Macro

A true macro lens has 1:1 magnification or better. The magnification is relative to the sensor size in the camera. 1:1 magnification means that a subject that is the same size as the sensor will fill the whole frame.

Some manufacturers will sell lenses with 1:2 magnification as macro lenses but they are not real macro lenses. The magnification is only half of a true macro lens and the optical quality is generally significantly lower. One exception is Carl Zeiss that sells high quality macro lenses with 1:2 magnification.

The distance to the subject is not a measure of the macro capabilities of a lens. Compact cameras are often specified with how close they can focus on the subject. This is an oversimplification that is useless. Different focal lengths gives the same magnification at different distances. Using a short focal length like 50 mm makes it much easier to photograph without a tripod but the short distance to the subject will make it harder to avoid shadows and tend to scare animals and insects. 150 mm gives a comfortable working distance but it is harder to avoid camera shake and the weight of the lens can be tiresome.

Common sensor sizes

• Nikon D70 - 23.7 x 15.6 mm
• Nikon D200 - 23.6 x 15.8 mm
• Canon 350D/400D - 22.2 x 14.8 mm
• Canon 20D/30D - 22.5 x 15 mm