A macro lens is a camera lens designed for photographing small subjects at very close distances. They can focus much nearer than normal lenses, allowing you to fill the frame with your subject and capture more detail.
They are typically used when photographing insects, plants, and small products, but are versatile enough to be used in all sorts of situations. Virtually every subject has interesting details which can make for fascinating close-up photos.
Although macro lenses are optimised for close-up work, most can focus all the way to infinity and make excellent general-use lenses as well. Many professionals also use them as a portrait lens due to their ability to capture lots of detail in ultra-sharp focus.
Magnification Ratio
The most important property of a macro lens is its magnification ratio, also known as the reproduction ratio. This describes how much the subject will be enlarged in the final image.
The magnification ratio of your macro lens determines how large the subject will appear in the final shot. Image by Andrew Snyder.
A magnification ratio of 1:1 means that when the camera is positioned at the closest focusing distance, the image formed on the sensor will be the same size as the subject. For this reason, a 1:1 ratio is also called "life size" or "standard".
A lens isn't considered to be "true macro" unless it can achieve at least 1:1 magnification.
Most macro lenses with a medium to long focal length (100mm to 200mm) are capable of achieving a reproduction ratio of at least 1:1. Some go as high as 5:1, allowing for extreme close-ups of subjects like insect heads.
Macro lenses with a shorter focal length (around 35mm to 50mm) are often limited to a ratio of 1:2, which means that the subject will appear half "life size". However, you can use extension tubes to achieve 1:1 magnification.
Many zoom lenses are marked as "macro", but in reality they usually don't allow for magnification greater than about 1:3. They also tend to produce lower-quality photos than a proper macro lens.
Focal Length
Macro camera lenses normally have a fixed focal length (i.e. they are "prime" lenses). There are a few zoom macro lenses available but they tend to be of low quality and won't achieve such high magnification ratios as prime macro lenses.
Macro lenses are available in a range of focal lengths for different purposes.
The most common focal lengths are around 50mm, 100mm, and 180mm, although the exact values depend on the manufacturer.
Macro lenses with short focal lengths (50mm to 60mm) are cheaper, smaller, and lighter. However, you have to get much closer to the subject, which can be a problem when photographing things like butterflies, as they are easily scared away. You might also find that your shadow gets in the way of the shot.
Long focal lengths (150mm to 200mm) are more expensive, larger, and heavier, but they give you more "working distance" between you and the subject. They also give a narrower depth of field, allowing you to throw the background further out of focus, which can help to isolate the subject.
Macro lenses with intermediate focal lengths (90mm to 100mm) provide a good compromise between these factors. They tend to work well in a wide range of conditions, making them a popular all-round choice.
Focal Length Choice
Choosing a focal length depends on your needs, your budget, and the subjects you intend to shoot, as summarised in the following table. If in doubt, choose a lens with an intermediate focal length.
| ~50mm | ~100mm | ~180mm | |
|---|---|---|---|
| Price | Cheapest | Mid-range | Most expensive |
| Weight | Lightest | Medium | Heaviest |
| Size | Smallest | Medium | Largest |
| Working Distance | Closest | Medium | Furthest |
| Subjects | Products, small objects | Insects, plants, small objects | Insects, small animals |
Image Quality and Sharpness
Most normal camera lenses focus by moving an entire assembly of optical elements. While this is fine for medium- to long-distance focusing, it can result in a noticeable reduction in optical quality at very close distances.
To counteract this, macro lenses use a "floating" optical element which constantly adjusts the lens's internal geometry to give pin-sharp focusing, better contrast, and consistently high picture quality at all focus distances.
Some lenses also include a vibration reduction (VR) system. This can be particularly useful when shooting at slow shutter speeds or without a tripod, as even tiny movements can produce noticeable blurring in the final photograph.
Macro lenses normally have much wider apertures than normal lenses, giving excellent low-light performance. The flip-side to this is that depth of field is very narrow, particularly for lenses with a long focal length. A tripod is essential for holding the camera steady, and a macro focusing rail will help you easily fine-tune its position.
Focusing Mechanism
Most modern macro lenses use an autofocus system. This makes it much easier to get a sharp image, especially with longer lenses which have a narrower depth of field. There are two types of autofocus mechanism - the traditional, screw-driven type, and the more advanced "silent" type. Silent autofocus systems are more expensive but are less likely to scare a nervous subject.
Older macro lenses, and some specialist lenses such as Canon's 1-5X, use manual focusing. These can be more difficult to work with, and make it even more important to use a tripod to keep the camera absolutely still.
Some lenses use "internal focusing" which adjusts the focus by moving just the inner group of elements. The outside of the lens does not move at all, reducing the chances of accidentally touching the subject or scaring it with the lens's movement.
Alternatives
There are a number of alternatives to using a macro camera lens. The picture quality generally isn't as good, but they can work out significantly cheaper.
Left-to-right: Extension tubes, bellows, close-up lenses, and reversing rings can all be used instead of macro lenses, although the quality varies.
Extension Tubes
Extension tubes fit between the camera lens and body. They contain no optical elements and their sole purpose is to move the lens further away from the sensor or film, giving a closer focusing distance and greater magnification ratio. Extension tubes can be stacked to increase the effect.
Bellows and Focusing Rails
Essentially like infinitely-adjustable extension tubes, bellows and focusing rails allow large improvements in magnification but also greatly reduce the amount of light reaching the sensor. For this reason they are usually only used in studios.
Close-Up Lenses
A close-up lens mounts onto the front of your lens using the filter thread. They act like a magnifying glass, simply enlarging the image before it hits the sensor. They tend to be of poor quality but offer a cheap, quick-fix alternative to macro lenses.
Reversing Rings
A camera lens works by shrinking an image onto your camera's sensor or film. By mounting the lens backwards it enlarges the image instead. Reversing rings are cheap and easy to use, but you lose the lens's automatic functionality, and the focusing point becomes fixed so that you have to physically move the camera to make the subject sharp.
Buying a Macro Lens
Because they are such specialist pieces of equipment, the majority of macro lenses on the market tend to be very high quality.
Canon and Nikon (Nikkor) are considered to be the best macro lens manufacturers, so if you use either of these brands of camera and can afford them, they are the way to go. For the more budget-conscious, Tokina, Sigma, and Tamron also produce some excellent lenses.
As with anything, once you've narrowed your selection down to a few models, be sure to check online reviews, and shop around for the best price. Two good places to start are Amazon and Adorama.
Cover image by The Preiser Project.
