On 24 Sep 1998 16:29:18 GMT, jsnack@aol.com (Jsnack) wrote:

>>I'm surprised, as I was by a
>>recent trial of a Sigma 28-70 f2.8 - it was quite good...

>Can you elaborate on this, David? Is this the newest version of this lens,
>28-70 EX.

(I should have said, "it was quite good for a medium
range zoom...")
I don't think this was the latest version.
I was so surprised by the first check (under poor
lighting conditions, but I needed to check some other
things quickly that I had put off checking for too long...),
that I checked it again. Roughly, this is what I found:
Compared with a well-aligned 28-85mm f3.5-4.5 Nikkor,
the Sigma showed some misalignment, was subtly less
sharp over most of the frame compared with the Nikkor,
but was actually sharper at the edges, at similar stops.
Compared at 28mm with either the 28mm f2.8 AIS or 28mm f3.5
AI Nikkor, there was no contest - both primes were sharp
over most of the frame wide-open - both zooms required
stopping down to about f8 before they could be considered
sharp (though they were acceptably sharp for non-critical
uses at wider stops) - but by f8, the primes were still
clearly sharper. I don't regard zooms (other than the
best tele zooms) as worth the sharpness trade-off
under most conditions... But the Sigma appears to be
roughly equal in image quality to the Nikkor 28-85.
BTW, there were some other good lenses in this batch:
An old preset Tamron 135mm f2.8 was really excellent;
a 400mm f6.3 Spiratone was very even in sharpness
around the frame, and fairly sharp (this sure beats
cheap mirror lenses!), and an Albinar 80-200 f3.9(?)
was surprisingly good, and easily beat the Nikkor
70-210 f4-5.6 at the edges at the short end, was smaller,
and a stop faster at the long end... (so goes the
"Canonization" of Nikon, with Nikon's less expensive
newer AF lenses... [time was when Nikkors of any price
were generally first-rate optics...]).