Originally posted by Pål Jensen I find these threads rather tedious.
You're right insofar as you might feel that these threads are unproductive, broadly speaking. Personally, I find optical technology more interesting than digital, and I find discussing hypothetical scenarios--at the bounds of what my lay mind considers possible--to be more interesting than watching TV. This is purely amusement for me, and you should feel no obligation to participate any more than you should feel obliged to root for the Detroit Lions when they play on some Sundays in fall.
What I really ought to do is go out and buy a basic optics textbook, which will probably require a physics text as well--I think I've about depleted the lay-audience internet sources--and once I have more understanding I should share that with the forum, perhaps, if I'm fortunate, with corrections from more experienced members.
Originally posted by audiobomber There's no point in making a lens that's so large and expensive that no one buys it.
I think it has been established that people will buy very large and very expensive lenses. The question is whether or not producing a very large and very expensive lens would be profitable for Pentax. You conclude that it would not be. That's a perfectly valid opinion, and one nobody here can contradict because we don't have any market data to argue against it.
My view is that a lens with very strong optical qualities, a wide zoom range in the normal region, and top-notch weather sealing would be a viable product. Weather sealing and zoom make for a good combination. The DA*16-50 and DA*50-135 have nearly identical zoom ranges, as do the DA*60-250 and DA17-70. Admittedly, creating a faster or wider-ranged lens with the same optic qualities of these fine lenses would require advances (over the last 3-5 years) in manufacturing non-traditional lens elements or floating optical groups, which may well have occurred but probably hasn't.
A DA*19-80/4 would have essentially the same range as the 60-250 and 17-70, and, upon reflection, that's a perfectly realistic lens specification both in terms of optical technology and product lineup. How much larger or more expensive would it need to be for the lens to be faster or have more range? I don't know. I do know that, if backing off the wide end reduces chromatic aberration at 19mm and increases detail in the 50-60mm range, I'd be excited to put such a lens on my camera. I do know that I'd give strong consideration to using a larger lens if it is faster or has more range, if size, weight and cost are the only penalties for maintaining optical quality.
Many companies have "halo" products that most of their consumers don't buy--but which irrationally affect their decision to buy the product they end up purchasing. I wouldn't be opposed to Pentax creating a unique, big, expensive zoom lens as a halo product to complement their unique, small, expensive prime lenses. But then, I don't have any market data to say whether that would be a sound decision on their part.