnifications. How do you learn what the different values are? Practice with your lens and do testing before you go on a trip.
How big is enough? For wildlife photography, a minimum of 300mm is required. There are destinations where the wildlife is used to people and you can get extremely close. In these cases, a 300mm lens is sufficient, especially if you are using a digital camera that increases the focal length of your lens by as much as 1-1/2 times. Adding a teleconverter will also increase your focal length. A 1.4 teleconverter (find more about teleconverters at the end of this chapter) will bring the focal length of the 300mm lens to 420mm. This will fill the needs of many who travel to photograph wildlife. A 300mm is ideal for zoos, sports, and places such as the Galapagos Islands. So if you are a person who only photographs wildlife on an occasional basis, it might be hard for you to justify the expense of a longer lens. If you plan to photograph wildlife on a regular basis, consider a lens in the 400mm to 600mm range.
If my primary interest were bird photography, I would consider a 600mm lens, but I shoot a variety of subjects and the 600mm is more weight than 500mm. I prefer the shorter lens. If you are considering buying a lens in the 400 to 600mm range, remember that the speed of the lens is very important (see the section on buying lenses at the beginning of this chapter) and the faster the lens the more money it will cost. Lens quality is what is important, so if you need to save dollars to buy the better lens, it is probably worth the wait.
When zoom lenses first came out, the quality of the lens was never as good as the quality of a fixed focal length lens. As technology improved, so did the quality of zoom lenses. Today, zoom lenses are sharp and are used by professionals without hesitation. As in every other choice in photography, there are advantages and disadvantages to consider.
Zoom lenses have become very popular for one important reason, they are convenient. They allow you to have more creativity in composition without the hassle of changing lenses. When you are traveling, the weight and amount of equipment you can carry with you is a major concern, and zoom lenses provide a very easy way of dealing with this problem. Many zoom lenses are compact, lightweight, and fit into a camera bag small enough for you to keep them with you on the smallest airplanes.
Another advantage of zoom lenses over fixed focal length lenses is the ability to change the focal length while you are looking through your camera. This will help you decide upon your composition. If you are not sure if you want to fill the frame or add some background, you can do both with a mere turning of the lens. Zoom lenses have a big advantage when photographing people in market- places or at events. They allow me to zoom in on the person when having to move in closer might disturb the mood.
There are two disadvantages of zoom lenses: durability and (to a lesser extent) speed. Since there are more moving parts in a zoom lens, they are inherently more fragile than a fixed lens. This does not mean that they are so delicate you should be worried about them breaking at the least little tap, but it does mean that over time the chances of a malfunction in a good quality zoom is greater than that of a fixed focal length lens. Manufactures may disagree, but from personal experience my zoom lenses have needed more repairs than the other lenses in my gear.
Many zooms are much slower than the same range in a fixed lens. There are exceptions, but they are very expensive lenses. With new technologies in lens manufacturing, speed is becoming less of an issue. Many new zooms are very fast lenses, but this is not always the rule. Even though it is becoming less of an issue today, speed is still a major consideration, especially in longer focal lengths and action photography where speed is essential.
Another disadvantage of the zoom lens to me is an advantage to others: you have choices in the composition of the exposure that can make too many things to think about. I know what an image through a 300mm lens will look like. Which do I use? I have both types and decide which to use based on the limits of the destination and the subjects I will encounter. Even with a fixed lens bias, I realize that having one lens that takes the place of two or three is a big convenience and a relief to my back.
The feature of lens stabilization is called Vibration Reduction by Nikon, while Canon calls it Lens Stabilization. It is a built-in gyro that reduces the amount of movement detectable by the camera. This is extremely handy when you need to handhold your camera, such as when you are photographing from a rocking boat or in windy conditions. These lenses are often slower than conventional lenses, however the ability to stabilize makes up for the loss of speed in the lens. This feature on big lenses helps tremendously when you are panning on a tripod or using a less-stable platform to photograph from, such as a mono-pod. Still, nothing beats a tripod, so don't think stabilization is a replacement for using one. This is a perfect example of technology freeing photographers to concentrate on making the image and not having to be as concerned about the environment.
Whole books have been written about close-up photography and it is a wonderful and exciting way to record the smaller things around us. There are lenses that have close focus ability, but for truly macro photography close focus does not give you the same results as a true macro lens. Macro lenses give true 1:1 ratio so images will be life-size reproductions of small subjects. Whereas in most photographic applications photographers are typically looking for the fastest apertures in lenses, macro photographers go the opposite way and look for the greatest depth of field.
As magnification increases, depth of field decreases. Macro lenses let you get in close (magnifying your subject) and have the smallest apertures allowing for greater depth of field. Since the smaller apertures will also increase your exposure time, stability is very important here. The use of a tripod, beanbag, or some other steadying device is a requisite for macro photography.
An exception to this rule occurs when you use a flash to give you enough light to work with higher shutter speeds. Since you probably will be photo-graphing objects very close to the lens, you need to have your flash mounted on a bracket to ensure that your subject is properly lit during the exposure. In many cases, two flashes are required to prevent unwanted shadows or to illuminate the background as well as the subject. There are many brackets avail-able. If you are thinking of using one, shop around to find one you are comfortable working with. An alternative to mounting flash on a bracket is to use a specially designed ring flash or close-up flash. These flashes attach to the front of your lens and allow you to get into tight spaces where a flash on a bracket would be obstructed.
Various manufactures make different size macro lenses. 60mm, 105mm, and 200mm are the most common sizes of macro lenses.
Like all specialty lenses, macro lenses can be more expensive than non-macro lenses. If you enjoy making the occasional close-up image but are not serious enough about macro photography to buy a macro lens, there are less expensive alternatives that even the serious macro photographer might consider when traveling. Extension tubes or close-up filters are a good way to take macro photography. (I use the word filter here for the sake of clarity, they look like a filter that you put on the end of the lens. In fact, they are called close-up lenses.)
Macro lenses can open up new alternatives for your work. Bring one into a field of wildflowers or garden and you will be surprised at how much wildlife you can discover. Whoever said they would photograph more often if only there were something around their home worth photographing never went looking with a macro lens. Plants, insects, and spiders all are subjects o explore with your macro equipment. You probably can find them all without leaving your own yard.
For traveling purposes, macro lenses are less appropriate for some destinations,while others seem to have been created for macro photography. On an African safari, macro work can be done at your lodge site, but on game drives it will be rare for you to leave your vehicle and use macro lenses. The tropical rain forest, on the other hand, is a macro photographer's dream come true.
Extension Tubes and Close-up Lenses
Extension tubes go between your lens and camera body, adding space between the plane of film and the end of the lens. This changes the focusing capability of your lens, allowing you to get physically closer to your subject. By moving close to your subject, you increase the size of the subject in relation to how much of your frame is filled. This is an ideal way of getting close-up photography. There is no glass for the light to travel through so there is no distortion in the final result. You still need more exposure time, because the added distance between the lens and film causes a loss of light. Extension tubes are less costly than a true macro lens, and I recommend original manufacturer extension tubes to keep the metering system as true as possible.
Extension tubes are useful for more than just macro work. They enable you to focus closer than your lens will normally allow. This means it will focus on subjects closer to you. If your subject moves too close for you to focus, add the extension tube and presto, you can focus correctly.
Extension tubes cut down on the amount of light passing through the lens and you should expect to lose about a stop of light when using them.
Supplementary close-up lenses look like filters that screw onto the end of your lens and magnify the image. The lenses themselves come in different magnification, so by stacking them you can achieve stronger degrees of magnification. If you use close-up lenses, be aware that stacking may make the frame of the lens visible in your viewfinder and cause vignetting. Close-up lenses range in price from inexpensive too extremely expensive because the better the glass in the lens, the higher the cost. As with any lens, the better the glass the better the resulting image.
Whether you use an extension tube or a close-up lens, you will be able to use these as macro lenses without adding too much weight, bulk, or expense to your equipment.
Teleconverters, also called extenders or multipliers, are an inexpensive and convenient way of increasing the focal length of your lens. Teleconverters are placed between the lens and camera body, and they typically come in tree magnifications: 1.4X, 1.7X, and 2X. The 1.4X teleconverter effectively multiplies the length of your lens 1.4 times. The 1.7X multiplies it 1.7 times. The 2X doubles the length of the lens. 1.4X and 1.7X may seem like odd multiples, but they give you outstanding resolution while increasing the length of the lens. The 2X is stronger, but the resolution is not quite as good as the 1.4X. Although the 2X and 1.7X are very popular in the amateur audience, the 1.4X is more popular among professionals.
Teleconverters are less expensive than buying a new lens and they are a convenient way of adding length without having to carry another lens. A 1.4X teleconverter added to a 300mm lens gives you the equivalent of a 420mm lens, while adding a 2X teleconverter will effectively give you a 600mm lens.
If teleconverters are so handy and less expensive, why would you want to buy long lenses in the first place? The answer is light. When you add a teleconverter to the lens, you decrease the amount of light able to pass through the lens. With a 1.4X teleconverter, you lose about one stop and with a 2X teleconverter, you lose about two stops.
You can buy an inexpensive teleconverter, however I recommend the original equipment manufacturer's brand when buying a teleconverter that are made for your lenses. Adding one to the lens for which it was made will make it more like another lens and less like a lens accessory.