yamatama wrote in post #17474735
I have read about extension tube but totally forgot about them. How would they work with a lens like The 135? Is there a quality decrease? whats the diference from a true macro? I was considereng those 2 because I love IS on lenses but ia it that valuable on macro lenses?
Extension tubes work great on most lenses. Note, however, that they are more effective on shorter focal length lenses. You can use more than one, or a longer one, to get more magnification.
By magnification, I mean the ratio of image size (on the sensor) to the actual size. So, if you are shooting a flower that is 72mm wide and fill the 35mm format frame with it, the magnification is 36mm/72mm = 0.5, or 1:2.
The best way to find what magnifications are possible with different lenses and extension tubes is to look the information up in the lens manuals.
Extension tubes are empty tubes (no glass inside), so some say they have no effect on image quality. But they cause the lens to focus at a distance it was not designed for, and in that sense there could be some deterioration of IQ. Usually it is not noticeable. Anyway, most of the time when shooting macro or closeup, you stop down to f/11 or f/16 to gain DOF, and that also causes some IQ deterioration, also with macro lenses. Most of the time all lenses look the same at f/16.
A true macro lens is more convenient than a regular lens with extension tubes because you can focus close without removing the lens and fitting the tubes. A true macro can also be sharper because they are prime lenses, and are designed for close work - but see the comment about shooting at f/16.
IS is very useful until you get close to your subject (roughly around 1:2). Then the usefulness is gradually reduced but may still help.