There's no shortage of quality in the 18-55mm and 18-105mm kit zoom lenses that are supplied with current Nikon DSLRs. However, one thing they lack is telephoto reach, so a 'telephoto zoom' is likely to be the first additional lens you buy. Top professional telephoto zooms such as the Nikon 70-200mm f/2.8 VR II will set you back upwards of £1,650.
Thankfully, there are plenty of good-quality alternatives for a quarter of the price or even less. They're certainly not all created equal though, and there are some important factors to bear in mind before reaching for your wallet.
There are two main types of telephoto zoom lens available. Some are designed for full-frame cameras such as the Nikon D700, while others are created specifically for Classic Advanced Photographic System (APS-C) cameras such as the D3100, D5100, D7000 and D300s.
Whereas full-frame cameras have sensors that are the same size as a frame of 35mm film, APS-C sensors are smaller. The upshot is that the image circle produced by an APS-C lens (or what Nikon calls a 'DX' lens) doesn't need to be as large asa full-frame, or 'FX', lens.
With a reduction in the size of the image circle comes the possibility to downsize the physical construction of the lens itself. Therefore, DX lenses are usually smaller and lighter than FX lenses of a similar zoom range.
The Nikon Nikkor AF-S VR 70-300mm f/4.5-5.6G IF-ED, Sigma 70-300mm f/4-5.6 APO DG Macro, Sigma 70-300mm f/4-5.6 DG OS, Tamron AF 70-300mm f/4-5.6 Di LD Macro and Tamron SP 70-300mm f/4-5.6 Di VC USD lenses are full-frame compatible.
Back in the days of 35mm film, 70-300mm was the classic zoom range for non-professional telephoto lenses. Nikon DX-format cameras have a 'focal length multiplier', or 'crop factor', of 1.5x. This means that by multiplying the actual focal length of a lens by 1.5 you'll get the 'effective' focal length of using it on a full-frame camera.
That's why most telephoto zoom lenses designed for APS-C cameras have zoom ranges of about 50-200mm – the zoom range effectively becomes 75-300mm, in keeping with convention.
If you're not fussed about saving size and weight, there's plenty to be said for fitting a full-frame telephoto zoom to your DX-format Nikon. For starters, the classic 70-300mm zoom range gives you an effective 105-450mm, so you get much more telephoto reach at the long end. Also, you'll only be using the central part of the full-frame image circle, where sharpness and all-round optical quality peak. There's also less danger of 'vignetting' (darkened image corners), for the same reason.
One drawback, though, is that at very long effective telephoto lengths of about 450mm, camera-shake becomes an ever-present danger. The rule of thumb is that to avoid it you need a shutter speed that's at least as fast as the reciprocal of the focal length. At450mm, say, you'd need a minimum shutter speed of 1/450 sec (that's 1/500 sec in use).
With a maximum available aperture off/5.6 at the telephoto end of the zoom range, this can be tricky in anything other than bright, sunny conditions without increasing the sensitivity (ISO). That's where image stabilisation comes to the rescue.
Some manufacturers now build sensor-shift image stabilisation into their camera bodies, but Nikon opts for optical stabilisation within the lens, which it calls Vibration Reduction (VR). The system tends to be very effective, especially at long telephoto focal lengths, and many of Nikon's latest VR lenses offer a four-stop advantage.
This means that where you'd need a shutter speed of 1/500 sec to avoid camera-shake, you can shoot at just 1/30 sec and still expect to get sharp, shake-free images with some degree of consistency. Sigma and Tamron have their own, independently developed stabilisation systems.
Yet more choices are to be made when it comes to autofocus motors. Most current Nikon lenses feature AF-S (Silent Wave) ultrasonic autofocus, but there are actually two different types. Basic AF-S features a small ultrasonic motor that drives gearwheels to focus the lens.
The more advanced, ring-type AF-S features two large rings that fit just inside the circumference of the lens, and offers faster, near-silent autofocus performance. What's more, the focus ring doesn't rotate during autofocus, and you also get full-time manual focus override.
Of the lenses tested here, only the Nikon Nikkor AF-S VR 70-300mm f/4.5-5.6G IF-ED and Tamron SP 70-300mm f/4-5.6 Di VC USD have ring-type ultrasonic autofocus. Both of the other Nikon lenses and the Sigma 50-200mm f/4-5.6 DC OS HSM (Hyper Sonic Motor) lens use the more basic form. The remaining lenses are fitted with somewhat noisier standard electric motors.
The Nikon Nikkor AF-S DX VR 55-200mm f/4-5.6G IF-ED, Nikon Nikkor AF-S VR 70-300mm f/4.5-5.6G IF-ED, Sigma 50-200mm f/4-5.6 DC OS HSM and Tamron SP 70-300mm f/4-5.6 Di VC USD lenses use internal focusing. The front element doesn't rotate during focusing, which makes it easier to use rotation-critical filters such as circular polarisers.