Originally posted by northcoastgreg I don't have either the 17-70 or the 16-50, but from images I've seen from each lens, it appears to me that the 16-50 has better microcontrast and color rendition. The differences are subtle and some people may not notice. But I would be surprised if they are not there. Nor are those differences "subjective" in the disparaging sense of the word. There are almost certainly differences, even measurable differences, in light transmission and and how that transmission is distributed across the color spectrum between various lenses. Those differences, and additional differences relating to characteristics of the lens that cannot be measured, lead to differences in output which can be noticed by many, if not by most, viewers of images made by the respective lenses, most noticeable in fine color prints.
I've taken many very similar pictures with the DA 12-24, the DA 16-45, and the FA 24-90. I perceive the DA 12-24 and the FA 24-90 as capable producing more aesthetically pleasing color landscapes than the DA 16-45. Is that a "subjective" delusion? Well if it is, it must be a widespread "subjective" delusion, experienced by many people; because while I have sold dozens of images from the 12-24 and the 24-90, I've sold nothing from the DA 16-45. Is that a coincidence? After all, none of my buyers have an idea what sort of lens, or even what brand of camera, I use.
The thing is, I was actually an audiophile. In fact, I still am, but I also used to believe in the exact same reasoning you use for lenses, but applied to audio equipment, cables, etc etc. If you go to Hifi forums, you will also read how people argue that, because everyone describes what they believe to be audible differences in a similar way, the differences almost certainly have to be real.
Nowadays, I'm not so sure anymore. I think that it is equally plausible, if not more so, that the look and feel of the equipment affects the perception of the sound generated by the equipment. Just as the look and feel of really solid lenses could affect perception of images taken with those lenses. So I'm actually not so focused on audio equipment any more, but more on the music itself. I actually find that much more satisfying, because that's what matters.
But I'm no stranger to affected perception myself. So if a certain tweak sounds better to me, then I may go for it, even though I know that it may only be my perception that has changed. The difference is that I'm ok with that.
But getting back to differences in lenses: you say it
appears to you that the 16-50 has better microcontrast and color rendition. That may be the case, or not, but there is no proof here. No A/B comparisons of the same scene, the same light, shot with both lenses in the same timeframe. What is microcontrast, anyway? For the same reason, I'm also unable to answer your question whether it is a coincidence that you sold nothing from the 16-45, but I do wonder if the answer really matters.
I do object to your statement that there are things that can't be measured that still affect image quality. I mean, it's all physics, really. It may be that reviews don't measure certain aspects of lenses, but that doesn't mean that those aspects can't be measured.
Originally posted by northcoastgreg It's not an issue of being offended. Nor is anyone saying you can't write your thoughts. But you made a conjectural statement about matters of fact that I believed to be mistaken and which I thought deserved a response from an alternative point of view. I was not responding to you personally but merely to the thoughts you expressed. Maybe you didn't mean to imply the following, but much of the hostility toward this lens seems to be along the lines of: "This lens doesn't make any sense (for anyone). Why did Pentax waste it's time and precious resources making it?" Just like many high-end lenses, the DA 20-40 is going to make sense for some people, but not for others. Some of the critics of the DA 20-40 don't seem to understand this. They seem annoyed that Pentax should make a high end standard zoom that isn't fast or doesn't have a wide range. But why shouldn't Pentax (and other lens makers, like Sigma) make as many different types of lenses as is economically feasible? I have absolutely no use for an f1.8 standard zoom lens, but I'm sure glad that Sigma decided to make one for the K mount. Neither the Sigma 18-35 nor the DA 20-40 strike me as making the other lens irrelevant. Even though they cover much the same focal range, they are very different lenses for different needs. Isn't it great that Pentaxians will soon have two great new standard zoom options to choose from? So why all the complaining and hand-wringing over the DA 20-40?
I actually don't mind Pentax making this lens. In fact, if it were cheaper, I might even end up buying it. I already have the 70mm Limited, and a small and lightweight set of excellent optics does appeal to me, even if they aren't super-fast. I have actually been considering getting more Limiteds, but don't want to be tied to primes. In that sense, the 20-40mm does make sense to me. Together with the 70 and the 15 it would make a great set. It's just that, for the price, I want it to be a more capable lens, and it's not. At the end of the day, it's still a 2.8-4, and for this kind of money, I know that's going to bother me. That's why I hope they sell none. So they may realize they have to offer more value.
So, in short: I may not have a problem with this lens. I do have a problem with the value that Pentax is offering by pricing this lens as they have. Because I like Pentax to charge what I think are fair prices.
But, if others think this is a fair price for what it is: by all means, go ahead and buy it, shoot with it, enjoy it!