A macro lens is a lens that specifically allow you to focus extremely close to a subject so that it appears large in the viewfinder. "True" macro lenses are able to project subjects onto the camera's sensor life-sized at a 1:1 reproduction ratio resulting in a 1.0x MM (Maximum Magnification) at the lens' MFD (Minimum Focus Distance, measured from the subject to the sensor), meaning that a 0.6" (15mm) long subject would be projected 0.6" (15mm) long onto the sensor. While that doesn't sound like a big deal, keep in mind that a subject measuring only 1.4 x .9" (36.0 x 24.0mm) will completely fill the frame of a full frame DSLR. When viewed on a large display, tiny details in your subjects become conspicuous features while using true macro lenses.
A select few macro lenses actually exceed life-sized reproduction for the ultimate in close-up DSLR photography.
Let me share a sample image. (sorry for big one)
Some subjects are so tiny they need extreme magnifications. This close-up
portrait of a robber fly required a whopping 4:1 magnification ratio, meaning
that the image projected on my camera's sensor was 4x larger than the fly itself.
I hope I satisfied your answer and also below are some macro photography tips that might help you.
- Learn to focus manually
- Learn to be patient
- Use a ring flash or twin light flash when shooting macro
- Crop images tight for online viewing
- Set shots up (This shot of a water droplet was taken with a plastic bag (and a pin hole in it) being held over a fish tank
- Aperture Settings
Thanks