Originally posted by Aaron1971 So, what exactly does the tube do for you? Also, if you could recommend a beginner's level macro lens what would it be?
Also, just for conversation's sake, what is the difference between macro photography and close up photography?
I apologize again, I am very new to photography.
When you focus your lens on a closer subject, the lens is moved further from the body of the camera, and therefor the film/sensor. After a while, the focusing threads on the lens run out. To focus closer yet, one way is to put an extension tube between the lens and the camera, moving it further forward.
So, when I take my M 100/4 macro lens, the helicoid is fully extended when the lens is 50mm from the body of the camera, giving me 1/2 life size at the film/sensor. By adding the 50mm extension tube (no glass, just the mount and aperture levers) I can move the lens 100mm from the film plane, and get 1:1 or life size on the sensor/film. If I set the lens to infinity focus, I still have 50mm of extension with the tube, giving me 1/2 life size again.
If I put the 50mm tube between the camera and a 50mm lens, the lens will give 1:1 on film/sensor when the focus ring is set to infinity. It will focus even closer with the focus ring, and give even more magnification.
In the case of the 400, The 50mm tube gives me about 1/8 on the sensor/film when focused at infinity. Because of the optical characteristics, this doesn't give precisely that, but the advantage for me, using my 30 year old lens, is that I can focus the lens closer than the 5 meter or 16.5 foot close focus limit. For me that means that I can take a picture of something at closest focus that is about 5x7.5 inches on film, and smaller than that on sensor. Little birds work out doing this. A sparrow is between 4 and 6 inches long, so it just about fills the frame with the extension tube on the back.