Peter West Carey Photography

Tag: camera

Depth Of Field: Changing Focus Points – Photography Experiments

Changing Focus Points

Let’s try a little Jedi training with you today. I’m not going to give you any supporting images to help you see what might happen.

“LUKE: (laughing) With the blast shield down, I can’t even see. How am I supposed to fight?

BEN: Your eyes can deceive you. Don’t trust them.”

Actually, Old Ben had it wrong, I want you to trust your eyes.

Oh, this is post 4 in the 40 Photography Experiments.

Now then, yesterday you learned to change the depth of field in a shot using the Aperture. Today let’s see what happens when you change the focus point in a scene.

Here’s the experiment you can run:

1) Scene setup: You will need a long, flat surface, like a wall or a floor. A table or counter will work as well.

2) Place a yard stick along the table or wall. Yeah, I know, the chances of actually owning a yardstick are slim. So set up an object every foot along the table for a total of six feet. Taper them side to side slightly so you can see them all at once, much like you did yesterday.

3) Switch your camera to Aperture Priority. Choose ISO 800 and pick the smallest numbered aperture you can (e.g. f/4, f/1.8).

4) Switch your camera to select only the middle focus point. There are dozens of ways to accomplish this depending on your camera so I suggest you consult your manual to learn how to pick just one focus point and keep control of it. If you really can’t find it after reading for 15 minutes, leave a comment and I’ll help you.

5) Zoom in to 50mm or as close as you can get to that focal length. If you are using a point and shoot, zoom in half way from the nearest to the farthest zooms.

6) Focus on the first object and get as close as you can before your camera won’t focus any more. This will be somewhere around 1-2’/.3-.6m.

7) Make sure you can see all the objects on the table/floor/counter. You can use a wall that has some type of pattern on it. If you have no patterns, give your kids some crayons and tell them to go to town on the wall. Instant, random patterns.

Get ready, get set…

Let’s just review where you’re at as we’re doing this without photo aids.

Stuff spaced out at one foot/.3m increments on a table/counter/floor or some type of pattern on a wall. You have control of your Aperture and ISO and you will let your camera take control of Shutter Speed.

You selected the smallest numbered aperture you can, likely f/3.5 or f/4, but maybe less. It’s not too important right now. Oh yeah, make sure there is decent lighting. And chocolate. It’ll help, trust me.

8) Take a photo while focused on that first object.

9) Focus on the second object. Do not move your camera front to back or too far left and right. Panning to the side (as if your camera is on a swivel) is best. Baby steps.

10) Take a photo.

11) Focus on object #3 as above and take a photo.

12) Continue this until you have shot all objects in turn.

Done! With the shooting.

Now review the images on your computer. Run through them one by one and look to see how many objects are in focus in each picture.

Remember, you changed nothing in between the photos as far as your camera goes except the point of focus (shutter speed changes in this experiment are irrelevant). So how many objects were in focus when you focused on the first object and how many were in focus on #4?

What happens if you run the experiment again and choose f/8 or f/22?

I’m not going to give the answer to this one today, maybe on Monday. I’m waiting for you to have your “LUKE: You know, I did feel something. I could almost see the remote,” moment.

What? Too many Star Wars references?

Monday we will build on the Depth Of Field concept by changing distance and zoom.

Questions? Pop ’em like Pez in the comments section below. or email me at peter@peterwestcarey.com.

Photography Basics – A 43 Day Adventure, and its companion 40 Photography Experiments, are series written by professional photographer Peter West Carey. The series are designed to unravel the mysteries of photography, helping you can take better pictures. Subscribe here to receive all the updates and bonus material. Your comments are always welcome.

If you enjoy the series, consider learning photography first-hand on a professionally led international photo tour in Nepal or Bhutan. More information can be found at Far Horizon Photo Tours.

October 26, 2018
Metering Modes: How Your Camera Sees Light – Photography Basics
Let’s jump right into the guts of your camera and how it makes exposure decisions.

Metering Modes

What are Metering Modes? Your eye and brain are fantastic at figuring out what is the correct exposure for any scene and adjusting to it. You squint without thinking and in dark situations your pupils dilate to bring in more light (they do that at the eye doctor as well but that’s just because of those wicked drops).

Your camera has to try to do the same thing: judge the amount of light in a situation and set the ISO, Shutter Speed and Aperture appropriately to make a proper exposure.

NOTE: Metering Modes come into play when you are shooting in any Camera Mode other than manual.

The problem is, a camera is not nearly half as cool or as complex as your brain and eyes. So the camera manufacturers have come up with some methods for metering light and trying to figure out the best settings.

Different Modes for Different Situations

For most DSLRs and mirrorless cameras there are three different metering modes in common: Matrix or Evaluative, Center Weighted and Spot. In all of these modes (and others, depending on manufacturer) the camera uses a special sensor to evaluate light hitting it, as if it were hitting the main sensor.

As mentioned before, light is measured in a camera in stops. From one stop to the next is either half as much light or twice as much light. The dynamic range of most cameras, that is, the range of stops captured in a single image, is maybe 8 stops. Cameras improve all the time and now top 13 stops.

The dynamic range of the human eye in a single instance is estimated at 14 stops, with an overall dynamic range of around 25 stops.

As the camera is limited in range (we’ll ignore HDR for now), it has to pick what gets favored for exposure. Maybe a scene has a dynamic range of about 15 stops and your camera is limited to 7 stops. What to do? Metering will pick what’s important and select an exposure based on that. Let’s look at the modes.

The Three Main Metering Modes

Matrix/Evaluative Mode is going to attempt to meter 80% of the scene, give or take a bit. This mode works well for a wide range of subjects especially if there is a lot going on and you aren’t sure where you want to meter. It has its limits as it doesn’t cover the corners (usually not a big deal) and may try to balance a scene with a wide range in a manner not to your liking. This mode is the king of compromise.

Center Weighted (sometimes shown without the spot in the very center) starts to narrow things down a bit. In a lot of cameras the light reading is taken from the center 13% of the frame. A number of cameras even have the ability to change this percent to three different values. Anything not in the general center area will be ignored as far a light metering is concerned.

Spot Metering is handy when you know exactly what you want exposed properly and it is relatively small. Spot metering is a circle of about 2-3% of the frame (cameras will often show an actual center spot in the viewfinder to aid in selecting the area to meter). This can be handy when scenes are back-lit or there is a lot of brightness, contrast and other action going on, but maybe only one element is important to the exposur

Metering Modes in Real Life

Now lets take a look at how these metering modes can affect your image. I have set up a likely scene on a chair using my daughter’s friends Lamoin and Hopster.

In all these scenes I set the ISO to 100 and the aperture to f/8 to hold them constant. Only the shutter speed will change and it will only change because the camera is sensing differences in the light.

It will sense differences in the light because it will use different modes and we’ll start at the top with Matrix or Evaluative.

ISO 100, f/8, 2 Seconds

The shutter was open for two seconds. The camera metered for the entire scene and faced with a tough choice (lots of lights and darks) it picked something it thought was middle ground. If it could think. It can’t. Ha ha ha ha. Only Hopster can think. Ok, enough nervous laughter, next is Center Weighted.

ISO 100, f/8, .6 seconds

That superimposed oval is about the area the sensor metered (and a good mathematician will tell me it’s far greater than 13%!). You will notice Hopster is much better exposed with only .6 seconds of a shutter speed, but we’re losing Lamoin’s hooves and the chair is getting dark. Still, I like this better than the first. Spot Metering time.

ISO 100, f/8, .3 Seconds

As the spot is only on Hopster’s white ‘fur’, the camera is attempting to exposure properly for it. The camera did a decent job, but you can notice what happened to the rest of the scene. Dark, dark, dark. What happens, though, if we move the spot to the darkest part of the scene, to the area just below Lamoin?

ISO 100, f/8, 10 Seconds

Zoiks! While that one patch of bison fur is exposed well, the 10 second shutter speed makes everything else overexposed. Can we mitigate this a bit?

ISO 100, f/8, 3.2 Seconds

That’s a bit better as far as Lamoin is concerned. Hopster is still blown out and not the least bit happy.

It is important to note DLSRs are often equipped to favor metering at times. Such as in Matrix Mode. Often the focus points that are locked on a subject will get a slight bump in their overall importance for light metering as the camera knows this is likely the main subject. Others take it a step forward and use face detection software to know where a face is and expose for that, instead of an overall evaluation of the scene.

What About My Phone?

Your phone uses Matrix or Evaluative metering most of the time. It looks at the whole scene and tries to balance the exposure.

Using an iPhone as an example (although most phones work the same), a large rectangle appears to show where the metering and focus are locked, when locked. In this example, the box is closer to center-weighted than true evaluative.

But that makes the leafs a little over exposed. All you have to do to change the area where your phone meters and focus is to tap that spot on the screen. In this case, I want the leafs better exposed, thus I tap them.

That’s better. What happens if I tap the ground to make it better exposed?

Whoa now! The ground is brighter but now the leafs are totally blown out and my Shutter Speed is so slow that things got blurry.

You might also notice how your phone will put a focus and exposure box around someone’s face when it finds one in the scene? That’s because the camera assumes you want the face exposed correctly and 99 times out of 100 that is true.

The point here is you can pick your exposure area in a phone just like you can in a DSLR or mirrorless camera. This “tap on the screen” method is also true for most drones.

The Right Mode for the Right Scene

So which mode is right for which situations? Without being by your side for every shoot you go on, I can make some generalizations:

Matrix/Evaluative Mode
- Good general walk around setting
- The beach
- Midday sun
- Cityscapes
- Lightning
- Bison
- Mountain ranges
- Grand vistas
Center Weighted
- Concert/Band
- Sunsets/Sunrise (to meter and then recompose)
- Group shots
- Waterfalls
- Portraits
- Birds
Spot
- The Moon
- Sports action from afar (where the subject is pretty much filling the center of the lens)
- Back-lit subjects
- Yeti
Wrapping Up Metering Modes

Play around with the modes and get to know them better. You will find times when the main subject is still too bright no mater how much you adjust the exposure compensation (more on that next week).

That is likely because your camera is in Matrix Mode and trying to balance everything. Switch to Center Weighted and chances are you will find things starting to come around. Get more precise with Spot and the control becomes even more finite.

To access the different metering modes, look for a dial or knob with the icons above on it. On some Canons it is a button press then a wheel turn. On Nikons it can be a rotatory dial on the side of the eyepiece.

Next Up: Camera Modes(and how to stop using the green rectangle!!)

Questions? Pop ’em like Pez in the comments section below. or email me at peter@peterwestcarey.com.

Photography Basics – A 43 Day Adventure, and its companion 40 Photography Experiments, are series written by professional photographer Peter West Carey. The series are designed to unravel the mysteries of photography, helping you can take better pictures. Subscribe here to receive all the updates and bonus material. Your comments are always welcome.

If you enjoy the series, consider learning photography first-hand on a professionally led international photo tour in Nepal or Bhutan. More information can be found at Far Horizon Photo Tours.
October 11, 2018
And Then, ISO – Photography Basics

Shutter Speed and Aperture. Check!

ISO, The Sensitive Side of Exposure

When it comes to the last side of the Exposure Triangle; you need to be nice, because it’s sensitive. ISO is sensitive. REAL sensitive.

As a matter of fact, it is the only thing in your camera that handles the sensor’s sensitivity to light.

It works like this: Low ISO (50 or 100) is less sensitive to light and thus, needs more of it to make an exposure. As you move up the scale to 200, 400, 800, the sensor on your camera becomes more sensitive to light and needs less of it.

You might think this is awesome. Just jack up the ISO to 128,000 and shoot in the dark! Wahoo!

Your Camera’s Sensor, Up Close

Look, you’re camera is not a bunny and does not eat carrots (needed to get a bunny reference in). There is a consequence for being more sensitive to light; your sensor is more sensitive to noise as well. Let’s take a look at how a typical camera sensor collects light. I’ll try to make this easy.

Pretty, isn’t it? That’s the sensor in your camera, be it DSLR, smartphone, etc…. It is made up of all these dots. MILLIONS of them (that’s the Mega in Megapixel). This image is looking straight at the sensor and there are various patterns to these dots, it’s ever evolving. Let’s turn it on its side.

This is looking at the side a row. Over each actual light sensor is a color filter to only let in red, green or blue. Above that is a microlens to focus the light. Look at your keyboard and pick four keys in a box shape, 2×2. Now imagine 10-30+ million of these sensors in that space. Amazing, simply amazing.

How Does ISO Work on a Sensor?

Storm clouds churned up by Hurricane Irene unleash their power over Zihuatanejo Bay in Mexico.

Each sensor is energized with electricity to accept light and record when it is struck (when the shutter opens to let light hit it on a DSLR, or all the time on other devices). All of those sensors are energized. And that’s where the limits come in.

When set to a low sensitivity (ISO 100), there isn’t much current passing through the sensor area. This lack of sensitivity is overcome by letting in more light, either by a longer Shutter Speed or a fully open Aperture.

But when you adjust the ISO to around 400 or 800 something else starts to happen. That sensor area needs to become more energized to detect the lower level of light. As it becomes more and more energized, with electricity, every sensor gets so energized that little bits of electrical current get lose and starts to bug their neighbor.

Not only are the sensors sensitive to light, they are are sensitive to electrical current (as that is how they measure and transfer the light information). Think of this neighbor pestering as akin to static on a radio. If you run a blender while the radio is going (humor me and pretend you have an actual radio that still gets an analog signal) that electrical current can cause static on the radio. And a mean margarita.

Noise is Not Good

That ‘static’ causes noise when the camera computer gets all the info from every sensor and things aren’t 100% as they should be. There are a couple of types of noise and I’m not going to get into all of them.

Noise (not grain, like in the film days) is ugly, should be shunned and possible fed to wolves. Noise is caused be the increased sensitivity required to capture lower levels of light. And it captures the electrical interference from neighbor sensor. Remember your keyboard? 10-30+ MILLION of these suckers in that space. Not a lot of elbow room.

If you want an exhaustive study of noise, Leica has a great explanation and better diagrams.

Revenge of the Stops

Guess what we call the 50, 100, 200, 400, 800, 1600, 3200, 6400, etc… of the ISO scale? Stops. If you guessed it right you get a +50 bonus (oh yes, you get to keep score).

100 is twice as sensitive as 50. 200 is twice as sensitive as 100. Finally the math gets easy! This means 100 needs half as much light as 50 for the same exposure. Ha ha ha ha….you walked right into that one.

I know, 50 to 100 is twice as much, but it needs half as much light? That’s the way it goes. Here’s the last piece of the puzzle.

At ISO 3200 the images will be brighter than at ISO 100 (if you leave shutter speed and aperture the same). High ISOs are great for fast objects and capturing action. Lower ISOs are ideal for scenic shots as they will have less noise (and typically aren’t moving fast or at all).

How Much Is Too Much?

How much noise is ok for you is something you need to discover yourself. For me and my Canon 7D Mark II I’m ok with 1200 at times, but the lower the better. It also matters on the subject as dark solids can tend to show noise more readily than mixed light color areas. Try to use the lowest ISO you can for the most noise free images.

Let’s put them all together on one card.

You are welcome to download the image as long as it is only used for personal information. You may not do commercial things with it, post it on the internet without a link back here or do other things I do not like. Or print it to keep with you for reference sake. You may print an extra copy to send to your Mom. She called today and is wondering why you never write letters any more.

Some High ISO Noise Examples

Click on an example below to view them nice and large with all the ugly noise you would want.

Costa Rica – ISO 10,000

Phobjeka Valley – Bhutan – ISO 12,800

Smithsonian Museum – Washington, D.C. – ISO 51,200

Utah – Mesa Arch – Canyonlands National Park – ISO 12,800

What is your ISO limit? Is it 1600 or 6400 or what?

Here’s an experiment to help you learn your own limit from the comfort of your home: ISO Limits Of Your Camera

Wahoo! We’re Done With The Exposure Triangle!

And that is the end of the Exposure Triangle. Shutter Speed affects blur. Aperture affects Depth Of Field. ISO controls the overall sensor sensitivity to light. They all need to be in balance to make a proper exposure.

But not before a Pop Quiz!! How many stops of light difference is there between 1/60 f/8 ISO 400 and 1/15 f/8 ISO 100? And how many difference between 1/60 f/8 ISO 400 and 1/15 f/8 ISO 3200?

The answer will be revealed tomorrow.

Up Next: Photography Jargon

Questions? Pop ’em like Pez in the comments section below. or email me at peter@peterwestcarey.com.

Photography Basics – A 43 Day Adventure, and its companion 40 Photography Experiments, are series written by professional photographer Peter West Carey. The series are designed to unravel the mysteries of photography, helping you can take better pictures. Subscribe here to receive all the updates and bonus material. Your comments are always welcome.

If you enjoy the series, consider learning photography first-hand on a professionally led international photo tour in Nepal or Bhutan. More information can be found at Far Horizon Photo Tours.

October 9, 2018
What Is An Aperture? – Photography Basics
Welcome back from the weekend! As a refresher, we are starting in on the The Exposure Triangle and Friday started with Understanding Shutter Speed.

What is an Aperture?

Aperture affects Depth Of Field. Do you still hate math? You might hate it more after this. Check it out.

Yeah. That’s Depth Of Field (from Wikipedia). There’s also the Circle Of Confusion. And all that is likely to make your head spin, so let’s break it down to simple terms.

Getting back to yesterday’s diagram:

The aperture on a camera is actually located in the lens. It is behind all the elements (the pieces of glass or plastic in the lens that do the focusing of light) and closest to the camera.

Before light leaves the lens, it passes through the Aperture. Most Apertures are made up of a number of blades which effectively make a smaller and smaller hole for the light to pass through. Why? Because it will increase Depth Of Field as it does so. It looks, more or less, like this:

From left to right, the aperture is open, closing, closed as far as it will go.

Most smartphones and drones have a fixed Aperture, meaning you can’t change the value or close the Aperture. Although things are changing with those cameras. The same is true with action cameras, but most mirrorless cameras have an adjustable Aperture.

Let’s Diagram How Aperture Works

Now, it doesn’t actually block the field of view as it might seem, it’s blocking light that isn’t coming into focus at a given plane. Let me try a diagram.

Light comes from a source, let’s say the sun, hits the bunny and bounces into the camera lens. In this simple diagram, one element in the lens is then moved front to back to focus (just like a magnifying glass). That’s the Focusing Lens in the diagram. Focus means the light from the bunny hits the plane of the sensor evenly (front to back), in a two dimensional way.

Another horrible way to think of focus with a lens is frying ants with a magnifying glass. I know, it’s gross, but if the glass was too far away, the light would not be properly focused and no ants would be harmed.

In this diagram, the aperture is open all the way. This focus is only good for the bunny, for how far away the bunny is from the camera. The Bunny Plane™ if you will.

More Diagraming

If the bunny moves or the camera moves or the focus is changed, this happens.

Because the focal plane is not on the sensor and is way behind behind the camera, the bunny will be blurred. Bad for you and the bunny.

It’s a fact that you can only focus on one plane at a given distance with your lens. Maybe that bunny is 15 feet away. In the top diagram the focus was set to 15 feet. In the bottom one, maybe it was set to 20 feet and thus, the focal plane (Bunny Plane™ = focal plane) was off of the sensor.

IMPORTANT NOTE: ALL of the bunny light is still hitting the sensor. It is just hitting it while being focused on a plane past the sensor. If the light (in these diagrams) is not focused on the plane of the sensor, it is blurred.

Different Distances and Focal Planes

“Well then,” you may be asking, “how the heck do I get things in focus that are different distances away from the camera?”

Aperture! First let me show you what it looks like having different objects at different distances as the light comes into your camera.

The camera lens can only focus on one distance or plane. You chose to focus on the Bunny Plane™ in this example. Who wouldn’t?

In this case then, the tree and the Yeti, being further back and having the aperture open all the way, do not have their light focused on the correct plane of the sensor. They come out blurred. Now let’s use the aperture and close it a bit. I’m going to remove the bunny for a moment. Don’t freak out, the Yeti doesn’t get her.

Here is what the light coming from the tree looks like. Same as above. Now, close the aperture…

With the aperture partially closed, as represented by the increased darkness around the edge of the aperture, that ‘extra’ light is cut off and only the light that will come to a high focus is let in. From this point forward, the tree will continue to be in focus. This can be a hard concept to illustrate in two dimensions.

When you close down the Aperture, you cut out the extra light from an object that was not going to hit the sensor in sharp focus and are attempting to only let in the light that will be in focus.

More Stopping

Aperture settings are often called f-stops. Remember when I mentioned stops yesterday? These function the same way, letting in half as much light as the f-stop goes from one setting to another and doubling the amount of light hitting the sensor when changed in the opposite direction.

In the case of the Aperture, the sequence looks like f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32, f/45 and so on. The f-stop number is a function of the lens focal length and the size of the hole the Aperture makes (which is the same concept as how your pupil works, by the way). The smaller the Aperture/pupil size, the less light. Because we are working with fractions again, and the equation looks like it does at right (thanks Wikipedia): the higher the number, the less light.

The higher the f-stop number, the less light and the greater the depth of field.

Depth of Field

Depth Of Field (DoF) simply means the the number of planes (or things, if that makes it easier), front to back, that can be in focus.

Written another way DoF = amount of stuff, front to back, in focus.

If we focus on the bunny and use f/1.4 for instance, the Depth of Field might only be a foot. Meaning from the point you are focused, maybe the bunny’s nose, the only objects that will be in focus will be .33 feet in front of that point and .67 feet behind that point = 1 foot total. (Side Note: This 1/3 in front and 2/3 behind ratio is true of your eye as well, but that’s a lot more boring physics than we need here)

Now change the aperture to the next stop, f/2 (which, as it is another stop, lets in half as much light) and you might have increased the Depth Of Field to 2 feet. .66 feet in front of the nose and 1.34 feet behind it. Can you see how more and more things will come into focus as the f-stop is increased?

Here’s another piece of the puzzle:

The person at top is to represent portrait work, where a wide open aperture and its shallow depth of field is often desired to help the person stand out from the background. The mountain scene at the bottom represents a time when you might want many things, front to back, in focus and thus a smaller aperture is desired.

Rarely do you shoot at the extremes, so in reality that portrait might be at f/4, for instance and the mountain scene will be at f/11 maybe.

Keeping Balance

While changing to a higher f-stop number does give a greater Depth Of Field, it lets in less light. What does that do to the Exposure Triangle? It means either Shutter Speed needs to change to compensate for a good exposure, or ISO does.

Knowing what you do about Shutter Speed and how it works with stops, can you now see how if you change the Aperture by one stop darker, you need to change the Shutter Speed by one stop more light? (We’ll get to ISO tomorrow, for now we’ll keep it simple with Shutter Speed and Aperture.)

It’s those Teeter Totters Of Doom in action! If Aperture goes one way to make the Depth of Field deeper, then the Shutter Speed needs to go the other way to compensate.

An Example

What does this look like in the real world? Here’s a series shot of things I found already on the floor in my house. Each object is about 6″ away from the one in front of it. Focus is locked on the golf ball in all shots. Click on a picture for a larger image.

Aperture f/5.6 Shutter Speed 1/160

Aperture f/9.0 Shutter Speed 1/40

Aperture f/14 Shutter Speed 1/15

Aperture f/36 Shutter Speed 1/3

Can you see how you more and more of the objects (and dirt on my floor) come into focus as the Aperture gets smaller and smaller (remembering that as the aperture itself gets smaller, the f/ number gets bigger)? Do you also notice what happens to the Shutter Speed? It gets slower and slower to let in more light to compensate for the aperture.

Experiment Time

Whew! I know that is a lot to take in and it is one of the harder topics for people to grasp. To make it very basic: Aperture affects Depth Of Field.

And with all that reading, it’s time to put it into practice!! Here is an assignment for you to try at home to help reinforce the ideas of Aperture and Depth Of Field:
- Depth Of Field – Changing Aperture
Tomorrow we dive into the last part of the Exposure Triangle: ISO.

Questions? Pop ’em like Pez in the comments section below. or email me at peter@peterwestcarey.com.

Photography Basics – A 43 Day Adventure, and its companion 40 Photography Experiments, are series written by professional photographer Peter West Carey. The series are designed to unravel the mysteries of photography, helping you can take better pictures. Subscribe here to receive all the updates and bonus material. Your comments are always welcome.

If you enjoy the series, consider learning photography first-hand on a professionally led international photo tour in Nepal or Bhutan. More information can be found at Far Horizon Photo Tours.
October 8, 2018
Understanding Shutter Speed – Photography Basics

Now that you know how your camera, any camera, works, let’s get into the nitty gritty of the The Exposure Triangle.

Shutter Speed

NOTE: Even if you don’t have a physical shutter in your camera (smartphone, action camera, drone and mirrorless owners), this information is vital for taking great photos.

Shutter Speed affects blur. Get that into your noggin right now.

View of market area – Kathmandu, Nepal

It does some other things, of course, but the biggest effect it has on the average photo is stopping motion, or not stopping motion, depending on how it is used. Motion can be in front of the camera or the camera itself moving. Of course, blur will occur if things aren’t in focus, but let’s assume everything is in focus.

Shutter Speed is the speed at which the shutter inside your DSLR (not smartphones, drones, mirrorless or action cameras as they scan of the sensor from top to bottom instead, which functions the same, essentially) opens and closes to let in light. That amount of time is expressed as, well, time. 1″ is one second of open shutter. 5″ is five seconds of open shutter. 1/60 is one sixtieth of a second of open shutter.

I know some of you out there hate math, but it will come into play regardless. Here’s one example. Which let’s in more light, 1/10 or 1/100?

Answer: 1/10. Remember: Larger denominator (that number on the bottom of the 1/ fraction) = less light = faster shutter speed. 1/10 lets in more light that 1/100 than 1/1000. There’s a diagram at the bottom to help with this memorization.

I know that is over simple for those that enjoyed or at least ‘got’ math, but I have taught this enough to know many out there outright hate math.

The Physical Shutter Inside Your Camera

So where the heck is this shutter and just how does it work? Let’s look at, what is loosely called, a diagram of a camera:

When the camera shutter release (aka: The Button) is not pressed, this is how DSLR camera stays. Light comes in through the lens, is focused, passes through the aperture, bounces off the mirror, bounces twice off the pentaprism and then through the eyepiece so you can see it. Do you notice the shutter is in a bunch of pieces? This is to represent the two curtains of the shutter; front and back. I used four pieces but yours might have more or less. For the curious, here’s a picture looking in through the front of my camera.

That bright thing at the top is my thumb holding the mirror up and out of the way. What you are looking at is the front curtain of the shutter. Notice the individual blades (four of them). Behind this curtain is an identical curtain. When you press the shutter release all hell breaks loose.

The mirror flips up out of the way (without the aid of my thumb). While it is doing that, the shutter curtains performs a little dance that looks like this:

That’s how the shutter functions. When things get going reall fast, the second curtain follows the first curtain, only letting in a smidge of light to expose the sensor for the set time, such as 1/200th of a second. Like so:

The faster the shutter speed, the more action in front of the camera is stopped. The slower the shutter speed, the more things in front of the camera can blur. To break blur down a bit further, let’s think about how you see things.

How You See Things

You see things because light bounces off of them and hits your eye (please don’t make me draw an eye…..you won’t like it, but it is a lot like a camera). You aren’t seeing the bunny, per se, you are seeing the light bouncing off of it. This plays into White Balance, covered later.

Blur is represented in the camera when light bounces off of an object and, because of a slow shutter speed where light is allowed to hit the sensor for (relatively) long periods of time, hits the sensor in two or more spots. (Again, I’m only talking about movement blur, not out-of-focus blur.) If that shutter is left open for, say, one second as in the first shutter diagram, the bunny can move a lot and light will bounce off of it and hit different parts of the sensor. Multiple images so close that sharp edges look blurred.

Here’s an example of moving the camera with the shutter open for 1.6 seconds.

Now this isn’t necessarily bad. It can be used for some cool effects and we’ll cover Pan Blur, Light Trails and long exposures with flash later on in the month.

For instance, hold the camera steady (or use a tripod) and let the action move for five seconds, like this scene from Cusco, Peru, and you get some interesting light trails.

Does This Make Sense?

Moving objects need a faster shutter speed (1/1000 is faster than 1/60 is faster than 1″) to be able to make them appear sharp and not blurred. This is also true of you, the camera holder, moving. If you aren’t still and you move the camera while shooting and the shutter speed is slow, say 1/10, then things will blur. We’ll go over How To Hold A Camera later as well.

Nice, crisp stopped action:

A couple playing with their dog on beach at sunset, Whidbey Island, Washington, USA Shutter Speed: 1/400th of a second

An osprey dives for its lunch. Shutter Speed: 1/8000 of a second

Golden Retriever dog shaking off water after swimming in pool Shutter Speed: 1/1600th of a second

An important thing to know about shutter speed is it is linear in the amount of light hitting the sensor. Meaning 1″ is twice as fast as 2″. 1 is half of 2. 1″ lets in half as much light as 2″. 1/2″ lets in half as much light as 1″. 1/4″ lets in half as much light as 1/2″. 1/8″ lets in half as much light as 1/4″. 1/15 (there is some rounding in cameras these days) lets in half as much light as 1/8″. 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000, 1/2000, 1/4000 to the highest most cameras will go of 1/8000.

Stop Now, Wait A Minute

Each of these halvings of light (or doubling of light if you go the other way on the scale) is called a stop. A stop is a very important concept and it will come up again and again.

In this case, going from 1″ to 1/4″ is two stops less light. That is, 1″ to 1/2″ was half as much light (1 stop) and 1/2″ to 1/4″ was half again as much (1 stop) = 2 stops. Those good with math can just divide or multiply the fractions by 2 for each stop of light.

Pop Quiz: How many stops less light is there between 1/60 and 1/1000? Use the scale above to help. I’ll reveal the answer tomorrow.

Now then, before we wrap this up, below is a piece of a puzzle which will be revealed next week. It’s meant as a quick reference and helps some people remember their shutter speeds and what they do. The arrow represents more light hitting the sensor down to less light hitting the sensor.

If you want to take pictures of slugs, you can get by with slower shutter speeds. If you want to take pictures of bunnies on scooters, you’ll need faster shutter speeds. The word Blurry is to indicate if you are hand holding a camera, or if there is movement in front of the camera, your photo is likely to be blurrier at the top of the scale. Of course, this scale extends past both 1″ and 1/250

Wrapping It Up

I hope you have enjoyed this first week of posts. On Monday we’ll start up again with What is an Aperture?

Until then, I have a Weekend Experiment for you to try. These experiments are changes to go out and practice and learn firsthand. The first experiment is about Speed & Light. Give it a try and post your results.

Questions? Pop ’em like Pez in the comments section below. or email me at peter@peterwestcarey.com.

Photography Basics – A 43 Day Adventure, and its companion 40 Photography Experiments, are series written by professional photographer Peter West Carey. The series are designed to unravel the mysteries of photography, helping you can take better pictures. Subscribe here to receive all the updates and bonus material. Your comments are always welcome.

If you enjoy the series, consider learning photography first-hand on a professionally led international photo tour in Nepal or Bhutan. More information can be found at Far Horizon Photo Tours.

October 5, 2018