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Old Aug 10, 2010, 7:36 PM   #1
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Default how to tel which prime lenses make good macro lenses?

I've learned that not all prime lenses make good macro lenses and most macro lenses are prime lenses, but how does one know whether the prime lense he's buying would make a good macro? Moreover, what makes a macro prime better than a regular prime at taking macro shots?
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Old Aug 10, 2010, 7:42 PM   #2
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all true marco lenses are prime, but not all prime lenses are macro. The fast primes out on the market are ok for close up work, but if you are looking for macro. You will be looking at macro primes. They will say macro. Like the tamron 60mm macro f2, or the sigma 50mm f2.8, and the longer macro like the sigma 105 macro 2.8, tamron 90mm macro 2.8. And the dslr brand you have will have some macros also. I have a canon, and I use the canon ef 100mm 2.8 macro.
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Old Aug 10, 2010, 7:53 PM   #3
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Quote:
Originally Posted by tony pham View Post
I've learned that not all prime lenses make good macro lenses and most macro lenses are prime lenses, but how does one know whether the prime lense he's buying would make a good macro? Moreover, what makes a macro prime better than a regular prime at taking macro shots?
Macro lenses will all be labeled "Macro" ("Micro" in the case of Nikon's lenses.)

What makes a lens "Macro" or not is the magnification ratio. A 1:1 magification ratio is when the lens projects an image onto the sensor that is the same size as the subject. That is, a 1 inch wide subject will be represented with a 1 inch wide image projected onto the image sensor. This all happens before any printing, scaling, cropping or upsampling, either in the camera or in post-processing.

Most "Macro" lenses can do at least 1:1 magnification, some can do even greater magnification, and some can only do 1:2 magnification, where the image projected onto the image sensor is 1/2 the size of the subject. Lenses with magnification ratios of less that 1:2 are not generally considered "Macro" lenses, except in advertising literature.
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Old Aug 10, 2010, 8:20 PM   #4
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A macro (micro) lens is also better corrected for field curvature http://www.slrgear.com/reviews/showp...uct/351/cat/12 and other aberrations then a normal lens.
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Old Aug 12, 2010, 2:58 AM   #5
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So-called "macro zooms" almost always are NOT macro -- they won't approach 1:1 magnification without extension. Some inexpensive 'macro' primes also don't approach 1:1, but have an extensible front element that allows for closer focus. Actual 'macro' primes generally have sharp optics, and as mentioned above, tend-to be flat-field.

There is a class of inexpensive flat-field lenses with sharp optics -- these are ENLARGER lenses. They must be used on bellows or tube extension. As with any lens used for macro shooting, longer focal lengths give a greater working distance. Shorter lenses are good for extreme magnification. Enlarger lenses of 100mm or longer, on bellows, can also be used for general photography.

Many standard primes can be used for macro shooting, but if you don't have extensions with aperture coupling, you need primes with aperture rings. Many standard primes work better for macros when reversed and extended; their working distance will be the register of that lens, often under 50mm. Primes with deep insets at the end aimed at the subject might be difficult to use.

To answer your question, How to tell which primes are good for macros? -- well, there is no easy way. Reversal rings, tubes, and bellows, are all fairly inexpensive. I think it is best just to assemble a macro rig and try out some glass. Using a reversal ring on bellows, or using any lens on extension tubes or bellows, the brand of lens does not matter. I shoot Pentax and have only PK or M42 camera bodies, but I use reversed Canon, Konika, Leica and Minolta lenses on bellows. Try any lens and see if it works for you. Good luck!
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