It is true that some primes are better than any equivalent zoom, but some of the pro-grade zooms can equal many primes, and even better them. I know from first hand experience that the Nikon 12-24 F4 zoom equals the 24mm F2.8 prime in normal use. By all accounts the Nikon 17-35mm F2.8 zoom at least matches the equivalent primes throughout the zoom and aperture range. And from what I have read, the Nikon 200-400mm AFS F4 zoom is superb. My old Nikon 75-150 F3.5 zoom is very sharp with low distortion and CA.
Where zooms fall down:
Cheaper ones tend to be mediocre at wide apertures, with poor corners.
Cheaper ones have slower maximum apertures.
Most are more susceptible to flare.
Most will have more distortion than a prime.
Most are not as good at close focus as a prime, and most are not so good on extension tubes.
In addition zooms have more elements, and are more complex due to the need to zoom and focus. Hence they tend to suffer more from mis-collimation. The number of brand new zooms that show problems straight out of the box is shocking. Even pro-grade ones have considerable sample variation.
These days manufacturers are putting most effort into designing zooms rather than primes. Most primes are old designs, and some such as the Nikon 28mm F2.8 are decidedly mediocre. So no, you can't simply say that zooms are bette than primes.
That's enough rambling from me.
Back on the ranch ... you didn't say what focal length you were thinking about. Or which brand.
Leif
|