Part 2

Introduction

Are you ever frustrated by your inability to freeze subjects in some of your pictures—“People. Stop moving!  I’m trying to get your picture?”

In this article, we are going to explore what causes motion blur (and why it could actually be a good thing). Believe it or not, if used correctly, it can actually be useful.

Learning why it happens can alert you when it is likely to happen to help you avoid it—but also to know when it might be to your creative advantage.

Slow Shutter Speeds

The underlying cause for motion blur is using shutter speeds slower than necessary to freeze motion. It may be you aren’t holding the camera steady or your subject(s) are moving too much; either way, you will have to raise your shutter speed.

But how much?

There are multiple variables to consider, such as the direction of movement, subject distance, and focal length.

Subject Movement

Direction of Movement                                           

You will find it easier to freeze motion if your subject is moving towards/away from you (vertical axis) than if it is traveling from side-to-side (horizontal axis). 

Even though your subject is moving the same speed, changing your perspective will yield better results.  This is because of perceived motion.

In the same way that your eye perceives greater motion when a bird flies across your vision, your camera sensor will also perceive greater motion for a subject moving across it.  Conversely, the number of pixels crossed on the sensor will be reduced when the motion is moving towards/away from it.

Perspective: How Close is Your Subject?

Have you ever tried tracking objects from the side window of a moving vehicle?—First, at the side of the road, then, at the trees in the distance. Which subject was easier to follow? The farther one, of course. Even though the road and trees were moving at the same speed relative to you, it was easier to focus on the distant object.  Once again, it is the perspective that is key here. Even though a subject is moving at a fixed speed, being physically closer means larger subjects and exaggerated movements. This requires a faster (much faster, in some instances) shutter speed than the same subject from a distance.

So How Much Do I Increase My Shutter Speed?

If I calculated shutter speed tables for each motion variable, could you remember both charts?  Furthermore, many scenes contain multiple motion variables—meaning, more charts and increasingly complex calculations.  Now try to imagine memorizing . . . I think you get the point.  It would be a waste of time—yours and mine.

Instead, I’m going to show you a better way . . . experiment.  And in time, with practice, you will begin developing a taste for which shutter speeds to use in a given scenario.

But where do I begin? you ask. This leaves me no better off than where I started!

You’re right.  I’m not going to leave you with only some “helpful” lecturing.

Below is a table of generalized shutter speeds.

These will give you a good starting point, from which you can deviate as necessary.

Camera Movement

Lens Focal Length

Have you ever observed how much harder it is to keep a subject in the viewfinder when using a telephoto lens—especially moving objects? Every little movement—including the shake of your fatiguing hands—is exacerbated. This is the same thing that happens when using binoculars. You are still changing perspective, albeit without physically moving. Instead, the change is in the level of zoom. For each successive zoom lens increase, you’ll need an increase in shutter speed.

There is actually a formula for estimating minimum handheld shutter speeds and their corresponding focal lengths:

This means that if you had a lens with a focal length of 50mm you’d need to use a minimum shutter speed of 1/50. This is only a starting point, for freezing moderate movement.  So don’t latch on too tightly. 

Creative Zone

Every picture you take should tell a compelling story. And what better tool to help than motion blur.

Next time your scene has movement, instead of trying really hard to avoid it—and being frustrated when you can’t, think what if I included motion blur in my photo? Would revealing the subject’s motion enhance my photo’s story, or present a unique perspective?

The creative range for motion blur is 1/30^th of a second to 30 seconds.

Here are some examples:

Because our eye is drawn to the sharpest areas, make sure that each of your photos has a focal point to draw in your viewer’s eye.

Conclusion:

As with any subject you are learning, there are two aspects: technique and art.  You need to know the numbers to become proficient.  But don’t let the familiarity of concise bonds keep you from driving off the road and exploring the unknown—the creative side.  Subjective, and inexact?  Yes, but absolutely essential for mastering the art of photography, or any art form, for that matter. The good news is that the more you practice, the more experience you will develop; and the more experience you develop, the more confident you will become.

So, no, motion blur from too-slow shutter speeds isn’t necessarily bad.  It depends on your perspective and the results you are trying to achieve.  And hopefully, I’ve enlightened you to the possibility of claiming motion as a friend—once in a while.

Real world example:

Revisiting the race car scenario from part 1, let’s change the time of day to evening.  The sun is still visible, but it’s nearing the horizon. This means the amount of light available is starting to limit your camera’s ability to freeze fast action.

Troubleshooting:

Low Light

Trying to mitigate motion blur in low light using one of your camera’s auto exposure compensation modes can be counter-productive.

• Using aperture priority or program—your camera will automatically fix the low light problem by slowing down the shutter speed. However, this exacerbates the blur.
• Using shutter priority—enables you to select the correct shutter speed. However, this will leave you with an underexposed photo. Your ISO and aperture will be maxed out, leaving you with no further stops of light.

If motion blur is only from camera shake, a tripod will solve this. If you forgot to bring one, try resting your hands on a rock or against a tree.

But, if it’s subject movement, time to swap lens for a wider aperture lens (if you have one).