15th Blog Post, First Published on December 4, 2016, as a Newspaper Column.
(More Photos and possibly an extended text will be added soon).
Hi, and welcome to my “HighLight & Shadow” photo Blog.
There are loads of moving objects to photograph at this time of year (this post was first published in early December), from winter athletes, to running children and dogs playing in the snow.
Predicting the effects we’ll capture in our photos of moving objects, however, can be quite confusing, leading us to blindly pick our camera settings and then accept the results. It’s quite helpful, however, to understand some of physics (yes, physics, as in high school physics) of photographing motion so we shoot motion with confidence that the images in our camera’s memory cards match the images in our minds. Today, in part one of a two part blog post on the Effects of Motion in Our Photographs , we’ll explore some of the physics of photographing motion that will help us increase our enjoyment of this fun, creative and exciting photo genre’.
The physics we’ll explore include some basic camera settings and movement itself. Let’s start by quickly talking about exposure time.
Considering Exposure Time:
Exposure time is the amount of time that light exposes a light sensitive material, which, for our purposes, is a digital camera’s sensor. Exposure time is usually referred to as shutter speed because the exposure time is controlled by the camera’s shutter. Most advanced digital cameras have shutter speeds as short as 1/4000 of a second and as long as 10 to 30 seconds.
Which Movements to Consider:
The other element of physics we need to explore is movement, and we’ll look at two different kinds of movement. The most obvious is movement of any object, living or inanimate, moving through the scene we’re photographing during the exposure. Some of these moving objects are obvious, but others, like the wings of a stationary dragonfly, ripples on a pond, clouds in the sky and outdoor shadows, aren’t so obvious.
The other form of movement we need to be aware of is camera movement, which can be intentional or accidental and can enhance or ruin our photos.
Although there is at least one more kind of movement that can affect our photos, but they are extremely rare, so we’ll only talk about these two forms of movement today. Next we’ll look at how cameras record movement as blurred or as sharp objects.
Relation of Exposure Time with Movement:
Digital photos are created when the camera’s shutter opens to expose the camera’s sensor, allowing light from a scene that is shining through the camera lens, to create a photo by activating the pixels (exposing the pixels) that make up the camera’s sensor.
The camera’s selected shutter speed determines how much time the sensor’s pixels are activated. When there is movement in the scene during the exposure, light from those moving objects moves across the sensor, exposing pixels along the light’s path for the full duration of the exposure, and that movement of light across the sensor blurs the movement’s image. A longer shutter speed creates more blur because there is more time for the light to move across the sensor, while very fast shutter speeds reduce the time for light to move across the sensor that very fast moving objects can be recorded as motionless.
A common mistake people make when shooting a moving object is to only think about the object itself and how it is moving in the scene. They forget to consider what is happening in the camera.
The effects we record when photographing movement depends more on how the camera’s shutter speed relates to movement of objects in the scene, and/or camera movement. This relationship (and other factors we’ll talk about next month) allows us to freeze fast moving objects and to blur slow moving ones. So, it’s imperative for us to understand how moving object, camera movement and shutter speed dance together on the camera’s sensor, before we can successfully control their dance and make the photographs, as we envision them in our minds.
I’m a self-taught photographer, and analyzing photos (other peoples’ and my own) was, and still is, one of the most important resources I use to continue learning this amazing art form. So lets analyze some of my pix!
Study Photo A for a minute. Why are all of the buildings, spectators and the street very sharp while the cyclists are heavily blurred? A quick observation can tell us a couple things. First, that the camera didn’t move during the exposure, keeping the main scene sharp. Second, that the cyclists were moving, and moving at about the same speed because their images are all blurred, and blurred the same amount.
Photo B is a more complex image. Pretty much everything in it is blurred, but blurred different amounts. How did I create this effect? How did I blur the background? Why is the main cyclist (A) the least blurred while the cyclist entering the photo from the left (B), the most blurred?
In photo B, objects are moving in the scene while the camera is moving too. Can you “read” how I was moving the camera?
During the exposure, I panned (moved) the camera from right to left, following A so he didn’t blur too much, yet Vedauvoo Rocks, the road and the foreground are blurred more than A is. Why?
Panning the camera with A while the shutter was open, kept A’s image in one basic position on the sensor while the images of the rocks, road and foreground were all swiftly moving across the sensor from left to right.
Now, consider what two factors blurred the B’s image much more than A’s image? The first reason is the same as above, keeping A’s image in one basic area on the sensor. But B’s image raced across the sensor because he was moving about as fast as A was, and his movement from left to right was in the opposite direction from the camera’s direction, greatly exaggerating how blurred his image is. (I purposely shot this photo in 2008 to illustrate these concepts, and am finally using it!!!).
Lastly, I want to challenge you to read photo C. Study it to see if you can determine three special photographic adjustments and/or techniques I used to create this photo. It was shot with my motor-driven Nikon F2A film camera. All the evidence is present in the photo, and it includes a third, very, very rare form of movement that we haven’t talked about yet. See if you can detect what that movement was. It’s pretty tricky to get all three, so “Good Luck!”
If you want, post your answers below in comments or by going to www. facebook.com/haywardphoto and contacting me through FaceBook messaging. You can also view my most recent Portfolios on that Facebook page.
And please, LIKE the FB page while you’re there.
Photographing motion is quite an involved subject, so in the following post, we’ll look at some additional factors to consider when photographing moving objects or using camera movement.
So, till next time, keep your eyes open, your camera handy and your imagination flowing.