Thank you Joseph. Your tests cured my zoom-phobia. I have always thought that the since 28-105 PZ has an excellent reputation as a very sharp lens but it still wasn't sharp enough when compared to any of my primes, I have to stick with prime lenses only. Turns out I was very wrong indeed.
REPLY: It is being said that todays best zooms are every bit as good as primes. You can find it even in several photo books like the ones by John Shaw (who in earlier books only recommended primes), Charles Campbell etc. I would modified it to todays best zooms are better than yesterdays primes and this is valid to the extent generalizations go. E.g. the FA645 45-85/4.5 lens is significantly sharper than the FA645 45/2.8 lens.The zoom is also much better when it comes to flare, in contrast to what would expect. The FA* 28-70/2.8 is sharper than the A 35/2.8 and I'm sure some of the better wide angle zooms are sharper than my A 24/2.8. The better telephoto zooms are now so good that they have virtually conquered the whole short telephoto market. Zooms will generally show more distortion than primes highly corrected for such. It is still true that the best primes are better than the best zooms but such prime lenses are far between. Interestingly, I increasingly find that zoom lenses seem to have better all round qualities as compromises seem to be evenly distributed. Many modern primes are in comparison often quite specialized optics where certain usages may have defined to a large extent the compromises made. Then theres the trade-off between resolution, accutance and contrast. So there really are no clear cut answer. It is much like Prova F vs. Kodachrome. Apart from the color palette differences, the Provia resolve more than the Kodachrome but the images appear less sharp. John Shaw says that no one can pick his shots from from zooms from the the ones from primes on the light table. This, toghether with their flexibility, explains their domination in increasingly larger parts of the focal lenght ranges. Simply put, the best zooms today are so sharp quality vs. primes is mostly an academic excercise. If a good zoom has the speed you want and don't distort unacceptably for your subjects, there aren't many reasons to avoid them anymore on otical criterias something most photographers have discovered judging from the zoom sales volume. BTW I've been a prime only person until last year but I still use primes for 35mm because the Limited lenses are sharper than any zoom. However, I admit that good zooms are good enough and that the differences for many will be academic. At least, in order to spot it you need to use the best of techniques. Pål
