Macro Lenses

The 50mm lens I carry in my standard day hike kit is a specialized type of lens, called a macro lens. A macro is specially designed to take close up photos, although it can focus to infinity as well. I'm a big fan of wildflowers, so I never go on a shooting trip without my macro lens. The close focus range of a macro lens is normally described as a ratio, such as 1:2, which means that the subject appears at 1/2 life size on the film. When the film is printed, the image gets enlarged beyond this ratio. Some "macro" zoom lenses have macro ratios like 1:8, which is pretty lame; that's not close focusing at all.

Many macro lenses have focal lengths in the medium telephoto range; 90mm, 105mm, and 135mm macros are fairly common. Some people find the extra working distance allowed by the longer focal length to be indispensable. Well, it all depends on your subject material. If you are shooting, or regularly shoot, frogs, bugs, or other things that can hop, fly, or slither away when you annoy them; you'll want the longer lens. The shorter lens has the advantage of greater depth of field, which is particularly important at close range.

Other ways to focus close

While there's really no good substitute for a genuine macro lens if you want to do serious close up photography, a well stocked camera store will have two relatively inexpensive options for close focusing. They have serious drawbacks, but might be acceptable for certain applications.

One such option is the diopter close up lenses. These lenses screw onto the end of your standard lens, in the same way you would use a filter. They are generally sold as a set, with three lenses designated +1, +2, and +3; with the +3 providing the closest focusing capability; they can also be stacked, allowing even closer focussing.

These lenses provide the capability to create a close up image that is reasonably sharp at the center of the frame, but the fall off in sharpness as you look towards the edges is horrifying. If you are taking a simple flower portrait, and you want the background to be a pleasing blur, that might be OK. But what if the subject is a flat leaf that fills the frame?

Another option is extension tubes. They mount between the camera body and your standard lens. If you watch your standard lens as you adjust the focus, you'll notice that it extends forward as you focus closer. The extension tube just carries this principle farther by adding extra space between the film and the lens elements. Extension tubes are generally available singly or in sets, the longer the tube, the closer you can focus with it. Extension tubes work well on some lenses, and dreadfully on others. Due to some quirk of optical voodoo that I don't understand and is way beyond the scope of this book anyway, some lenses steadfastly refuse to create sharp images up close. I tried an extension tube on my 70-150mm zoom once, and couldn't get a remotely decent image.

I find tubes to be extremely useful in conjunction with my macro lens. Since it is specially designed to focus close, I can get images that are sharp edge to edge at a 1:1 macro ratio or even higher with a tube; without the tube, I can only focus to 1:2.

Lens Hoods

There are a few accessories which you may, or may not, want to attach to your lenses. The first one is a lens hood, which is a devise at the end of a lens designed to block out light which might hit the front element of your lens at a weird angle. This weirdly angled light, if left unblocked, could cause lens flare, which can manifest itself as light hexagons, rays, or streaks of light on your image. Sometimes lens flare can be kinda neat, but generally it should be avoided.

Some lenses, mostly telephotos, come with built in hoods. These are usually a simple tube which slides out past the front element of the lens, a simple and effective arrangement. Unfortunately, stopping those nefariously angled light rays is harder with a wide angle lens, since wide lenses are gathering critical image light over a wider angle, so one of those tube style hoods would block out the edges of your image.

Most add-on accessory hoods are rubbery things which screw onto the filter threads at the end of the lens. They usually fold up when not in use. These rubbery hood have an extra advantage: they offer some protection to your lens from bumps and dings and stuff; they are like rubber lens bumpers. There are special hood available for wide angle lenses; they help prevent lens flare, but since they are angled out to keep the whole frame bright, they are not as effective as hoods for standard or tele lenses.

You'll need to train your eyes to look for flare when you're shooting. Assuming that you're using an SLR, the flare should show up in your viewfinder.

Dr. Garth's Prescription for Improving your Photography #897:

Watch out for lens flare! If a lens hood doesn't help, try slight adjustments to your camera position. If you can't eliminate the flare that way, hold your hand between the sun and the front of your lens while you're looking through the viewfinder. Usually, there's a perfect spot where you can hold your hand where the flare is eliminated without your hand showing in the photo.

Filters

The other major category of lens accessories is filters. The importance of filters is often exaggerated. At crafts fairs or exhibits, people frequently ask me what filter I used for a particular shot; they seem to assume that filters are an important part of serious nature photography. In fact, I seldom use filters at all. I carry a polarizer, but I don't use it very often. That's not to say filters are never useful, however. Let's look at some types of filters and when they might be useful.

Polarizers

The most useful type of filter is a polarizer. I don't want to explain the physics of how these work, since I don't have a real great, in-depth knowledge of it myself, so we'll jump right to the pragmatic stuff about what they do. Basically, polarizers do two useful things: they reduce reflections, and they darken blue skies. Polarizers are adjustable; you can rotate the front section to control the degree of polarization. Look through the viewfinder while you rotate the filter so you can optimize the effect.

While the darkened skies polarizers produce can be quite striking, there's a downside: the effect varies with the Sun's angle to the camera, so with a wide angle landscape part of the sky will wind up really dark, and part of it will be really light. The result can be kinda surreal.

As to polarizers ability to reduce reflections, I seldom have the urge within the realm of nature photography. Reflection reduction can be useful in civilization photography if you're shooting through a window and want to see what's inside instead of reflected glare, or in portraiture if your subject is wearing glasses. But in the natural world I usually like the reflections. A couple of circumstances come to mind where reflection reduction might be nice, however: shooting tide pools, so you can see the critters better; and lanscapes with lots of glistening wet leaves, where the polarizer would help get more saturated leaf color.

Polarizers can also be used as a substitute for another type of filter that's occasionally useful: the neutral density filter. ND filters are like sunglasses for your camera; they're useful when you are shooting in bright light and you want to show the motion of your subject. Sometimes, stopping down all of the way leaves you with an shutter speed around 1/60th, and that may not be slow enough for the effect you want.

Filters for slide film

Those of you who are foolish enough to use slide film will probably need another filter or two in your field bag. One filter you'll probably need is a warming filter, such as a #81A. This compensates for the slightly bluer light in the shade, versus the yellower direct sunlight for which the slide film is optimized. With negative film, any minimally competent printer will make this correction for you, so you don't need the warming filter; of course any incompetent printer will mess up your images anyway, so a warming filter won't help then either.

There are also a flock of split neutral density and grad-grey filters out there, which, at least in the abstract, should be useful when shooting slide film. In theory, you can balance a bright sky with a darker foreground by using one of these partially grey filters; the grey part reduces the exposure of the sky relative to the foreground, so that the sky stays blue without the foreground getting too dark. In theory.

The practical problems abound, however. These filters pretty much always have the division between grey and clear in the center of the frame. The division, whether gradual or hard edged, is straight. How many interesting nature photos have you seen with a straight horizon line smack dab through the middle of the frame? Not many. If the filter's greyness doesn't correspond pretty closely to your horizon, it will show up as regions of unnatural darkness or lightness. Most negative films have much greater brightness range, so you shouldn't need to resort to these goofy filters to keep the sky and foreground exposures balanced, assuming you expose correctly. You might need custom printing occasionally, however, to darken the sky and/or lighten the shadows.

Filters for black and white

Color filters can be useful in b&w photography to control how the world's colors translate into shades of grey. A colored filter lightens similar colors, and darkens colors on the opposite side of the color wheel. The most common filter used for this effect is red, designated #25A in photo jargon. A red filter dramatically darkens blue skies, which can create some striking effects. Orange filters have a less dramatic sky darkening effect. A useful, but subtle, effect can be obtained with a yellow-green filter in landscapes that have a variety of foliage. This filter helps separate the tones produced by slightly different shades of green, so a hillside covered with different trees shows more variation in tonality.

Effects filters

There's a bewildering array of filters for various effects out there; your friendly neighborhood camera store inevitably has a big drawer full of fog filters, sunset filters, multi-image kaleidoscope filters, star filters, soft focus filters, etcetera, so forth, so on, ad infinitum, ad nauseam, yadda yadda, yadda. Fortunately, we don't need to waste much time on these pieces of ka-ka. No filter is a substitute for being in the field when the conditions are right. So much for fog filters and sunset filters. As for cutesy-poo filters, they just don't have a place in the field. If you can't control your impulse to do strange and twisted things to your images, make straight photos in the field, scan them into a computer, and mangle them to your heart's content with PhotoShop.