Macros

Lenses that lets you come closer

Macros are designed so that the minimum focus distance is lower than a lens of comparable focal length. This allows you to take pictures of small things, insects, flowers and detailed close-ups.

Why/how use a macro

Basically the idea is to take pictures of small things and close ups. You usually will:

Use smaller apertures (when you are close, the depth of field will be very small, so you will have to use much smaller apertures (f/20 and larger).
Due to the distance and small aperture, usually need a tripod
Focus manually.

This is why, for macro photography, auto focus, vibration reduction techniques and fast lenses are really not that important. But you will see a lot of lenses with this capability because...

You can use macro lenses for other purposes

Most macro lenses are prime lenses (there are some zooms) and they can be used regularly for anything else as well. They do not have any shortcomings when you use them regularly. Auto focus, vibration reduction etc, are more useful when they are used for other purposes, not so much for macro photography. They are excellent landscape and portrait lenses.

Getting enough light

One thing to keep in mind is that the minimum focus distance is the distance between the camera sensor and the subject, and not the end of the lens. This is sometimes an issue for smaller focal length macro lenses (60mm or less), for maximum effect you need to come very close, and the camera/lens will start blocking the light. Of course there are tricks for this (flash around your lens for example), but this is why, most of the time, you would want to use 100mm or longer focal length lenses that allow you to have a bit of distance between the camera and your subject so that you can get the light in properly.

Overview

For macro lenses, the focal length does not really tell you how much larger the picture will be, as the minimum focus distance also scales. You usually talk about reproduction ratio which is how large the image will appear on your sensor.

Lens	Minimum focus distance	Weight	Notes
Nikon 35-105	cm	500g	Zoom
Nikon 105	32cm	750g	Many models
Sigma 150	38cm	1'100g
Nikon 200	50cm	1'200g

Typical setup with a Macro

Here I am trying to take a picture of a few small microchips. There is a Nikon 105 macro lens together with a TC 20E teleconverter on a Nikon D90.

And here is the result

The microchips here (Dustin) are 4mm by 2.5mm large and you can read about these chips more here.

Macro lenses on this wiki

Gallery

A microchip with a Nikon 105 using a TC 20E on an APS-C camera giving it an effective focal length of 300mm.
A typical macro setup, this time using the Nikon 200, for the picture in File:Chip nikon200.jpg
Most equipment pictures on this page is made using a Nikon 105. Here is the Nikon D700, it also has the other manual focus Nikon 105 mounted.
Cute mascot shot using Nikon 105
A tiny spider with a Sigma 150, highlighting what a macro lens can do for you.
Macro lenses can be used for normal situations as well, they are excellent for landscapes. Here is the pass road of Furka in Switzerland. This is shot from the opposite side on the Grimsel pass road several kilometers away using a Sigma 150
Comparing three macro lenses side by side. From left to right Sigma 150, Nikon 200, and Nikon 105.
Microchip photographed using the Nikon 200. This is with a APS-C camera, at (almost) the minimum focus distance.

These pages are for Amateur Photographers and not really for seasoned photographers and professionals. I have no affiliation or commercial interest with any brand/make. I write from my own experience. I ended up using mainly Nikon, so I am more familiar with this brand than others. See price for notes on pricing as well as photography related links.