Yes, the 24-120 does vary (see the review at:
www.David-Ruether-Photography.com/articles.html, and the
evaluation/samples info at:
www.David-Ruether-Photography.com/slemn.html) - but in the
best samples, except at 24mm (though it is quite
useable at 24mm wide-open), the image is quite
good wide-open (though that is not very wide...;-),
and the flare is low, unlike with the 28-80 which
I also found quite flare-prone... It is possible
that I saw sub-standard samples of both the 28-70
and 28-80 f2.8 Tokinas, though...

On Sun, 3 Nov 2002 23:25:36 +0100, "Klaus Schroiff" wrote:
>
>I agree with you that the lens is RELATIVELY soft at f/2.8. However, I've
>seen mid class Canons and Nikkor such as the 28-135 IS or 24-120 which
>are worse wide-open (remember: same price tag). At f/5.6 the Tokina (my
>sample) is very good indeed though I still miss the 3D touch that I've seen with
>L lenses. The worst issue with Tokinas isn't wide-open performance IMO - it's
>flare in contra light (as bad as Sigmas).
>
>my 2c
>
>Klaus

>> It may depend on test distance and film - at infinity
>> and f2.8, with the sample I tried, with color slide
>> film viewed at 5X and 10X, the 28-80 f2.8 Tokina was good
>> at 28mm over most of the frame, but with soft corners -
>> though not "crisp"; at 50mm, it was soft throughout; at
>> 80mm, it was VERY bad. On color negatives, it looked
>> pretty good throughout at f2.8 shooting distant
>> buildings, though a bit "diffuse" on the trees (more at
>> the long end than the short...).
>> In the past, with Nikkors, I found that some WAs would
>> look sharper in the corners with slide film than with
>> B&W negative film, but the differing results (with
>> the slides looking worse) with the Tokina were
>> surprising. The lens was sharp throughout at f5.6
>> on both negative and positive films, but unacceptable
>> at f2.8 except maybe at 28mm on slide film... Other
>> Tokinas I've tried in the past were very distance-
>> sensitive for sharpness - maybe this one was better
>> at distances others used for testing...(?)
>> David Ruether