Macro lenses

[Outhouse]

How do these differ from normal lenses?

[shoturtle]

They are design to do extremely close focus for one. They tend to be very sharp lenses, as you need to stop down to combat shallow dof. So they are very good even at f20.

We are talking about true macro lenses correct?

[PeterP]

yes, true macro lenses reach at least 1:1 magnification and some go to 5:1 like the canon mp-e 65mm
they are also highly corrected to produce a flat field low distortion image.

http://www.bobatkins.com/photography...ro_lenses.html

[TCav]

Aside from the close focusing, sharpness, and little field curvature, none of which adversely affect conventional photographic purposes, macro lenses are also very slow to focus, either automatically or manually. The focus mechanisms used in macro lenses are geared differently from those in conventional lenses. They give the photographer (or the AF system) more room to make minor adjustments to the focus.

While this is fine and desireably for macro lenses, it can make conventional photography more difficult and cumbersome.

[tclune]

Originally Posted by TCav

Aside from the close focusing, sharpness, and little field curvature, none of which adversely affect conventional photographic purposes...

I often wonder if that's true. I would expect that the traditional focus-then-frame approach would be more inaccurate on a flat field than on a traditional concave focusing plane, because a concave field would at least partially compensate for the rotation on reframing. But I don't know that for a fact.

[PeterP]

Bottom line is they are designed primarily for use as macro lenses.

Other uses where they might work are incidental niceties. They do make good portrait lenses at least in controlled studio situations.

If you have little or no interest in macro work, I would not be buying a dedicated macro lens. Standard lenses of the same focal length and aperture tend to be less expensive and as mentioned faster operating.

Also a standard lens with inexpensive extension tubes or a dioptre filter in front can do some reasonable macro work.

[TCav]

Originally Posted by PeterP

Also a [conventional] lens with inexpensive extension tubes or a dioptre filter in front can do some reasonable macro work.

... presuming that you're starting with a good conventional lens. If you're not, extention tubes and/or closeup filters will magnify the flaws you're starting out with.

[PeterP]

Agreed!
GiGo principal applies.

[BillDrew]

Macro seems to be applied to any lens that can get to 1:4 or better.

[PeterP]

Yes, but that is the marketing department for you.

Originally Posted by BillDrew

Macro seems to be applied to any lens that can get to 1:4 or better.