Autofocus for macro? Perhaps if your eyes are so bad manual focus is impossible but it's just not possible to do "serious" macro with AF due to DoF being so limited and half of the DoF being infront of the point of focus.....AF tends to lock onto the nearest part of a subject so you waste half of your DoF if you use AF.
By serious macro I mean carefully controlled DoF used for differential focus effects, typically shooting at less than 1:1 magnification to get the required DoF. True macro is shooting at 1:1 or greater.
As for using wide angles and tubes to shoot roses and long lenses having less DoF.....makes no odds other than angle of view and working distance. At any given magnification and (effective) aperture DoF is the same regardless of focal length. E.g. you can get 35mm and 200mm lenses that will both focus close enough to give 1:1 magnification and both will give the same DoF. Increasing magnification reduces DoF (which is why I expect the 300mm on bellows gave limited DoF).
__________________
Andrew - My pics on Flickr
Canon 7D, 24mm f/2.8, 50mm f/1.4, MP-E 65mm macro, TS-E 90mm, 100mm macro
Last edited by daft_biker; 07-23-2008 at 02:09 PM.
|