Aperture -- Depth of field versus diffraction-limited sharpness

OK, second of three questions regarding testing my new Canon 30D/Ikelite/DS-160 kit.

I was shooting at f/8, 1/125 (Canon 17-85 IS lens in the dedicated 6" dome port) and got a very narrow DOF. I can take this up to f/11 but I start hitting diffraction-limited sharpness issues much past f/8 with this lens.

I was wondering what aperture you folks regularly shoot at as a "baseline".

Thanks,

Dan

Hi Dan,

With an 8 megapixel camera (relates to pixel pitch) I think you can get good results up to about F13

Cheers

James