 | |  |
|  |
One of the really neat kinds of pictures you always see in magazines is the extreme nature close-up. Sometimes it's a bug, with every facet of the compound eye glittering. Sometimes it's a flower, or even a rock. This kind of picture is the stock in trade of macrophotography. Everybody, or nearly everybody, with a decent camera and set of interchangeable lenses can take macro pictures in some way or another, but not all these different approaches are going to produce results like those of a magazine.
It may sound simple, but macrophotography is just getting close-up pictures. If you attach a lens to your camera (not a big telephoto, please) and, starting about five feet from a subject, start moving in closer, you'll find that for a while the camera will focus correctly but at a certain point (usually about three feet) the camera/lens will no longer focus. The problem is that the image at this distance isn't very big; your bug will look like a speck instead of a science-fiction monster. You need to get closer, and that's were the options start.
One option is to get a telephoto lens that focuses reasonably close. My Nikon 80-400 doesn't focus all that close but racked out to 400 it can still take a flower or insect shot. In some cases, this is a good strategy because you don't alway want to be all that close to something you're photographing (a puff adder in Africa comes to mind), and you don't have to cart around an extra lens or change lenses and get dust in the camera.
Another option is to use a close-up lens. This is a clear lens that screws on the front of your main lens like a polarizer or other filter. These lenses usually come rated for "+1" or "+3", etc. where the plus and the number provide the diopter, which roughly means the magnification. The higher the plus number of a close-up lens, the closer to the subject you'll get and the bigger the image will look on your film plane or CCD. If your camera can use filters, you can use this strategy…sort of.
The problem with close-up lenses is…well, there are a lot of them to be honest. First, you get image size by getting close. Your bug may not want you one and three-sixteenths of an inch away. Even if he doesn't mind (because, for example, he's dead), your camera, head, and body may mess up the lighting. If the subject isn't dead and isn't all that happy about close encounters of the camera kind, it may react by flying, running, or even biting. Then there's the depth of field, which is pretty much non-existent. It's very hard to focus, and to keep any significant part of what you're photographing in focus. Finally, most people will admit that close-up lenses tend to create soft pictures, lacking the crisp detail that you usually want. Plan B time.
A third approach is to use a lens (often a zoom lens) that has a "macro" setting. Take a look at the specifications for your lens, and you may see that it provides macro or close focusing. For example, my Sigma 24-70mm f2.8 EX will focus down to 15.7 inches. The specifications will also tell you just what that means in image size, usually with a ratio value. For the Sigma, it's 1:3.8. That means that the image on the CCD of my D2X will be one divided by 3.8, or about 27% of life size. Something really an inch long at my minimum focus distance will spread out to only about a quarter-inch on the CCD. From this, you can deduce that a macro setting that gave you "life size" where the size of the image on the CCD or film is equal to the real size of the bug, would be rated as 1:1.
Most wide-angle zoom or wide-angle lenses will have a macro setting that will give you something like this quarter-sized image. The photo of the mantis above was taken with the Sigma lens at just about the minimum focus distance. If the lens is decent, you can get adequate depth of field and sharpness, but even on this shot the leaves show how shallow the depth of field can be.
If you want better shots than you can get with a macro setting on a standard lens, you have to go with a macro lens. These products are relatively expensive (about one-and-a-half times the price of an equivalent fixed-focus lens), but they'll always offer you the 1:1 size option, meaning that you can get a bigger image of a given subject.
Macro lenses usually come in various focal lengths, from about 50mm to about 180mm. All will provide 1:1 reproduction, with the difference being how close to the subject you need to be in order to get the specified size. Using Sigma as our example, the 50mm lens will achieve 1:1 at 1.6 inches, the 105mm at 4.7 inches and the 180mm at 9.5 inches (all of these are from-the-lens-to-subject distances). The shorter focal length lenses are cheaper, obviously. Note that macro lenses will also work as "standard" fixed-focus lenses, so they're often used for portraits and for other applications where extreme sharpness is the goal.
A fourth approach to macrophotography, and one sometimes used in conjunction with other approaches, is based on why lenses won't focus close. As the subject gets closer to the lens, the focus point falls back behind the film plane/CCD. If you just had a way of moving the lens out from the camera body, the closer object could be brought into focus. This is the principle behind extension tubes or bellows attachments. The tubes are just that-tubes that connect the lens to the camera. The bellows is a kind of "old-camera" artifact, an expanding accordion-like contraption that lets you adjust the distance between the lens (mounted on the front of the bellows) and the camera (attached to the back). The problem with these goodies is that most won't work with autofocus lenses, and some camera vendors will warn you not to use them. We'd consign this third option to the "professionals only" category.
If you view macrophotography as an occasional gambit, I'd recommend that you find a wide-angle or zoom lens that has macro focusing and use that as your strategy. This will usually work out good for flowers and larger insects. If you want something better, it's time for a macro lens.
When selecting a macro lens, buy the best brand or model you can get. Sharpness of the lens is critical at these distances. If there are multiple focal lengths offered, the rule of thumb is that shorter lenses mean getting closer to the subject, so you may want to consider the 180mm or 200mm lens if you can afford it.
Some macro lenses will permit mounting a teleconverter, which will either give you 1.4:1 or 2:1 (larger-than-life) images at the normal working distance or 1:1 at a greater distance. If you're interested in extreme close-ups without buying extension tubes or other hardware, be sure that your macro lens will work with a teleconverter.
Another thing to think about in macro lens purchasing is the utility of the lens in non-macro applications. As I noted above, you can use any of these lenses in standard mode. How useful will your macro lens be in that mode? Let's take the Sigma trio as an example. The low end is the 50mm f2.8, which isn't likely to add much versatility in normal lens applications. Next up is the 105mm f2.8, which is a low-end telephoto and probably nice, but which won't work with a teleconverter and doesn't offer the high-speed motor focusing. The top of the line is the 180mm f3.5, which works with teleconverters and has the high-speed motor focusing capability. You lose a half-stop of speed for the latter lens, but it works at twice the distance as the 105mm even without the teleconverter, and nearly four times the distance with a 2x teleconverter attached (all of this to get 1:1 reproduction). Furthermore, the 180 is a pretty nice telephoto size for general use.
For digital camera users, remember that the "digital multiplier" works on macro lenses as well. A 1:1 lens will give you a 1.5:1 reproduction, or offer 1:1 at a greater distance. Add a teleconverter and a digital camera and 180mm macro lens will provide about 3:1 reproduction at the closest working distance. Ant eyeballs? It's at least in the range of practicality. Remember, 3:1 means the image on the CCD is three times life size, so a good sized ant would actually fill the frame.
Macro technique is its own set of issues. Obviously one of them is whether you can get close enough to your subject to get the desired magnification, which is where the longer focal length macro lenses shine. Others are lighting, depth of field, and shake. All of these relate to the question of camera setting.
Here's this great bug, you think. Let's get a shot. You set up your camera and…well, what do you set it to? On the one hand, the bug isn't going to sit there posing all day, and even a little camera shake will be a disaster at 1:1 reproduction. That suggests that you pick a nice big lens opening so you get a fast shutter speed-maybe 1/250s to 1/500th of a second. Only if you do that, your depth of field will be about a fiftieth of an inch. . Even on an ant, that's not much distance, and you might well get the ant's antennae in focus but not its legs. OK, you say, let's get a bit more depth of field so we'll stop down to f8. That's great for depth of field (you probably can get almost an inch, which is big on an ant), but now your shutter speed is down to 1/60th second, so you can't have any shake or movement or there'll be blur.
There's no magic answer to this one. All you can do is to shoot at the highest ASA that will keep grain or digital noise to acceptable levels, and then set your shutter speed based on how steady your rest is (use a tripod) or how much your subject moves.
It's also wise to remember that the benefits of the longer macro focal lengths aren't without a price. Depth of field is smaller with the longer lenses, just as it is with normal telephoto lenses. At roughly 1:1 distances, and at f8, a 50mm macro lens has a depth of field of about 7/100s of an inch. The 180mm has half that. You have to weigh these factors when considering which focal length is best.
Another question that sometimes arises with macro lenses is the f-stop. Is an f2.8 better than an f3.5? In nearly every case, not for macrophotography. It's rare to be able to shoot macro "wide open" because of the very shallow depth of field. Moral: Don't worry about f-stop differences for macro work; only if you're strategizing your non-macro use of the lens should this come into play. Also keep in mind that from f2.8 to f3.5 is a half-stop, which won't make an enormous difference.
Using a strobe would seem a good answer to the macro problem, because not only does it create a lot of light it also has a short duration flash that tends to freeze motion. The problem is that most standard electronic flash units won't illuminate at macro distances, and some cameras won't even meter flash that close. There are special "ring strobes" that put the flash as a ring around the lens to get it in the same plane as the macro subject (if you watch crime shows, you see the forensic team using them), but they're expensive. You may have some luck with taking the strobe off-camera with a cable and holding it to one side, but it's a good idea to test this lash-up on some still life photos first to be sure that the camera will handle the exposure OK. If your camera has a fancy three-dimensional flash metering calculation, it may be necessary to disable it and go to a simpler flash mode to handle macro distances. Another advantage of the longer tele-macros like the Sigma 180mm is that standard flash may well work for you with these lenses. I find that I can shoot a butterfly with the 180 using either the Sigma's built-in flash or my SB-800.
If direct sunlight isn't an option and you don't have or want a flash you might want to consider reflectors. White board or paper will reflect light, and setting up some reflectors near the subject may provide you better lighting than ambient light offers, and more control than electronic flash. Obviously, using any form of reflector probably means setting up in advance, but since many bugs and birds frequent the same spots, that may not be as difficult as it first sounds. In fact, if you're trying to capture birds or small mammals, pre-planning is probably a key element to macrophotography. Pick a spot where something attracts your subject, set up a tripod and deal (in some way) with the lighting issues, and then wait. Sometimes using a remote release on the shutter (radio control, air bulb, electronic remote, or just plain cable release) will let you stay far enough away to avoid startling the thing you're trying to photograph. Remember, the higher up on the biological chain the critter is, the more likely it won't sit for photographs. Bugs are easy; birds and mammals are much harder.
My own approach to macro lenses and macro photography is based on the Sigma 180mm f3.5 EX HSM macro lens. This lens, acquired in the spring of 2003, was selected based on the criteria that I've outlined above. It's a big lens, as large as the 70-200mm zoom from Sigma, and heavy (but to somebody who carts around a 500mm telephoto, the macro is a cakewalk!) as well, but the benefits of this lens are clear. Not only is it incredibly sharp (a characteristic most decent macro lenses possess), the long focal length lets you stand back from the subject to get the picture instead of hitting it on the nose with the camera.
Obviously, you're not going to get a macro lens to do normal-distance photography, but it's important to remember that all of them work as standard lenses. Generally they're sharper than an equivalent fixed-focus normal-distance lens, and they're always sharper than a zoom. Some photographers use their macro lenses as their standard medium telephoto lens, and there are definitely times when that's a good idea. The Sigma tele-macro is a great "nature walk" lens; it's decent for a shot at a bird or animal because on the D2X it's an effective 270mm telephoto, and you can close in on a flower or bug if you want to. When I was wandering through Yellowstone a couple winters ago, I was often confronted by a combination of great super-close-up opportunities and traditional mid-telephoto shots. If it's snowing, changing lenses can be a real risk. A nice 180mm macro would have been just the right medicine. I didn't have it then, but I do now!
|
|
|
