Some new lenses

most people could get away with 6mp and would NEVER see any difference other than hearing a sales clerk tell them "This has more megapixels, so it's better"

There are very few lenses that can outresolve the "benchmark lens" (Zeiss Planar T* 50mm f/1.4 ZF) the original release date for the Planar was 1896 so producing a better lens is very unlikely, although it has been done a handful of times, we've hit the physical limitation for lens resolution and therefore adding more resolution to the sensor is pointless, it will only reveal the limitations of the lens in use.

John

Apparently there's a lot of EOS 7D owners chasing FA Ltd's

John

The Zeiss ZM-Biogon 25mm ƒ/2.8 T* lens was supposed to be the
sharpest link

Maybe so, The FA-43 Ltd. FA-31 Ltd and FA-35/2 on the K10D all outresolve the Planar on the Nikon D200, both 10MP cameras. I'm only saying the Planar is the benchmark they use. There are only a handful of lenses thet outresolve the Planar at f/4.

John

Now I am perplexed.

The resolution numbers as tested are not necessarily up to the expected levels and yet these lens are regarded as the zenith of resolution performance?

I thought we were dealing with science here? How come we dont have a standard that can be reliable measured? Is there a way of saying definatively that lens X is 20% sharper than lens Y at a given aperture or lens Z has 12% better resolution than lens Q ?

Surely sharpness contrast and resolution can be quantified.

I accept that lens have "character" and this will be the main reason why I and many others would purchase- but this is subjective choice and certainly cannot be properly measured

Well the lenses do score very well on this and other tests. The controversy seems to be that the epz test doesn't quite agree with some of the other reviews in some cases. Maybe this is down to copy variability (the FA samples were second hand) or maybe, heavens forbid, a testing error!

I for one do not dispute the test findings in general, which seem quite in accordance with previous tests and images from the lenses. It is only the rather odd finding of exceedingly low MTF50 in the corners of the FA43 that seems out of kilter. I would not expect this to be so bad when stopped down.

MTF tests are very useful, especially those Leica and others publish, which show sagittal and meridonial measurements. The relationship between these can even predict how pleasing the bokeh might be. If all manufacturers were as open in providing these, it would be great aid to intelligent buying decisions.

Comparing across systems is even more impossible than comparing across sensors in the same system.

To be clear the FA 50/2.8 macro is likely the sharpest Pentax lens from f/2.8 to f/4 (according to Yoshihiko), equalled at f/5.6 by the FA43. Of all the lenses tested for the K10D by Photozone the FA43 is tops. But there's little point in arguing a few points one way or another when so many other factors are equally if not more important.

The trouble is that manufacturers often don't explain what their lenses are designed for. If you read an M series Lenses and Accessories booklet, almost every lens listed is "the most versatile in the range" and it's meaningless.

If a lens is a portrait lens, softer wide open but sharp when stopped down, then saying so avoids disappointment. If we want a lens that's critically sharp wide open it will be a quite different design to the portrait lens.

But read the Leica literature and they actually discuss the weaknesses of different lenses and the compromises of using the cheaper ones compared to the more expensive and (we assume) better designed. It's terribly refreshing!

That's good, but cheaper doesn't always mean worse.

For example, a 400mm f5.6 lens will be cheaper than a 400mm f2.8, but might even be optically better.

Maybe they liked the idea of having a full range of own brand lenses from ultra wide to super telephoto with excellent flash systems and good manufacturer support when needed?

Maybe not?

Best regards

K10D, I don't get your point and assume you are misreading mine.