Choosing a Macro Lens

Getting up close is a great way to capture small subjects or snap abstract images. However, you can’t get up close with just any lens. Without a macro lens, DSLRs and mirrorless cameras can’t focus on objects close to the camera lens, so they can’t capture a true macro image. To capture objects up close, you’ll need a macro lens.

But, choosing a macro lens can be rather confusing. What do those ratios like 1:1 mean? How do you tell how close you can get with that lens? Is it better to get a wide angle, or a telephoto? Here’s what you need to know to choose the best macro lens to get you in close.

Macro lens ratios

To understand what a macro lens ratio is, you first need to understand the basic concept of a digital camera. When light enters the camera through the lens, the scene that you see hits the sensor and is recorded as a digital image.

Of course, most of the time, what we see is much larger than the sensor inside of a camera. If you are photographing a tree that’s ten feet tall, of course it’s not going to be ten feet on your camera sensor. The lens ratio gives us an idea of just how much space an object takes up on the camera sensor, versus how much space it takes up in real life. If you are photographing an item that is six inches tall, and it takes up one inch on the sensor, it’s being captured by the camera in a 1:6 ratio.

For macro photography, ratios help indicate how big you can make those tiny objects appear. A true macro lens is usually considered as a 1:1, so a bug that’s 5 cm tall will be 5 cm tall on the sensor. Some lenses are marketed as macro but have a 1:2 ratio, so that 5 cm bug is just 2.5 cm on the sensor.

Why does the ratio matter? A lens with a 1:1 ratio allows you to get in close and capture the object at life size. Magnification is of course affected by distance. You can use most macro lenses to take a picture of a tree from a distance because you don’t achieve that 1:1 ratio until you are close up. A macro lens will achieve that ratio at the minimum focus distance.

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Minimum focus distance

a close-upIf you’ve tried to take a close-up with a non-macro lens, you probably heard the lens whirring away, trying to find a focal point and failing. Because of the design of a lens, the lens can only focus on objects so close. A macro lens can focus on objects that are closer to the front of the lens than a normal lens.

The minimum focus distance will be listed in a lens’ tech specs, and it simply indicates how close you can get to the subject and still focus. To achieve the maximum ratio, like that 1:1, you’ll need to be as close to the subject as the lens allows, or right at that minimum focus distance.

When it comes to the minimum focus distance, the focal length of the lens matters too. A 35mm lens needs a very small minimum focus distance of just a few inches in order to achieve a macro ratio of 1:1. A 200mm lens, however, can achieve that ratio from a few feet away, thanks to the zooming power of the lens.

Focal length: Should you get a wide angle or telephoto macro lens?

telephoto macro lensMacro lenses are available in several different focal lengths. You can pick up a macro lens that’s a wide angle like 35mm, a standard like 50mm or a telephoto like