[genewch]

Suppose there are a 100mm macro lens and a 100mm ordinary tele lens. Both use the same aperture and take pics for an object at the same position (eg 5m away). Do they produce the same depths of field, or the macro lens produces a shorter DOF? Why?

[APO-BIOGON]

Same DOF.因為Focal length、Aperture 和Distantce 都一樣。除了以上三?其它Factors 不影響DOF例如是甚麼鏡頭 Plannar, Tessar, Biogon.

[genewch]

Thank you. If the lens design is not related to the DOF, does it mean that a tele macro lens can provide more advantage because I can use it for far away objects as well as very closeups? I saw some comments that people use a Canon 180mm macro for ordinary tele use. I even thought of this use. So does a macro lens perform the same as an ordinary lens (AF speed and aperture probably not as good as an ordinary lens)?

[kkyy]

Gene,

I think you already know the answer. Don't underestimate the "slowness" of Macro lens' AF, it can be real pain. For stationary subject it can be fine. For moving subjects like on stage as you want to use it for, you won't have much luck with Macro lens used as fast tele.

There is the other side of argument, the 180 3.5 is insanely expensive. You can put a set of cheapy Kenko ext tubes in your pocket and transform a tele into Macro lens too.

I have compare the 135 2L and the Sigma 150 Macro in terms of bokeh and Macro ability, will PM to you for comparison.

kkyy

[genewch]

A macro lens is of course designed for closeups with high magnification. But for photographing far away objects (even at infinity distance), does it perform not as good as a regular tele lens, say 100mm macro vs 100mm regular? I heard of that but I don't know whether it's true.