This Ford's chrome grille, "V8" emblem, and colorful paint make an interesting, mildly close-up study with zoom lens set at about 50mm. Photos © Dave Howard, 2000

How many times have you missed a picture opportunity due to not having the right lens on your camera at the time? It never fails: you've just finished taking a wide angle, get-everything-in shot with a 28mm lens; no sooner than you've released pressure on the shutter button, a scruffy old dog wearing a red bandanna meanders into a perfectly framing doorway and pauses. It's got "cover shot" written all over it, and you frantically rummage through your camera bag in search of the appropriate longer lens. Having stayed put as you fumble to match the red dots on camera body and lens, the critter waddles out of the picture the instant before you can get the revised camera/lens combo up to your eye. And, of course, just to add insult to injury, your next photo op will require a wide angle.

After enduring this scenario for the umpteenth time, it occurs to many photographers that a zoom lens would make them "faster on the draw" in the picture-readiness department. They are indeed correct, but many don't research the subject thoroughly enough before purchasing their first zoom. The result can be dissatisfaction, followed by a blanket condemnation of zooms in general. On the other hand, careful consideration of all the factors involved can successfully match a zoom's unique characteristics to your particular shooting requirements.

This old Buick seems to have an art deco persona. Getting in close with a wide-range zoom set to the wide end avoids having to back up with a longer focal length, which would complicate the shot due to the car show crowds parading back and forth between you and your subject.

It should be fairly obvious that the main object of using a zoom lens is to avoid having to constantly change lenses, thereby saving valuable time and missing less pictures of a fleeting nature. Even if the subject itself isn't going anywhere, your own time constraints (tours, impatient family and friends, etc.) can make frequent lens juggling impractical. Besides, on the human nature side of things, if you have to switch lenses often enough, it's easy to lapse into "not-a-big-enough-bang" syndrome, passing up shots on the rationalized justification that it really wasn't that spectacular a shot and therefore not worth changing lenses. That's a bad habit to get into, because I've found that many visually "quieter" shots turn out to be the best frames on the roll, even if it didn't strike me that way at the time.

A few photographers still shy away from zooms because they've heard they're not as sharp as fixed focal length lenses. Thirty years ago that was true, but there's no need to make any excuses for today's better zooms. As with any type of lens, you pretty much get what you pay for, and that goes for zooms, too. However, with modern, computer-aided designs, aspheric and hybrid-aspheric lens elements, low-dispersion glass, etc., sharpness isn't the major concern anymore. So, if even relatively inexpensive after-market zooms are respectably sharp, just what is it you're paying for with the more costly models? To illustrate, let's examine zoom lens characteristics one by one.

Another interest-adding shot made easy with a wide-range zoom. Mrs. Bear looks fashionably attired for a Sunday cruise in her classic '60s convertible. (Tamron SP 28-105mm f/2.8 LD zoom.)

The most obvious feature of a zoom lens is its focal length range. Zooms are made in just about any range imaginable, including wide angle models (17-35mm and 20-40mm), standard short to mild-tele models (24-70mm, 28-80mm, and 28-105mm), and telephoto models (70-210mm, 80-200mm, 60-300mm, and 200-400mm). A more recent and increasingly popular development is the wide-range zoom, covering wide angle to appreciably long focal lengths. Tamron created quite a stir with the introduction of the original 28-200mm several years ago (recently improved and still selling well). No sooner had their competitors introduced 28-200mm models of their own than Tamron upped the ante with a 28-300mm model.

Which brings us to the question, how much range do you actually need? While it may be tempting and seem logical to latch onto the widest millimeter spread available in order to cover any and all eventualities, I would suggest approaching this decision a bit more analytically.

A close-focusing zoom simplifies grabbing colorful details on the fly.

Make an honest assessment of the type(s) of subject matter you normally pursue. Do you consistently careen from wide angle scenic vistas, to close-ups of flowers, to long shots of wildlife or sports action? Then one of the extremely wide-range super zooms may indeed be just the ticket for you. However, many photographers have a more confined roster of subject matter, and therefore would benefit more from a zoom with a range that occupies a particular narrower spread of focal lengths typically required by their subject specialty.

Why not just go with a super wide-range model, comfortable in the knowledge that the seldom-used extremes of the range are there for those rare occasions they're actually needed? Because as good as these super wide-range zooms are, keep in mind that, everything else being equal, the wider the range, the more optical compromises are involved. The various optical aberrations are easier to keep under control with a zoom that is restricted to a particular segment (wide, normal, or tele) of focal lengths. In other words, a 17-35mm zoom only has to deal with wide angle specific design parameters; ditto for "normal" zooms such as a 35-70mm model, or tele-only choices such as a 70-210mm or longer. But modern materials and sophisticated mass-manufacturing techniques continue to minimize the compromises necessary due to focal length range extremes and price point considerations, so don't hesitate to go with a super zoom, but try before you buy whenever possible.

My second, "long" Leica body, equipped with a 90mm lens, made it easy to grab this nearby contrasting shot of the quiet ledge pool with the rushing creek in the background, without the rest of the group I was with having to wait while I changed lenses.

Another approach that I favor whenever reducing your lens load to the absolute minimum isn't mandatory is buying a premium-quality zoom that covers the focal lengths that you use most, and then adding a fixed focal length lens or two to cover the extreme wide and/or tele ends of the range. I feel that this option maximizes flexibility and quality; however, there are times (e.g., when being herded around on an organized tour) when the no-fuss simplicity of one wide-range zoom is worth any and all minor optical compromises involved. OK, that's the third time I've said "compromises" without offering any explanation. The main two factors that are most obvious and that can noticeably affect your pictures are light falloff at the wide angle end of a zoom's range, and a variable maximum aperture that becomes progressively "slower" toward the long end of the range.

The less expensive a lens is, the more likely it will be to exhibit light falloff in the corners of wide angle shots, especially at or near maximum aperture; stopping down a few f/stops helps minimize this effect. As the price goes up, increasing employment of low-dispersion glass and aspherical lens elements dramatically improves the evenness of light distribution at wide angle focal lengths.

All extreme wide-range zooms that I'm aware of have a variable maximum aperture. Most are around f/4.5 or f/5.6 at their longest focal length, which is generally workable. Some with a really long tele end to their range (300mm and more) top out at f/6.3 (which is about the slowest maximum aperture that AF systems can currently work with) or even f/8. On cloudy days, or early or late in the day, f/6.3 results in a less than sparkling bright viewfinder image. Keep in mind that this is "wide-open." Stopping down a couple of f/stops to improve optical performance puts you at f/11-16; add filters and/or tele-converters and a tripod or ISO 800 film becomes mandatory.

That's why I much prefer a premium mid-range zoom with a constant f/2.8 aperture throughout its focal length range. Such lenses exhibit nearly zero falloff at their wide end, the viewfinder screen remains pleasantly bright, and the use of filters and slower films presents few problems. Yes, these premium zooms are considerably larger, heavier, and more costly, but the ease of use and high quality images produced warrant the higher cost and portability penalty.

Another feature to note is the focusing/zooming method, especially with manual focus models. Your choices are "one-touch," whereby you zoom and focus with the same ring, and two-ring models that control each function separately. At first glance, the one-touch method might seem the logical way to go, offering faster operation. However, the most precise way to focus a one-touch, manual-focus zoom is to zoom out to maximum telephoto (to gain maximum magnification), focus, then pull the zoom/focus ring back to the desired focal length. The problem is, that unless you pull absolutely straight back (without twisting the ring either way), you move off the critical focus point that you established, something that's easy to do in hectic shooting situations. Also, some one-touch zooms can creep from the set focal length when aimed up or down while mounted on a tripod. I therefore prefer a two-ring zoom for most of my photography. However, with fast, erratically moving subjects requiring follow focus and follow framing (zooming), a lot of practice with a one-touch zoom is the more time and motion efficient approach. The fact that most people never get that good at manual follow focusing accounts for the current popularity of autofocus cameras.

Be sure to note whether or not the zoom has a rotating or non-rotating front element. Trust me, you don't want a rotating front element; they make use of a polarizing filter and anything other than a round lens shade an impractical nightmare. My 50-250mm Rolleinar zoom, an otherwise fine lens, suffers from this malady and is seldom used because of it. It was my first zoom lens, and I failed to check that feature before I bought it; a lesson learned!

Perhaps a wide zoom range, let's say 28-200mm, appeals to you, but you already have a 28-70mm zoom. You could, of course, sell your current zoom and buy the 28-200mm, but there's another option: buy another zoom that starts where your current one leaves off. In the instance given, you could add a 70-210mm, giving you a 28-210mm range between them. Whether or not this is a good idea depends on what your most-used focal lengths are. If, for example, your two favorite subjects are landscapes and portraits, this two-lens option is entirely feasible; you'd be using the 28-70mm almost exclusively for scenics, while the 70-210mm would be a natural for portraits, indoors or out. On the other hand, if, like many photographers, you tend to have a couple of favorite focal lengths, say 35mm and 90mm, that you regularly apply to the same genre of subject matter (e.g., landscapes), then you'd be constantly switching back and forth between these two zooms, defeating the whole purpose of this exercise. One last possibility is looking for a zoom that partially overlaps your current zoom's range enough to include your most-used focal lengths; otherwise, bite the bullet and buy whatever zoom that would eliminate constant lens changing, except for really extreme focal lengths and special-purpose lenses (fisheyes, PC lenses, etc.). One last consideration for two-zoom outfits: try to make sure they both accept the same size filters (step-up and step-down adapter rings will either vignette at the wide settings, or interfere with attachment of a lens hood).

Incidentally, photojournalists have for decades been using an abbreviated version of the two-zoom scenario, carrying two camera bodies, one fitted with a fixed wide angle, the other with a mild telephoto. Except for Contax's new 35-70mm zoom for their G2, and Leica's Tri-Elmar, this is the only option for rangefinder users.

Then there's the question of OEM (Original Equipment Manufacturer) zooms vs. after-market brands. Back in times BC (Before Computers), the OEM products were most often clearly superior. Today things have changed, and you need to compare similarly-specified lenses between your camera brand and the after-market makers such as Sigma, Tamron, Tokina, Vivitar, etc. Your breadth of choices in AF zooms will depend on your brand of camera. All after-market makers supply their lenses in Canon and Nikon mounts; most also offer Minolta and Pentax versions, but not necessarily with all lenses in their lineups. Each company's (OEM and after-market) "consumer grade" zooms can vary in quality from model to model; there are some thoroughbreds and some mongrels, but generally no "show stock." The premium zooms from both camps include some genuine optical works of art, and, price permitting, these are the ones that will make you a truly happy zoom lens convert (if you aren't already). They tend to be a bit on the heavy side, but not oppressively so.

If you own an older, manual focus camera (as I do), you'll be grateful (as I am) for Tamron's Adaptall-2 interchangeable mount system. It allows you to fit modern glass to hundreds of classic 35mm SLRs, including "orphan" brands whose makers have faded into history. The Tamron lenses illustrated are all Adaptall-2 models; the 28-200mm and SP 28-105mm f/2.8 LD are also available in AF versions.

I welcomed the opportunity to compare Tamron's 28-200mm f/3.8-5.6 LD Aspherical and premium SP 28-105mm f/2.8 LD Aspherical zooms. They both dealt successfully with a wide range of shooting situations. The SP 28-105mm f/2.8 in particular proved extremely versatile in capturing near-macro close-ups of vintage car details under cramped shooting conditions; I can't speak highly enough of this lens' image quality--it is a definite addition to my wish list. If extended reach and lighter weight are crucial, the 28-200mm (or AF 28-300mm) may prove more to your liking. For me, the bright f/2.8 screen image and falloff-free 28mm setting of the SP 28-105mm proved decisive.

So take a long look at the subject matter that you shoot most frequently, and determine the focal length range involved. Then compare features and specifications of zooms available for your camera. Whether it's a AF 24-120mm Nikkor for your Nikon, a EF 35-350mm for your Canon EOS, an APO 50-500mm from Sigma, or one of the previously mentioned Tamrons, you should have little trouble finding a zoom lens tailor-made for your shooting requirements. I have little doubt that you'll miss constantly changing lenses--and, you'll miss less pictures!

For more information, contact Tamron Industries Inc., 125 Schmitt Blvd., Farmingdale, NY 11735; (631) 694-8700; fax: (631) 694-1414; www.tamron.com.