[howieb101]

Well the Nikon D800's are all using a Bayer Sony sensor so the Pentax ff camera output is likelying going to be similar.

To throw a spanner into the discussion a Sigma SD1 Merrill should output excellent landscapes with unique Foveon output that is arguably better than what a Bayer sensor is going to give you.

I am seriously considering a SD1 for something different rather than the ff although that is probably somewhere in my future as well.

Howie Be

[Nicolas06]

So basically with a 16-50 sdm shooting landscapes what would be the optimum f stop in your opinion based on past experience ??

osv like to throw absolute things and to me there also a difference between diffraction and the optimum for a lens design. Some lenses are better at f/4, most at f/5.6 and f/8 allow to often get better borders.

And from reviews looking at your 16-50 it seems to perform better at f/5.6 at 16mm but perform better at f/8 at 50mm. Anyway the difference between f/5.6 and f/8 is not big enough to bypass more important aspects like what apperture would give the best results artistically. If f/8 (or even f/11) help you get a long exposure shoot or get more deph of field, then so be it. If f/5.6 or even wider apperture allow you to keep more speed handled, then so be it.

From a pratical point of view on a K5 you have a bit of diffraction starting with f/11 but that's not really key. If you need f/11 for the deph of field, you should go for it. For f/8 to be really an issue diffraction wise would need a 50MP sensor.

From practical purpose if really ultimate sharpness was your objective, you would take shoot at a longer focal length and stich many together using a pano head. With this technique, even gigapixels worth of detail is possible. If you want to display your landscape shoot on a full wall with very high level of detail, this is not the mere 36MP of a D800 that will make the difference. You'll want 100, 200, 500MP !