In article <4io130$t45@agate.berkeley.edu>, murthy@rice.eecs.berkeley.edu says...
>In article <4imlk0$s41@newsstand.cit.cornell.edu>, d_ruether@hotmail.com
(Bob Neuman) writes:
>|>If you are trying to find differences in quality between the top end
>|>lenses of most makers (those are what are most likely used for the
>|>types of images you are looking at - good photographers rarely choose
>|>to use poor lenses, and will generally select the good ones in a
>|>line) by looking at even very high quality reproduced images (or even
>|>originals), I would agree with you that you will find few notable
>|>differences in quality between lens lines. When you explore the bulk
>|>of a lens maker's output, and especially the lower reaches of the
>|>various lines, you will find differences in overall lens-line quality
>|>that are important to me, but maybe not to everybody.... (Compare
>|>bottom-end Canon zooms with similar Nikkors, for instance....[or even
>|>some of the mid-line lenses, like the 17/18's and 20mm's], and you
>|>may also find differences that can be important to you. While it is
>|>true that the lowest price Nikkor may be more expensive than the
>|>lowest price Canon equivalent in some instances [and even approach
>|>the Canon "L" price, as with the Nikkor 100-300mm or 75-300mm], one
>|>does need to ask the question, "Is a mediocre lens a good buy at any
>|>price?").

>Well this seems to come up again and again on this forum but I don't
>think that there is any evidence of it.

At least in the case of the Canon 75-300/100-300, there have been plenty
of comments about their limitations, espesially at the long end. The
Nikkor equivalents that I have used are mighty fine at 300mm, even
wide-open.

>Are you suggesting that Nikon's 28-xxx zooms perform better than
>Canon's? Every lens test I have seen ranks most of the mid-priced
>Canon zooms (28-105 ($330), 28-80 mk I, 28-70 II) as highly or even
>more highly than their counterparts from other manufacturers,
>including Nikon.

No, but I'd rather believe user comments on their own experiences
with particular lenses than the "test reports", which I find often
faulty when it comes to lenses that I know well, often in multiple
samples (see "SLE[MN]" at:
http://www.cs.hks.se/~nicke/private/photo/david.html OR:
http://f-server.cs.hks.se/~nicke/private/photo/lenstest/
under D.R.'s Subjective.... for an idea of the extent of my
experience with Nikkors).

>In addition, Canon's budget 20-35 is praised by most people.

You may not have noticed negative comments in a recent thread......

>Don't confuse marketing with ability. Canon might purposely
>put out a crappy 35-80 lens on the low end but the point here is
>whether some manufacturers have coating technology that others don't.
>I don't think that is the case that's all.

I agree - though Nikon tends not to put out optically "crappy"
lenses at any price, but apparently Canon does.....

>In fact Canon has quite a few lenses that get better ratings than
>equivalent Nikkors (with the Canons being mostly cheaper) if tests are
>to be believed. Let's take the mid-priced lenses (since nobody who is
>halfway serious would buy the cheapest lenses there are.)

Why not? They have the advantages of being cheap, and often unusually
light - and if they are optically good, they are a real bargain.

>Canon's 70-210 ($300) gets very high marks according to fotomagazin
>(9.6!!). Canon's 75-300 and 100-300 ($240,$300) are both better
>performers than the Nikkor 75-300 according to fotomagazin (8.8
>versus 8.4), according to George Lepp, and the British mag Practical
>Photography ( and they are all a tad worse than the Sigma 75-300 APO).
>However the Nikkor 75-300 costs the same the 100-300L Canon and the L
>Canon is quite superior to it in performance.

Sorry, your quotes may be correct, but I do not believe the conclusions.
Haven't you seen the many negative comments here on the performance of
the "top" Sigma? And on the Canons? I have owned several 100-300mm
Nikkors and one 75-300mm Nikkor, and they were all sharp to the corners
wide-open throughout the zoom range, contrasty, very low in distortion,
low in flare, mechanically sturdy lenses - performance that is darn
hard to equal, let alone surpass. And from user comments here, it
appears that the similar non-Nikkors you name (except, maybe, the "L"
lens) have some obvious optical deficiencies, particularly at (the most
useful) long end.

>I have seen side-by-side shots from the Canon 35-135 and Nikon
>35-70/2.8 and couldn't find that one was any inferior (at moderate
>enlargements of-course). Similarly, most Canon primes (20,24,28,...)
>get high marks for performance, especially the 24 and 85/1.8. These
>are not "high end" lenses.

I think I said about the same thing earlier, so I am not going to
disagree with the above, except to note that it requires somewhat
more "cherry picking" in the Canon line to avoid the lesser lenses
than it does in the Nikon line, from what I have seen, simply because
there are fewer marginal lenses in the Nikon line.

>I don't doubt that there could be lens to lens differences;
>for example, Canons 28/2.8 gets 4 stars from Chasseur d'images while
>Nikon's only gets 3 (OTOH, the nikkon 35 gets 4 stars versus Canon's 3
>stars)

You have named (if it was the 28mm f2.8 AF non-D Nikkor) one of the
very few lenses in the current Nikon lens line-up that is, in my
opinion, not worth owning (but try the AIS 28mm f2.8 for truly
excellent performance - Nikon does give you alternatives....).

>but to claim that one manufacturer has some magic coating formula that
>works well everywhere doesn't hold up when one looks at tests and
>testimony from users who have used both systems.

Hmmm, I don't believe I ever claimed that (Heck, I don't believe
all that much in the advantages of multicoating!). What I did say
originally was that a local photographer who switched from Canon
to Nikon commented on the overall higher contrast of the Nikkors
compared with the similar Canons he owned. (BTW, I have seen this
same comment elsewhere.) If you like Canon lenses (or Minolta,
Pentax, Sigma, or whatever), use them! Don't worry about which line is
best (unless you really care, in which case, buy Nikkors! ;-) ;-) ;-).
Hope This Helps