Use DOFMaster to calculate the depth of field in your photographs. You'll be able to select the lens and f/stop combination that provides the zone of sharpness you need. Use it to calculate the hyperfocal distance for landscape photography.

Depth of Field Table:

http://www.dofmaster.com/doftable.html

DOFMaster Web Application for iPhone and iPod Touch:

Open http://iphone.dofmaster.com on your iPhone or iPod Touch to use the web app.

Depth of Field Calculator:

http://www.dofmaster.com/dofjs.html