amorrison
10th of October 2004 (Sun), 13:59
I was trying to decide whether to upgrade to an EF 300 2.8 L lens from my current F4 version but was concerned about whether I could really use the additional aperature due to the smaller depth of field. I put the formulas in an excel spreadsheet and ran the numbers. At about 10 ft, my shooting distance, F4 gives around a 13 mm DOF. Going to F2.8 reduces it to around 9 mm. Sometimes the numbers may surprise you. If you are curious and want to run some numbers of your own, feel free to download it and try it yourself. Please, if you find any mistakes of course, let me know. It's not very elegant, but it gets you the answer. The formulas used came from http://www.wrotniak.net/photo/dof/
File: http://agmorrison.com/pics/lens_DOF.xls
File: http://agmorrison.com/pics/lens_DOF.xls