I don't think there is. But from John Shaw's "Closeups in Nature":
"Let me give a broad definition of a "macro" lens as the term is normally
used. A macro lens close focuses all by itself. That's all there is to it. A
macro does not have any special properties except for its ability to close
focus without adding any accessories. It is true that macros are optically
optimized for maximum sharpness and flatness of field in the closeup range,
but in practical field terms, all lenses will work fine for closeups if your
photographic technique is good.
. . . . .
Macro lenses are more corrected for flat-field reproduction than normal
lenses. If you're planning to do document copy work, then by all means
invest in a macro lens. However, for normal field photography, this feature
is not particularly advantageous. Outdoors you generally don't shoot
anything that fills the frame, edge to edge, in a flat field.
A macro lens does not make a closeup or any photo shot with it look
different. The focal length of the lens used, and only the focal length,
determines the "look" of a photo. Why then even consider buying a macro? The
answer is simple: convenience. You won't have to add or remove tubes for
many closeup subjects. The range of photographic subjects between infinity
focus and 1/2X is staggering.
I've heard people object that macro lenses are only good for closeup work;
they say that to photograph at normal distances, a standard lens is needed.
This is not true at all. Macro lenses tend to be some of the most highly
corrected lenses made and are extremely good for photographing subjects at
any distance."
I have a 100mm Sigma macro lens for when I know I'm going to do macro
photography. I also have a N..... 5T closeup lens {the only dual-element
closeup lens available) which is light, and I carry when I'm using the
SMCP-FA 80-320mm f/4.5-5.6 lens - very convenient. (Haven't tried it out
yet - I'm still waiting for delivery of a 58-62mm step-up ring bought on
ebay).
Maris
Shel Belinkoff wrote:
> I'd think that there'd be a precise definition even though some
> people may be imprecise.
>
> Shel
> "Am I paranoid or perceptive?"
>
>
>> [Original Message]
>> From: Paul Stenquist
>
>> Terminology. Some might say magnification of 1:1 or more is a
>> "macro," but I've seen 1:2 shots labeled macro as well. Of course
>> the term "close-up" has even been used to describe a portrait
>> configuration. It's all quite imprecise.
>
>
> Shel Belinkoff wrote:
>>
>>> .. between a macro photo and a close-up photo? Is there some point,
>>> some
>>> magnification, at which a close-up becomes a macro shot?
