Originally posted by wildman and
It seems to me that both of you are laboring under the assumption that
you evaluating objective optical performance when, in fact, you are
making subjective personal economic judgements about the relative worth
of the DA55 compared to the FA50.
My own take on it is that given the numerous and marginal improvements
that Pentax has made to the DA55 over the FA50 and the added production
costs this entails Pentax is probably asking a fair price for the DA55
in purely economic terms. It probably costs Pentax a fair amount just to
get that marginal improvement at f/1.4 in the corners compared to the
FA50 for instance.
The only question is what's it worth to you?
There is no right or wrong answer - just opinion.
I'm sorry, but the differace is not marginal. its extraordinary. When was the last time you saw a lens that was as sharp at 1.4 as the recent best is at 5.6?
You show me any lens that is that sharp in the corners at 1.4. Like every 1.4 50 of its era, the FA50 is not that great at 1.4. If you buy a lens designed to shoot at 1.4 but have to shoot it at 2.0 - 2.8 onwards to get decent results then what have you bought. This is why the F1.7 50 is so popular, its sharp in comparison from the get go, lighter and more economicaly friendly.
At last we have a 1.4 lens we can use from 1.4.
the other problem with the FA is that it simply looks horrible at 1.4. the A 50 1.2 managed to look great even though it was just as unsharp at the same apature.
I am not saying that the DA55 is some kind of miracle worker as it suffers from massive Purple fringing and CA, but there are situations where the 1.4 is far more practical than the FA ever would have been.
As far as AF goes. I'm not certain that the test that was performed has any merit. I know my 50-135mm moves the focus slowly, but when its close to the subject, it focuses quicker than any screwgrive lens I have. SDM vs screwdrive is not a simple matter of measurig how long the throw takes to navigate. it must take into account torque and accuracy. Granted I would like it to focus as quick as possible when moving from one subject to the next, but it might have a lot more to it.
I would like maybee overall impressions how it performs when the focus point is close, does it hunt much, how quickly does it micro adjust. Things which can not be measured easily but have just a high an impact in performance, and in particular sometimes this might make the differance between getting a lock or missing the situation.