Monday 4 March 2019

What is a macro lens?


I've read a few threads on here that mention some elementary descriptions of macro lenses and found some marketing fluff in the box for my Canon about them as well, but being a complete novice I was left a bit confused.


Can someone please provide me with a top-to-bottom explanation of what a macro lens does?



Answer



True macro lens gives you a 1:1 magnification -- that is a ratio of size of the subject and its image on the sensor. With 1:1 magnification on APS-C sensor (22×15 mm), you can fill whole picture with area of this size.


Other properties of macro lenses include that they have fixed focal lengths, usually very low distortion (see distortion figures of Canon EF 100mm macro at photozone.de for example). Also, macro lenses tend to have non-rotating and non-moving front elements which is useful since you put them very close to the thing you're shooting.



Mostly due to marketing reasons, term macro is now used for lenses with 1:2 or even lower magnification. (Tamron AF28-200mm F/3.8-5.6 XR Di Aspherical (IF) Macro has 1:4, which means on APS-C body the smallest area you'll focus on is 88×60 mm.)


On compact cameras, macro means "setting where you can focus a bit closer". (Although, as Roddy points out, this can sometimes get you close to actual macro range: Panasonic TZ5 can capture a 63×47mm area, which gives results similar to lens with 1:3 magnification on APS-C DSLR -- image quality aside)


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