Macro usually is defined as 1:5 up to 5:1, or somewhere in that range. Subject size versus it's magnified size on film.
Some lenses can magnify the subject on the film up to life size. These are macro lenses. Macro lenses come in various focal lengths, such as 60mm, 100mm, 150mm, 200mm, etc. The longer the focal length the further the distance from subject at a given magnification. So a 200mm lens's front element is much further away from an angry red-ant hill than a 50mm lens when both would be magnifying the subjects at 1:1! This is called 'working distance'.
There are various ways to get that subject magnification without using a macro lens, such as mentioned above. Canon makes a screw on achromatic filter like lens (2 elements, 1 asymmetric, multicoated -- all good) called the 500D for use with longer lenses, not necessarily macro lenses. It allows you to get pretty good magnification based on lens focal length and the ability of your lens to focus at a given subject distance. On my 70-200mm Nikkor it does a great job, but that takes a 77mm filter and the 500D cost a bundle. I can use it on lenses with smaller filter sizes by using step down rings to adapt the filter size. Pure macro lenses and extension tubes do not put anything into the light path that's not part of the original lens, so they do not degrade it at all. Any other option does degrade it to some degree; the 500D has very little deleterious effect, but it is noticeable as a very slight softening.
These were both on a Nikon D200, I don't have and macro shots on film (from this century):
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Friday, May 29, 2009
What is Macro?
Tuesday, May 26, 2009
What's Yours Is Mine, And It's For Sale!
If you look at a picture in your web browser, you have ALREADY DOWNLOADED IT. There is no implied intent for you to keep it, especially to reuse it for your own purpose, to sell it or otherwise distribute it.
A house's door left unlocked is no invitation to remove furniture, is it? Neither is listening to a song an invitation to make a copy and sell it, nor to provide copies from your copies (to lots of people on the internet.) If you copy it from the radio, or media you buy, or just d/l it from somewhere and don't spread it around, then you have got the right spirit.
It needs to be clear that just getting your hands on something does not give you any right to sell or distribute it: that's clearly 'conversion' (i.e. theft by conversion). It is pretty clear to most people that they can not go into a store and pick something up, and then claim it as their own without paying for it.
Intellectual property may be physically easier to acquire, but it's no less someone else's property. The internet has created a 'virtual nation' of deniers, who say, in effect, "It's just me, one person doing this thing, so it's not so bad." There are 10's even 100's of millions of those "just me's" around, so it is actually "so bad".
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