Macro lens question

[jtsull]

Canon makes a 100mm f2.8 macro which seems highly regarded. My question has to do with the aperature of F2.8.
Macros already have razor thin DOF, wouldn't setting the lens at F2.8 make it even more difficult to achieve any kind of DOF? I did try this lens before and needed f10 or more. Why would canon make this an F2.8? Cheaper to make it F4.0 isn't it? :confused_1:

[Igor]

Hi James, in short, macro lens benefits from being fast because MOST macro shooters shoot in Manual mode, not AF, and when you focus manually you definitely need a bright picture in the viewfinder. At f/2.8 (or faster) you'll focus more accurately than at f/4 and slower.

HTH.

[Harv]

Viewing brightness for accurate focus. This lens would also make a reasonable portrait lens with the 2.8 aperture.