Comparing the N24-120, N28-85, N28 f2.8, T28-70 f2.8, S28-70 f2.8

Recently, due to the generosity of a couple of people, I was able
to compare several lenses that included the 28mm focal length.
They were the Nikkor 24-120mm f3.5-4.5, the Nikkor 28-85mm
f3.5-4.5, the 28mm f2.8 AIS, the Tokina 28-70mm f2.6-2.8 AF,
and the Sigma 28-70mm f2.8 AF (non-EX...). All comparisons
were made with the same familiar distant hill-side land/city-scape,
with the same film, but with different developers and different
weather/lighting conditions. I examined the B&W negatives
directly with a good 10X magnifier, making the best comparisons
I could (given the variables) of detail-rendering and crispness
center to corner in the frame. The results, in order of quality:

At 28mm and f2.8 --
- 28mm f2.8 Nikkor AIS (referred to as "P", from here on...) was
sharp and snappy everywhere but the corners, and clearly the
best of all.
- 28-70mm f2.6-2.8 Tokina AF ("T"...) was surprisingly sharp
in the center, and not bad elsewhere, but a bit "diffuse"-looking
away from the center.
- 28-70mm f2.8 Sigma ("S"...) was not very sharp (or very
unsharp...) over most of the frame.
There was a clear 1st, 2nd, 3rd-rate distribution of these lenses
at f2.8.

At 28mm and f4, f5.6 --
- At f4, "P" was again the clear winner, with the Nikkor 24-120mm
f4-5.6 ("N-1"...) next, followed by "T", then the Nikkor 28-85mm
f3.5-4.5 ("N-2"...), and last, "S".
- At f5.6, the differences narrowed among the middle three, though
the order remained the same (with "P" the clear winner, and "S"
clearly last).

At 35mm --
- The order was "N-1", "T", "N-2", "S" - with "T" being
useable-to-good at f2.8 (with slight edge diffusion). The
differences narrow with stopping down, though there is
considerable difference between "N-1" and "S" even at f5.6,
with very little difference between the middle two at f5.6.

At 50mm and 70-85mm --
- The order remains the same, but with "T" more even across the
frame at longer FL's than at shorter at f2.8, and with very little
difference between "N-2" and "T" at f4-5.6 ("N-2" may actually
be slightly better at f4 than "T"...).

Keep in mind that zooms often vary considerably in quality from
sample to sample (especially with wide-range zooms that include
wide-angle in their ranges). The Tokina I tried showed excellent
alignment, the Nikkor 24-120 very slight misalignment, the
Nikkor 28-85 very slight misalignment, and the Sigma showed
moderate misalignment. The construction, finish, and operating
characteristics of all appeared at least adequate and reasonably
pleasant (given the "icky" AF-normal "plastic" construction...),
but the Tokina was beautifully made and finished, with first-rate
feel for MF. It also had a non-rotating front. For a "speed" zoom
(f2.8 is hardly fast...), the Tokina was very good, but the Nikkor
primes in its range are better at all FL's, and often faster. (I
suspect the more limited-range 35-70mm f2.8 Nikkor is also better,
at least at wide stops, best I can recall...) For a wide-range, but
slower, zoom, the Nikkor 24-120 is unbeaten - and even rivals
primes at f8-16. Even so, the Sigma looks good in 4x6" prints,
even in night photos shot wide open...