Shopping for a new lens: Lens Minimum Focusing Distance

Hey guys. This is the third post in Shopping for a new lens article series. Last time we talked about Lens Aperture, which you can check out right here if you haven’t already done so. Today we will be talking about Lens Minimum Focusing Distance, which is yet another important aspect to consider when getting a new lens.

What is minimum focusing distance?

A lens’ minimum focusing distance is the closest distance your lens would allow you to get to your subject while still maintaining sharp focus.

In general, the closer you move to your photographed subject, the larger you’d be able to render it, and the more it’ll fill the frame. This is particularly important in digital photography since any attempt of cropping and enlarging would jeopardize image resolution and quality.

That said, you ought to note that you can only move in so close before your lens loses its ability to maintain focus on your subject.

Rule of thumb is, the further away your lens is from the digital sensor or film, the closer it’ll be able to focus, and the more magnification you’ll be able to achieve. That is why lenses tend to get longer when you turn the focusing ring.

It’s also known that, the wider the lens (the shorter the focal length) is, the closer it will allow you to focus. The longer the focal length is (i.e. telephoto lenses), the longer would be the minimum focusing distance a lens can support.

Definition of how close is close-up usually depends on the manufacturer and varies from model to model. However, a minimum focus distance that is anywhere from 12 inches down to less than an inch can be considered close-up.

To shoot macro photography you oughtta have a macro lens, a lens specifically designed for ultra close-up photography by using a long barrel which job is to move the lens further away from the digital sensor or film, thus offering you shorter focusing distance.

However, you can still venture into close-up photography by getting what is called Extension Tubes.

What are extension tubes?!

An extension tube, as the name suggests, is a tube that can be mounted on a camera that supports interchangeable lenses.

The tube itself contains no optical elements. Its sole purpose is to move the lens further from the image plane, thus getting you closer to your subject.

Extension tubes of various lengths can be stacked, decreasing lens-to-subject distance and increasing lens-to-image plane distance, thus increasing magnification.

Extension tubes are a great solution and can be bought for as low as $5 if not less. Of course higher-end products come in more expensive prices but isn’t that how it usually is!

How can I tell a lens’ minimum focusing distance?

You can tell your lens’ minimum focusing distance either by checking your camera manual guide, or alternatively by looking at the side of your lens.

You should find a number representing distance next to a small flower graphic. This number can be in feet, inches, or fractions of a meter as shown below.

The first image shows a 50mm canon EF lens. As you see, this lens offers a 0.45m which is 1.5 feet minimum focusing distance. This means that you can get as close as 1.5 feet to your subject with this lens before you lose the ability to focus moving any closer.

The second image shows a 18-55mm canon EFS lens. As you see, this lens offers a 0.25m which is .8 feet minimum focusing distance. This means that you can get as close as .8 feet to your subject with this lens before you lose the ability to focus moving any closer.

You can also notice the increase in minimum focusing distance as the lens gets shorter in focal length, as stated above.

Close-up & personal is good, and good things are seldom for free

An important thing you need to note is, the further away the lens from the image plane is, the closer the focus, the greater the magnification, and the darker the subject gets under the same aperture opening.

The closer the lens is to the subject, the greater the loss of light. This would force you to change your camera exposure settings to compensate for the light loss either by increasing the exposure time or pumping up your ISO level.

This concludes our talk about lens minimum focusing distance. Next in the series is Image Stabilization. stay tuned…

You might also like to check out the previous 2 articles in this series:

Shopping for a new lens: Lens Aperture	Shopping for a new lens: Image Quality