Originally Posted By: taym
Originally Posted By: DWallach
On the flip side, the 100mm will have less depth of field at the same aperture. Advantage goes to the 50mm.

And, I take this is a disadvantage because in order to increase DoF you need to decrease aperture and therefore you will need more light/longer exposure time, all else being constant. Am I correct?

Yup, that's exactly the idea. Of course, when you're using a macro flash kit (e.g., a ring light or the Nikon R1C1 kit), guide numbers are largely irrelevant because you're so close to your subject. You can bring as much light to the party as you want. If you want to work with available light, however, this is a significant difference.

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But, I suppose that sharpness or detail level will not be affected directly by this, as they mostly depend on the optics quality?

When you're buying a macro lens, you're paying for optical quality.

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So theoretically, at a given magnification level, a Macro lens will produce sharper / more detailed images than a "standard" lens, again holding all else constant: lens build quality, etc.

Pretty much, yeah. Or, if you prefer to think of it as what you get for a fixed pot of money, you're trading off a wider maximum aperture for increased sharpness and a focus knob that racks the lens out a bit further. (For what it's worth, according to Thom Hogan, vibration reduction doesn't have much impact when you're doing super-duper closeups, so you may be able to save money by buying a cheaper macro lens without it.)