[Nicolas06]

Actually it's 25% of original resolution - if you cut an image that is half of width and half of height of original you get only 25% or original resolution since you multiply both edges (0.5 * 0.5 = 0.25). So in K3 24MP sensor the resulting image is 6MP not 12MP.

What we call MP is divided by 4, it is the surface let say it's unit would be pixel^2. But when we use lw/lp, we mesure it in one direction at a time, and so it only get 50%...

[voy-tech]

What we call MP is divided by 4, it is the surface let say it's unit would be pixel^2. But when we use lw/lp, we mesure it in one direction at a time, and so it only get 50%...

True, i was thinking about the resulting image resolution in MPix, since someone could think that a 50% crop from a 16 MPix sensor will give 8MPix image (still quite usable for prints), when it will only give a 4MPix image (not so much usable anymore - for me the borderline is around 6MPix).

[Nicolas06]

What I'm not seeing is evidence that any other lens would do a lot better, or that it matters, especially in web sized images. While a regularly change to the DA-60-250 if I think I might want to print a picture. I would happily have shown a picture taken with 77, but I don't have one. My point in showing that picture was not to show how bad the 18-135 is, I have worse lenses, but to show how little difference it makes in everyday images. Looks bad pixel peeping, looks fine web sized.

If you crop 50% of your pixel width and hieght, you crop 50% of your resolution. It's pretty insane to be talking about the loss in resolution between a DA 18-135 and a 77 when you're never going to use even a fraction of that resolution in the first place. IN the world of 12 MP camera that wasn't as true, in the world of 24 MP cameras, if you're shooting with a lens that scores excellent on the lw/ph measurements, as the DA 18-135 does, you're not going to have issues. If you would like to quote a real world example of where I'm wrong, I'll be happy to listen. As I said, if you loved the 77 on your K-10d, you'll love the 18-135 on your K-3, and you'll get better resolution from it. If you want to pick on it. pick on the CA levels which are going on mess up your micro-contrast. That's the big issue between Pentax zooms and cheaper Pentax primes.

Actually I never said that the resolution would be better if I crop my pictures... or that I need the 24MP of my FA77 or 18-135... for me the main use of such high resolution is more cropping capabilities, and this is what we speak of.

77mm cropped to 135mm is 8MP. 85mm cropped to 135 is 9.5MP. This is more than enough for most uses. As we agree we don't use all theses extra lw/lp. So the 16-85 could handle pretty well 135mm framing and will get you 16mm too... That's not that bad.

As per FA77 vs 18-135, the question is not the resolution the question is what lens render better colors, contrast, micro contrast, out of focus transistion, hability to make the subject pop...

Something basically like that (here framed 77mm).




This is not a question of resolution. You see it at web size, even through it pop more in full screen than a small thumbail. This is not a question of apperture. This is f/4.5 here, not so different than what the 18-135 would do at same focal length. This is the hand, the nose, the subject seems to pop. It look quite sharp but this is only 1024x768... something that can have no more 560 lw/lp. Something that is 0.7MP. It look sharp not because we have 24MP sensor and we may have 3000+ lw/lp in the center. It look sharp because of the micro constrast. It pop because the colors are punchy.

If you click on it and go for a higher version to see it full screen it is even far better. No need for more than the 1362x2048 shoot, not even 3MP and no more than 1100 lw/lp.

That why one would go for such lens. And that why I said that the picture even cropped would still look better. You are right: the extra resolution is useless except for 30" or bigger prints... but it allow to crop. And the other characteristics of a lens, it rendering, it ability to make things pop, how it reproduce colors... All of this is directly visible.

But as far as we are concerned, I doubt even 16-85 to provide such feature... This is just 85 with a 24MP sensor... That enough to crop up to 135mm and keep 9.5MP worth of resolution. And that was my initial point.