Sooner or later, anyone interested in nature photography faces the question: how long a telephoto lens do I need?

Your answer requires that you first carefully consider both your photography and your physical activities. Answering several othewill also help, as you’ll better understand the unfortunate allistops and where your bucks stop.

What do I want to photograph? Do I need top-quality images, or can I settle for acceptably sharp results? How “fast” a lens do I need? How much money do I want to spend?

And – most important for you backpackers and other adventurous types – how heavy is the doggone thing?

If it’s wildlife you want to photograph, you need to consider that most wildlife in Maine comes out to pose in the early morning and late afternoon. A telephoto lens that allows lots of light to reach the film permits you to shoot in such lower-light conditions.

Such lenses are called “fast” because you can use a faster shutter speed. Faster shutter speeds help to produce sharper images, since they offset subject movements and vibrations made by the camera.

The lowest f-stop number – f/2.8, f/4, f/5.6 – a lens opens to describes its speed. An f/2.8 lens is a very fast telephoto lens. An f/4 lens is moderately fast. An f/5.6 lens is a slow lens. Anything slower is a dog.

You can compensate for a slow lens by using a fast film, say 200 ASA instead of 100 ASA film, but you generally pay a price in larger grain and less sharpness with faster films. If your aim is to shoot prints for your walls made from color negative film, you can do quite well with higher-speed films and you can get by shooting with a slower lens.

But if your ambition is to sell pictures to magazines, then you’d better think about it. Slide films are the only choice for most professional nature photographers. That’s because publishers prefer to work with original slides. Since slide film speeds higher than 100 ASA are rarely acceptable, you will often need a faster telephoto lens.

The more light a lens gathers, the more glass it requires to do so. The more glass, the more mass. The more mass, the more cash. And the more gas you’ll need to get it there.

Consider that my Nikkor 400mm f/3.5, considered a fast lens, weighs more than six pounds. The tripod that supports it for sharp pictures weighs 10 pounds. That’s 16 pounds before you even stick a camera body on it.

It’s fun lugging that up to Baxter Peak, but it works for me. It produces very sharp images.

Faster lenses not only weigh more, they cost more. My f/3.5 is only one-half of a stop slower than the f/2.8 400mm lens Nikon makes that costs nearly $2,000 more!

A 400mm- to 500mm-range telephoto lens is about right for most wildlife photography. Longer lenses are heavier to carry, harder to use, and more costly.

If your interest is in photographing people hiking, canoeing, or at other outdoor pursuits, consider getting a short telephoto lens, something in the 200mm range.

A teleconverter can increase the reach of any lens, but you probably won’t be happy with the results of a cheap teleconverter. Teleconverters also take at least a stop of light, making your lens slower.

You can do well with the moderately fast camera-brand telephoto lenses on the market. You can also do quite well with several of the non-camera-brand manufactured lenses that are less costly. Some decent quality slower-speed 400mm lenses are around $500.

Just remember that with telephoto lenses, you get what you pay for. There are always trade-offs. Check the photo magazines for critiques of any lens before you buy.

Once you’ve got your lens, get out in the woods and practice. There’s no better way to improve your photographic skills than to get out there and “go for it.”