What constitutes a macro lens

Several manufacturers of zoom lenses add macro to the description for example 28-105 mm macro lens this is a little misleading since a true macro lens is 1-1, or life-size meaning that the object will fill the frame of your camera sensor in this instance I have a full frame sensor or FX as its commonly known that is 36 x 24 mm in size. My watch face pictured is very close to that size hence 1-1. Zoom lenses that quote a macro feature are rarely closer than 1-2 of half life size, down to 1-4 a quarter of life size.

A true macro lenses offering 1-1 has enormous drawbacks unless you are photographing on a flat plain (my watch face) there is very little depth of field ( the amount of the image that is actually in focus) at the closest focus distance unless you stop the lens down to f11, f16, or even f32 if the lens will stop down that far. This is why  a ring type flash gun attached to the lens will give superior results. There is in addition the problem that unless you use a focal length of more than 100mm you will be so close to your subject you will either frighten the subject away or worse block out the light with the lens, a lens hood attached will be even worse.

So for most users a zoom or prime lens that will get close enough to allow a final crop of the image to enlarge the subject is usually sufficient and could be said all that is needed in most cases without going to the expense and weight! of a true macro lens.

Life size or 1-1 notice how little of the image is in focus this was at f2.8

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1-2

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1-1 with no cropping the flower head is about the size of a 1 pence piece

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Most smartphone cameras and standard 18-55 kit lenses will achieve this close up of a tulip without cropping

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