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Close-up: Angle of View, Working Distance & Background Control
The focal length of the lens you use can end up determining a lot of things that can have an effect both on the ease of getting good images and on the images themselves.
As its name implies, a wide angle lens sees a wide angle of view. Conversely, a telephoto lens sees a much narrower angle of view. This may seem obvious, but let's take few minutes this week to consider the implications.
"Working distance" is the term used to describe how far your subject has to be from your lens in order to get the shot you want. The longer the focal length of the lens you use, the more working distance you will have for the same magnification. For example, at life size, you will be 2.8 inches away with the Nikon 60mm micro lens, or 5.5 inches away with the 105mm micro, or an impressive 10.2 inches away with the 200mm micro. If you goal is to photograph stamps, coins or other subjects that don't move around and don't mind you getting very close to them, the shorter lens will work just fine. If you want to photograph butterflies or other small critters that do have the ability to move around and don't really like you approaching very closely, the longer lens will help out immensely. Although the 200mm micro definitely costs more, if it ups your odds of getting the shot you want, it could be money well spent.
As the angle of view changes, so too will the expanse of background you will see behind your subject. With a wide angle lens, you will see a vast amount of whatever is back there. With the narrow angle of view of a telephoto you will see less. When shooting macro with a longer focal length lens, a very small movement left, right, up or down can completely change what you see behind your subject. With a shorter focal length lens though, there's no escaping whatever is back there. You may be able to reposition any clutter than exists, but there's no escaping it.
Shown below is an illustration of the relationship between angle of view, working distance and background control. For each focal length range (telephoto, normal, wide angle) you get a corresponding angle of view. In order to fill the frame with your subject, you therefore will need to be a different distance away for each (your working distance). This variation in angle of view will also mean you will take in more or less of whatever is behind your subject.
So, are there any downsides to longer focal length lenses for macro? Well, yes. They tend to be both bigger and more expensive than their shorter focal length counterparts. This can be a real concern since we do have to carry all this gear around, sometimes on our backs and we are all working under a budget. Some shots just can't be made with a 55mm lens though. Depending on your subject, you'll be quite thankful for the extra working distance. Even more often, the improved background control can make a real difference in the shots we end up with. Think hard before you skimp on macro gear. If well cared for, your lenses will last a long, long time. Make your choices count.
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