I don't agree (1): The major differences between macro lenses and non-macro lenses is that macro lenses have special optical designs which optimize near field usage in the range of 1:1 to 1:10 (approx). They have different OPTICAL designs. It is not just a matter of close focus capability, that can be achieved by putting non-macro lenses on tubes or bellows but they will not perform nearly as well a true macro lenses because just increasing close focus ability without the optical redesign yields mediocre results.....
I don't agree (2): Weve been over this a zillion times, focal length does not directly affect DOF, magnification does. If you use a 100mm or a 105mm at the same magnification (slightly further working distance with the 105mm) the relative DOF will be the same with the 105mm as the 100mm using same aperture setting. JCO -----Original Message----- From: Fred [mailto:[EMAIL PROTECTED] Sent: Saturday, November 13, 2004 9:20 AM To: Tom Reese Subject: Re: A Question About Macro Lenses > The major difference between the macro lenses and the non-macro lenses > is that the macro lenses allow you to focus a lot closer. Agreed. For most of us (who usually would be shooting small and/or close-up 3-dimensional objects, and not just pieces of paper, for example), I suspect that the flat-field characteristic of a macro lens would be less important than the close-focusing ability. > If you're far enough away from your subject that both lenses can focus > then I wouldn't expect to see an appreciable difference in the images > at f/8 or f/11. I would agree. The K 105/2.8 is a pretty sharp lens and the A 100/2.8 Macro certainly is, and their focal lengths are almost the same (so that their depths of field should be very close). Even at f/2.8 or f/4, I would think that the differences would not be large. Fred
