F stop for landscapes w/ em-5

Whether or not diffraction is a problem at any given f-stop depends a lot on how large the image display will be, whether on screen or in a print.  For example, on a recent trip I used f/8 a lot with the Pan 14-45, which is sharper at f/5.6.  On screen at 100% I can see slight softening, but viewing the entire image at 9.5" wide it's only at 20%.  In this case, and in an 8x10ish print, the image compression eliminates the softness.  Everything looks sharp as a tack.  With a large print (a 16mg file makes an 18x23" print at 200 dpi), it would normally be viewed from further away, which again, negates the issue.  This is one of those cases where there can be a big gap between theory and practical reality.

In landscape work DOF is the most important thing.  I use whatever aperture is required for the scene.  I don't make giant prints, so I don't worry about diffraction.  What good does it do to limit the f-stop for diffraction purposes if the resulting DOF isn't enough?

How to know what aperture to use?  I use a hyperfocal distance chart.  This link contains a set of charts for 4:3 at a range of focal lengths from 12mm to 150mm, and instructions on how to use it

http://cjcom.net/articles/hyperfoc.htm

The chart is about half way down the page, and there's also a link to download a file for printing.  I carry a copy in my camera bag.

With 4:3 sensors f/8 is usually enough for even the most extreme scene.  For example, with a 20mm lens f/8 delivers 6 ft to infinity when focused at 11 ft, and at 14mm it's 2.8 ft to infinity.

Regards,
Clayton

Info on black and white digital printing at  
http://www.cjcom.net/digiprnarts.htm
I-Trak 3.0   http://www.cjcom.net/itrak.htm