I also agree that it would be a lot more helpful if all lenses were tested at the same effective aperture numbers. I believe that photodo's global numeric results all referred to f4 and f8? This is of course more convenient for comparison than tests at wide open and two stops down. Still, even with the latter method it is not so difficult to understand, that a f2.8 zoom lens with 70 points for its performance at f2.8 and f5.6 is better than a f4 zoom lens with 70 points for its performance at f4 and f8..... Taking this into account, the FA*28-70/f2.8 and the FA*80-200/f2.8 clearly are Pentax's best zoom lenses according to CF testing. Thus I would not say that CF's lens tests produce ridiculous results.
Arnold
Alin Flaider schrieb:
Arnold wrote:
AS> comparable. In their test reports they clearly state that the results AS> for lenses of different speeds cannot be compared directly.
Really Arnold, then what good are these results for!? After all,
people are more likely to decide between different lenses of the
same brand, rather then between similar offering of P and C!
Moreover, knowing very well how a lens performs they want to
see where another one stands relative to their own reference.
I'm afraid CF results suffer from the same syndrome Photodo once
did. These global numeric results quantify too many factors to be
meaningful. I'd rather stick to the MTF charts - there I can see the
contrast and resolution on center and edges at various apertures, I
can even get an idea of the boke (!).
Indeed the MTF allows me to make a direct comparison between
28-70/4 and 200/2.8. Once I decide over the optical output I can then
take into account speed, focal length, size, price, etc.
I do understand that MTFs are harder to digest by most readers,
but then these can be translated in simpler terms without
necessarily resorting to overall figures that lend themselves easily
to meaningless comparisons.
Servus, Alin
AS> Also one AS> must take into account, that for a super wide angle zoom like the AS> FA20-35/f4 a good performance is harder to achievbe than for a zoom like AS> the FA28-70/f4, so 70 points for the 20-35 is much more of an AS> achievement than 69 points for the 28-70/f4. Also, a zoom with larger AS> zooming range usually does not perform as well as a zoom with smaller AS> zooming range.
