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[OM] Re: A little bit more Tokina/Zuiko testing

Subject: [OM] Re: A little bit more Tokina/Zuiko testing
From: Moose <olymoose@xxxxxxxxx>
Date: Sun, 04 Jun 2006 00:53:56 -0700
Chuck Norcutt wrote:
> .....
> This was a very brief test using only the Zuiko 35/2.8 at 2.8 and the 
> Tokina 28-80/2.8 at 35mm and 2.8.  I took both autofocus and manual 
> focus shots with the Tokina.
>
> ..........  But 
> in the relevant range that's in focus the Tokina zoom is the very clear 
> winner.  I guess 30 years of lens development has to be worth something.
>   
One thing I have noticed in tests of recent zoom lenses using multiple 
special dispersion and aspheric elements is that the old pattern of 
image sharpness starting off softer at maximum aperture, improving 
through a middle, optimum aperture, then generally declining some or a 
lot at smallest apertures is not true of these new designs.

Many of them seem, at least at some fls, to be as sharp wide open as at 
f8-16. Again, I'm just browsing through published tests, not testing 
them myself. The implications are interesting, and I haven't heard much 
said about them. In the old days, one assumed that a 300/4.5, for 
example, would not reach maximum performance until f8 or f11, as Gary's 
tests show. Then a zoom which goes to 300 mm, but only at f6.3 might 
not, in the old days, be expected to reach optimum performance until 
maybe f16-22. However, tests show some such achieving optimum 
performance at f6.3-f8.

Anyway, that digression about the long end aside, I would expect a 
modern, pro level zoom to outperform most primes when both are wide 
open. I would also expect the difference to narrow as they are stopped 
down, although I wouldn't be surprised to see the zoom continue to come 
out on top.

I know lots of people want a wide range of primes optimized for digital 
sensors and assume manufacturers are largely not providing them for 
marketing and profit reasons. I propose it is possible that   it may 
also in many cases be because they can't see that they can exceed the 
performance of their latest zoom designs, except perhaps at uneconomic cost.

Moose

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