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兼听则明.............
看看J RABIN怎么说这些头的....此人专门玩微距, 微距头一堆......
我把他的原贴拷贝到这来....大家参考一下....
J Rabin12th of July 2005 (Tue), 23:56
Every few weeks I end up reposting this. I've used many macro lenses. All brands are all brutally sharp. Here's the way to think about working distance when these lenses are focused at full 1:1 magnification:
60mm Canon = 10 cm working distance @ $450
100mm Canon = 15 cm working distance @ $480
150mm Sigma = 20 cm working distance @ $620
180mm Canon = 25 cm working distance @ $1,300
180mm Tamron = 26 cm working distance @ $800
The new Canon 60mm EF-S macro is very sharp, a joy to use because of portability and short focal length providing hand holdability. Just keep it in your pocket during trekking. It is NOT a good butterfly/dragonfly hunter because of short working distance. Limited to EF-S mount cameras. If you recall the legendary Nikon 60mm micro Nikkor, this is Canon's equal. Circular aperture blades to about f/5.6 so manually focused portrait OOF areas are nice. It is the only macro lens where you can leave a filter on and still clamp the 24EX macro flash.
You only pay $30 to add 5 cm of working distance from Canon's 60 to Canon 100mm USM macro lens. Unless you need the 60mm for a specific use (I do), the 100mm Canon macro is a better all around value in working distance and flexible use for most people. Due to the floating internal elements, the Canon 100mm has a focal length < 100mm when close focused at 1:1, probably around 80mm, keeping the field of view wider while still getting the 14.9 cm distance.
To step up, you pay additional $140 for the 2nd 5cm distance gained from the Canon 100mm to the new Sigma 150mm. This 20 cm, and the fact the Sigma comes with a hood, tripod mount, HSM auto focus, with full-time manual over ride (I shut off auto focus and manually focus much of the time with macro lenses) makes it an interesting middle contender. This lens is sharp, contrasty, still hand holdable in a pinch. This new Sigma 150mm f/2.8 is very good, if it fits your needs. It is not a me-too offering like many 3rd party macro lenses. I think it will be popular.
Step up on more time, and you pay an additional $700 for the next 5 cm working distance between the Sigma 150mm and the Canon 180mm. This is an amazing optic, almost no diffraction even when stopped down above f/22! Ultimate in working distance. It's big and long and prefers to be used tripod mounted, except when "butterfly hunting."
The Tamron IS NOT AN OPTION even though it is the working distance winner because it's odd filter rotator on the lens front reduces ability to use a macro flash.
What is working distance? Working distance is the distance from the front of lens element to the subject when the lenses are focuused at their closest focus 1:1 magnification. The lenses all focus continuously to infinity also, but we are only calculating close focus distance above.
Calculate Working Distance to subject =
published close focus spec for lens - lens length - distance between rear element and sensor or film plane (which is 4.4 cm for Canon EOS cameras.
Working distance is a BIG limiting use factor (in addition to the full 2 f/stops of light loss @ 1:1 magnification), so get as much as you can afford.
If you're serious about macro, do not buy any macro lens where the barrel length changes during focus. For casual macro users, this is OK (like carrying the old Canon 50mm f/2.5 in a pocket out for a hike).
When we mean macro, we mean life size reproduction, (1:1) magnification or greater. There is loads of fun "close-up" photography at less than life size, say 0.25x to 0.70x (butterfly and dragonfly hunting range) that you can do with diopters, close focusing zooms, etc. A cheap Canon XXmm-300mm zoom with a Canon 500D ($140) +2 diopter makes a good butterfly hunter, providing about 0.4-0.7x depending on focal length.
All macro lenses miss auto focus and "hunt" because the lens elements move greater distances. Live with it.
Hope that helps. J
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