I'd have to dig through my archives to find it, but Popular
Photography here in the U.S. published a report about AF focusing
accuracy a number of years ago. The results were less than pretty. I
wrote Jason Schneider a while back suggesting they run tests on
current models, but I wouldn't be surprised if their advertisers
raised hell after the first article and Pop is gun shy now.
They published 'real life' in camera metering tests a couple of times
with similarly ugly results and we haven't seen one of those recently
either.
FWIW/ScottGee1
On 9/28/05, Winsor Crosby <wincros@xxxxxxxxxxx> wrote:
>
> Both Canon and to a lesser extent Nikon still have problems with AF.
>
> AF has gotten better in some ways but is incredibly complicated as I
> understand it. Some cameras have a dozen or so AF points that provide
> data and some sort of complicated algorithm is needed to select among
> them and hopefully it will be the one you wanted. Not only that it
> has to be able to gauge a changing focus for moving objects and
> predict where they will be when the shutter operates.
>
> No one wants the old fashioned AF that hunted back and forth for the
> sharpest image. Might as well do it yourself. Now the little computer
> inside has to gauge, even on a stationary object, how quickly the
> contrast is improving as the focus is begun and taking into account
> the depth of field of the lens makes a guess as to where the point of
> sharpest focus is going to be, and taking into account the momentum
> of things shuts off the focus motor so that things will coast to
> sharpest point of focus. Amazing it is ever hit accurately, but does
> pretty well most of the time. More of a problem now with smaller
> viewfinders without focusing aids to touch things up.
>
> I think your analysis of glass quality is spot on. Nikon posts a MTF
> chart for most of their lenses on their Japanese site as does Canon.
> Nikon like most makers has a few legendary single focal length
> lenses. Even those best ones are significantly bettered by the curves
> for even some of the less expensive recently designed zoom lenses.
> Plus digital with its ISO flexibility has lessened the need for some
> specialized single focal length lenses like the very expensive and
> superfast lenses, especially the ones that don't really hit their
> stride until stopped down a bit. :-)
>
> From the marketing point of view and the perception of quality and
> price it probably makes more sense to sell one zoom to more customers
> than several single focal lengths with a smaller margin and less
> economy of scale in the manufacturing. If you make a 28, 35, 50, 80
> and 100, you will sell the 50 that came on the camera with its small
> margin and maybe 1 or two others to a smaller percentage of your
> camera buyers. The same percentage on a more expensive zoom to almost
> every person that buys your camera is a lot better financially.
>
> Still those slightly softer, faster, smaller lenses with their
> shallow depth of field and pretty bokeh seem pretty nice in
> retrospect. And how I miss moderately wide angle lenses with little
> or no barrel distortion.
>
>
>
>
>
>
> Winsor
> Long Beach, California, USA
>
>
>
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