Confused by some verbiage somewhere?  Check out all the terms below to get things cleared up.

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Amp Glow

The added noise in a photo (usually large, red discolored blobs) due to excessive heat generated by long camera usage.  Usually seen in long exposures at night.

Aperture

The diaphragm in your camera’s lens which allows light to enter the camera.  Changing the size of the aperture will change the depth of field (DOF) of a scene as seen by the camera: a smaller aperture will result in a deeper DOF; a larger aperture will create a shallower DOF.  Aperture is represented by an f-number or f-stop, which is displayed on the camera as f4, f8, f11, etc.  A factor of two change in the f-stop represents a factor of four change in the aperture size, which is equivalent to a 2-stop change in exposure.  For example, with all other settings the same, a photo taken at f/4 is four times brighter (two stops = 2^2 = 4) than one at f/8.

Aperture Priority Mode

A control mode on a camera where the user sets the desired aperture and the camera adjusts shutter speed accordingly in order to maintain the correct exposure.  Useful in situations where depth of field is the most important consideration.

Auto-Focus

When the camera focuses the lens automatically.

Barrel Distortion

Distortion caused by a lens such that lines which should be straight in a photo appear to bow out away from the center of the image.

Blown-Out

When the highlights, or brightest parts of an image, become so bright they are shown as completely white.

Body

The camera itself.  I.e. the part with all the controls, displays, and viewfinder.

Bokeh

The out-of-focus area of a photograph and its aesthetic quality.  Generally, smoother, rounder, and softer bokeh is considered better.

Bracketing

Bracketing is the process of shooting multiple images of the same scene while varying one parameter from shot to shot in order to select the best photo after the fact.  Exposure is the most common parameter to be adjusted while bracketing (usually done by varying the shutter speed).  Exposure bracketing is very useful for digital blending and High Dynamic Range (HDR) processing.  Bracketing is not limited to exposure however, as one can bracket white balance, shutter speed, aperture, or focus as well.

Center-Weighted Metering

Using the central portion of the camera’s light sensor as the control point for determining exposure.  Many cameras have a setting to adjust how large this center-weighted area is.

Chromatic Aberration (CA)

Also known as fringing, chromatic aberration is the effect caused by different wavelengths of light refracting differently in the glass of a lens.  Often seen as magenta or cyan halos in areas of high contrast in photos, CA is generally more of a problem for zoom lenses rather than prime lenses.

Circle of Confusion

A physical dimension above which point-sources of light degrade into circles due to being out of focus.  In other words, the acceptable limit of sharp focus.

Composition

The layout, placement, angle, and perspective of a scene within an image.

Continuous Focus

A version of auto focus where the camera continuously focuses the lens as the distance between the camera and the subject changes.

Crop Factor

The relative size of a camera’s image sensor compared to a full-frame sensor or 35 mm slide.  Most digital SLRs are a 1.5 or 1.6 crop factor, meaning their sensors are 1.5 or 1.6 times smaller than a full frame sensor.  This has the added effect of increasing the relative focal length of lenses on cropped-sensor cameras. For example, an image which covers the entire sensor on a cropped camera will only cover 2/3 of the sensor on a full frame camera.  In order for the image to cover the entire full-frame sensor, the camera lens would need to be zoomed in 1.5 times farther.  Therefore, a 200 mm lens on a cropped-sensor is approximately equivalent to a 300 mm lens on a full-frame sensor.

Depth of Field

The term which describes how deep focus runs in an image.  Images with a shallow depth of field have very limited areas in focus whereas images with a deep depth of field can be in focus from front to back.

Digital Blending

See Digital Graduated Neutral Density Filter.

Digital Graduated Neutral Density Filter

A digital blend between two or more exposures of the same scene in a way to compress the dynamic range of the scene.  Mimics the effect of a Graduated Neutral Density filter.

Dynamic Range

The range of brightness values in a photograph or scene, ranging from pure black to pure white ( i.e. very dark shadows and very bright highlights).  Nature scenes often have a dynamic range  greater than that a camera can capture, necessitating the use of filters or digital processing techniques in order to compress the dynamic range of the scene to a capturable level.

EXIF

Data recorded by the camera and viewable with most image-viewing software which gives the camera settings (such as shutter-speed, f-number, ISO, white-balance, flash settings, etc.)  for any given image.

Exposure

How bright or dark a photo appears.

Exposure Compensation

Manually overriding the camera’s default exposure setting in order to purposefully render an image brighter or darker than it would be by default.

F-number

The indicator of the aperture setting on a camera.  Larger f-numbers indicate smaller aperture sizes.  The relationship between f-numbers and aperture is such: when the f-number doubles, the aperture size decreases by a factor of four.  For example, at f/8, the aperture is four times larger than at f/16.

F-stop

See F-Number

Fast

An adjective which describes a lens with a relatively wide maximum aperture.  For example:  f/2.8

Fill Flash

Flash that is used to fill in deep shadows in backlit subjects.  Fill flash can also be used to brighten a dark foreground in scenes with a high-dynamic range.

Film

I have no idea what this is.

Filter

A thin piece of clear, colored, or darkened resin or glass which attaches to a lens in order to modify the light entering the lens by colorizing it, darkening it, etc.

Focal Length

An attribute of lens generally used as an indication of how wide a field of view the lens has.  Smaller focal lengths are used for wider lenses.  For example, a wide-angle lens with a focal length of 12 mm has a field of view of around 100 degrees, whereas a telephoto lens at 200 mm might only have a field of view of 12 degrees.  In practical terms, this means the 200 mm lens is much farther “zoomed in” than the 12 mm lens.

Focus Point

Seen when looking through a camera’s viewfinder, a focus point is a selectable rectangle the camera will use as a control point when determining what to focus on.

Frame

1) As a verb, frame means to compose an image: e.g. “Do you like how I framed this shot?”

2) As a noun, frame means the area seen through the viewfinder and captured by the image sensor: e.g.  “If I stand here will I be in your frame?”

3) Frame can also simply mean a photo: e.g. “I went out shooting tonight and shot 300 frames.”

Fringing

See Chromatic Aberration

Full-Frame

Can refer to an image sensor or a camera with an image sensor which is the same size as a 35-mm piece of film.  In contrast to most digital SLRs which have image sensors 1.5 or 1.6 times smaller than 35 mm.  The larger sensors give higher image quality and less noise and are therefore generally found in “pro-level” digital SLRs.

Glass

Another word for a lens.  E.g. “Wow, that’s a nice piece of glass you’ve got there.”

Graduated Neutral Density Filter

A colorless filter which is dark on one half and clear on the other half.  These filters are used in scenes with high dynamic range in order to compress the dynamic range to something the camera can capture.  For example, by placing the dark part of the filter over the sky (as seen by the camera), a photographer can make the sky 2 or 3 stops darker while leaving the brightness of the foreground unaffected.

High Dynamic Range

1) A dynamic range greater than that the camera can capture.  For example, a scene which contains a full range of brightness values from very dark shadows to very bright highlights has a high dynamic range.

2) High Dynamic Range can also refer to a specific type of digital processing in which multiple exposures of the same scene are captured through exposure bracketing and combined via specialized software in order to display the maximum amount of detail in both the shadows and highlights in an image.

Highlights

The brightest parts of an image.  If the highlights are so bright that they are rendered as completely white, they contain no detail and are said to be “blown-out.”

Histogram

A graphical display of the range of brightness values in an image.  The histogram indicates if an image is too dark or too bright, or has excessive shadows or excessive highlights.

Hyperfocal Distance

Hyperfocal distance can be thought of as the distance where you should focus your camera so that you get maximum depth of field.  More technically, it’s defined as the point where if you are focused there, your scene will be in acceptably sharp focus from half that distance to infinity.  Hyperfocal distance changes based on focal length and aperture according to the formula: H = L^2 / (c * F) + L, where L is focal length, F is f-number, and c is the acceptable limit of sharp focus (0.03 mm is a typical value).

ISO

The setting on your camera which indicates how sensitive to incoming light.  Lower ISOs mean the camera is less sensitive.  Higher ISOs allow for fast shutter speeds in low light, but shooting at high ISO introduces more noise into an image.  The relationship between ISO values is straightforward: for example, ISO 200 is twice as sensitive as ISO 100.  ISO 400 is four times less sensitive than ISO 1600.

Long Lens

See Telephoto Lens

Long-Exposure

A term used to describe photos which have a shutter speed much longer than a fraction of a second.  While there is no hard limit as to what is “long exposure” and what isn’t, long exposure photo generally have shutter speeds ranging from a few seconds, to a few minutes, to a few hours.  This allows for the capture of stars trails, moving car lights, the motion of clouds, and perfectly smooth and uniform water, among other things.

Macro Lens

A lens generally used for taking extreme close-ups of small subjects, such as insects or flowers.

Manual Focus

A method of focus where focus is selected manually by the photographer.

Manual Mode

A control mode on a camera where the user sets the aperture, the shutter speed, and ISO value.  The camera will not compensate for any user settings.  Useful in situations when you want absolute control over all aspects of a photo.

Matrix Metering

Using an array of points from all over the camera’s image sensor in order to determine proper exposure for a scene.  Gives an averaged value for exposure and prevents large changes in exposure if the camera’s focus point moves from something dark to something bright.

Megapixel

A standard measure of camera resolution.

Monopod

A support for a camera made of one single leg.  Helps remove camera shake and jitter but allows camera to pan and rotate quickly.  Useful for photography of fast-moving subjects using long lenses, such as sports or wildlife photography.

Neutral Density Filter

A dark filter with completely neutral color designed to cut the amount of incoming light entering a camera.  Useful for increasing shutterspeed.

Noise

Also known as “grain,” noise is tiny discolored dots in a photo which can destroy detail and prevent color gradations from looking smooth.  Noise is caused by shooting at high ISOs, shooting in low-light conditions, using long-exposures, and post-processing images.

Pincushion Distortion

Distortion caused by a lens such that lines which should be straight in a photo appear to bow in towards the center of the image.

Point and Shoot Camera

Your typical pocket-sized digital camera.

Polarizing Filter

A filter designed to polarize the light entering a camera in order to cut haze, reflections, help color saturation, and make the sky a richer blue.  Polarizers work best when shooting 90 degrees off-axis from the sun.

Prime Lens

A lens with a fixed focal length.  Because the optics are optimized for one focal length, prime lenses are generally sharper, clearer, and possess less distortion than zoom lenses.

Reciprocity Failure

A given exposure can generally be obtained through many combinations of aperture and shutter speed.  For example, a shutter speed of 1/100 at f/8 will give the same exposure as 1/200 at f/5.6 and 1/400 at f/4.  This is called reciprocity. However, in low light situations this reciprocal relationship between shutter speed and aperture breaks down.  This is reciprocity failure, and must be compensated for by increasing shutter speed for a given aperture past what this relationship would normally dictate.

Sensor

The actual light-recording part of the camera.  The digital analog to a piece of film.

Shadows

The darkest parts of a photo.  Shadows so dark they are shown as pure black in an image contain no detail and can be said to be “lost.”

Sharp

Sharp means in focus.  The sharper an image is, the more fine detail can be seen in it.

Shutter Priority Mode

A control mode on a camera where the user selects a desired shutter-speed and camera compensates by changing aperture in order to maintain exposure.  Useful in situations where shutter speed is the most important consideration, such as panning shots.

Shutter Speed

An indicator of how long your camera’s shutter is open when you press the shutter button.

Single Focus

A method of auto-focus where the camera focuses on the subject and maintains focus at that distance even if the subject moves.

Single Lens Reflex (SLR Camera)

A camera designed so that the photographer looks out through the camera lens and sees the scene exactly as it is captured by the camera.  Can be used with interchangeable lenses.

Soft

When something that should be in focus is slightly out of focus, it is said to be soft.  E.g. “These rocks in the foreground look a little soft, I wish they were in sharper focus.”

Spot Metering

A method of using the camera’s current focus point as the control point for determining exposure.

Stop

A change in exposure by a factor of two.  I.e. a photo that is twice as bright as another photo is 1 stop brighter.  A photo that is four times brighter is 2 stops brighter.

Stop Down

To increase the f-number in order to increase depth of field or improve lens performance.

Telephoto Lens

A lens designed for taking pictures of far-away subjects or for magnified shots of near subjects.  Some telephoto lenses can also be used as macro lenses.

Tones

The color and brightness of an image.

Tripod

A stabilizing support for a camera which has three legs and a head to which the camera is mounted.

UV Filter

A completely clear filter which is often screwed onto the front of a lens in order to protect the actual lens glass from damage and contamination.

Viewfinder

The part of the camera that the photographer looks through in order to compose an image.

Vignetting

The gradual darkening of an image near the edges of the image.  Vignetting can be caused by physical objects, as well as the optics within a lens.  While generally undesirable in landscape photography, vignetting can be used to great effect in wildlife and portrait photograph by drawing the viewer’s attention to the subject at the center of the photo.

Wide Angle Distortion

A shift in perspective caused by wide angle lenses such that objects become stretched as the near the edge of the field of view of the lens.  For example, a  spherical ball viewed through a wide angle lens can appear elliptical if it’s near the edge of the field of view of the lens.

Wide Angle Lens

A lens designed to have a very wide field of view.  Very useful in landscape photography.

Wide Open

When a lens is set to its maximum aperture (smallest f-number), it is said to be wide open.

Zoom Lens

A lens which can transition through a range of focal lengths in order to provide a great number of options for composition.

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Any terms I’m missing?  Any you want described?  Leave a comment or send me an email.

The last major tool we have in our bag as we look for creative freedom is something called White Balance (WB).  White balance is your camera’s way of compensating for different colors of lighting in your photos, but in order to really understand it, we need to first take a look at your eye.

Simply put, your eye is incredible.  (Note that when I say “eye” here, I am really referring to your eye-cum-brain; i.e. your entire image-processing center).  It has signal processing capabilities your camera can only dream of.  One of the most amazing things your eye can do is to maintain color consistency in different kinds of lighting.  What I mean is, if you take an American flag (for example) into any kind of lighting: bright sunlight, shade, fluorescent, incandescent, halogen, sodium-vapor, or whatever, you will see the colors of that flag as red, white, and blue.  The truth is that the actual color of light reaching your eye is almost guaranteed to NOT be red, white, and blue.  For example, if you are looking at the flag underneath fluorescent lights, the stripes that you perceive as white are actually the tiniest bit green.  If you’re out in broad daylight, the stripes might be faintly yellow, and if you are under sodium-vapor lighting, they will be positively orange.  This is because all objects can only reflect the light incident upon them, be it orange, yellow, or green.

Take a look at these flags.  Each is shown under slightly different lighting conditions.  Take a few pieces of paper and block out all but one of the flags.  It becomes almost impossible to see the flag as anything except red, white, and blue.  It’s only when it’s shown in comparison to the other flags that the color casts become clear.  It just so happens that your eye is so good at tuning out these color casts that you don’t even notice them.  You expect the flag to be red, white, and blue, and so you see it red, white, and blue.

Your camera, however, has no expectations of what colors things are, and so it only records the exact colors of light that are actually hitting the sensor.  That means if you take a picture of a white sheet under different lighting conditions, in your final image it’s going to appear blue or magenta or orange . . . really any color except white (unless of course you are shooting under pure white light).  Here’s the important part:

The White Balance control in your camera is designed to compensate for these color casts in order to make white objects actually appear white in your images.

Your camera likely has a number of white balance settings in order to compensate for color casts in the most common shooting environments, from daylight, to shade, to flash, to incandescent lighting.  It also probably has an auto white balance setting, which I’ve found works pretty well much of the time, but it isn’t a silver bullet, so it’s very important to learn when to manually adjust your white balance.  Getting the right white balance manually is usually as simply as selecting the right setting on the camera: if you’re in shade, select the shade setting; if you’re out in a nice sunny day, use the sunlight setting, and so on.   Obviously, these settings are designed to compensate for the conditions they describe.  Incandescent lights are very orange in color (what we photographers like to call “warm”), so the incandescent setting on your camera compensates for this by making the image more blue.  Conversely, shade is usually very blue lighting (or “cool” as we say), so the shade setting warms your image up to remove the blue color cast.

However, sometimes you’re not in such a cut-and-dried situation, so what do you do?  Never fear!  Most likely your white balance settings are arranged on your camera in order from warmest to coolest (or vice versa).  So if you’re in a situation where you’re not actually sure what white balance to use, but you know you’re not happy with an image because it looks too warm, all you have to do is flip down to the next WB setting and your image will cool off.  Or if it looks too cool, turn the dial the other way and warm it up.

Of course, WB can also be used for creative effect.  For example, shooting a sunset with “cloudy” white balance will add a bit of richness and color to your image.  The other settings can be used to make an image look completely orange or completely blue.  How far you take your color casts is up to you.

And that’s been the whole point of this entire series of “Getting off Auto Mode” posts: once you understand how your camera works, you can use it creatively to make the images you want to make.

That’s the end of the camera-oriented posts.  Next up we’re going to be taking a look at the other side of producing a masterful nature photograph: Composition.

Next: Composition 101

Previous: Getting off Auto Mode, Part 5 of 6: Exposure Revisted

Light Loss.

Blueing of photos.

This page is under construction.

This page is currently under construction

This Page is under construction

This page is under construction.

In simplest terms, composition is how the scene is placed in your image.  How zoomed in or zoomed out you are, whether your are up high or down low, the angle you shot from, what is in your foreground, midground, or background.  The composition is what creates the impact and tells the story of the image.  In my opinion, composition is the most difficult part of photography, but there is a science to the art of it and once you’ve learned the basic rules of thumb you’ll be creating beautiful compositions in no time.  Here are some of the most important ideas in composition:

Focal Length

Fill the Frame

Rule of Thirds

Get Rid of the Sky!

Leading Lines (Foreground, Midground, Background)

Simplify and De-clutter

Perspective is Everything

Lighting is Everything

Balance

Level Your Horizons

Just Because It’s a Wolf Doesn’t Make It a Good Picture

Focus on the Eyes

This page is still under construction, more to come soon . . .

Next: Post-Processing 101

If you’ve been following this series from the beginning, by now you’ve learned everything there is to know about the three basic controls of your camera. You know that you can lengthen your shutter speed to add motion blur to your shots, or shorten your shutter speed in order to freeze time.  You can open your aperture wide to create a shallow depth of field, or you can stop it down to create a deep DOF.  And lastly, you can increase your ISO to make your camera more sensitive to low light, or you can reduce your ISO to help get rid of noise and boost your image quality.

You also know that changing any of these three parameters has an effect on your image’s exposure: for example, opening the aperture lets in more light, so our camera compensates by shortening the shutter speed so as not to blow out the image.  In other words, every decision we make regarding aperture, shutter speed, and ISO is a compromise which is driven by the dominating need to fill our photo up with the “right” amount of light.

But what does that mean exactly?  What is the “right” amount of light?  So far in all of our experimentation the camera has determined what the “right” amount of light is and adjusts itself accordingly based on the decisions we make.  So how does the camera do this?  And how can we change it if we don’t like what the camera is doing?  After all, just based on personal tastes, some people will prefer darker images and some will prefer lighter ones.  There is no universal “right,” even though our camera seems to think so.  This post will take a deeper look at exposure so that you can control your camera to get the right amount of light for you.

First things first: we’ll take a look at exactly how the camera decides what the right amount of light is:  Your camera has a built-in light meter which measures how much light is entering the lens and compares that to a standard reference point called “middle gray,” which is the point perceptually halfway between black and white.  In fact, your camera not only compares the incoming light to middle gray, it actively tries to make the incoming light match middle gray as closely as possible, in terms of brightness.  In other words, no matter how bright or dark your scene is, your camera wants to let just the right amount of light in to achieve that middle gray brightness.  That’s why in bright scenes you will have short shutter speed and small apertures, whereas in dim scenes your camera will tend toward wide apertures and long shutter speeds.  What this means then is that the camera is actually kind of stupid: it’s trying to take things that are bright and make them match this middle gray, and it’s trying to take things that are dark and make them match this middle gray.  You can do a quick experiment to prove this by taking a picture of a white wall; if you’re on auto mode or any of the “priority” modes, the white wall will actually come out gray.

This page is still under construction.  More to come soon . . .

Next: Getting off Auto Mode, Part 6 of 6: White Balance

Previous: Getting off Auto Mode, Part 3 of 6: Understanding ISO

Heading back to the bathtub example, I mentioned that there are three things we can do in order to fill up our bathtub with the right amount of light: 1) open the faucet a lot or a little.  2) leave the tap running for a long time or a short time.  3) Change the size of our bathtub.  The first two have been covered in detail in the understanding aperture and shutter speed posts.  Now it’s time to talk about number 3, which on our camera takes the form of changing the ISO.

In simplest terms, ISO is how sensitive your camera is to the incoming light: the higher the ISO, the more sensitive the camera is, and vice-versa.  What this means in real terms is that if you are at a higher ISO you can give your photos the proper exposure with less light.  For example, a shot taken at ISO 400 requires half as much light to create a proper exposure as the exact same shot taken at ISO 200, and a shot taken at ISO 100 requires 16 times more light than the same shot taken at ISO 1600.  This is pretty intuitive so I’ll skip straight into why we need to adjust our ISO.

If you recall from the experimental shots in the shutter speed essay, if we dialed the shutter speed up as fast as we could, the camera would respond by opening the aperture wider and wider until it eventually got to a point where it would display something like “Lo” instead of an f-number.  This means that the camera thought there wasn’t enough light to properly expose a photo with the current camera settings.  But we just learned above that by increasing our ISO we can take a photo in less light.  This means that we can maintain a fast shutter speed in low light conditions by upping our ISO.  Neat!

An example: say we are taking a picture of a bird out in the bright sunlight.  He’s moving around and flapping his wings really fast, so we set our shutter speed to something really quick, like 1/2000 (and the camera automatically opens up our aperture to let in more light).  This way we are able to freeze his motion in the image, thus adding drama and tension.  Then all of a sudden the bird flies into the shade.  We try to take a picture of him, but a quick look at the LCD shows us that the image is really dark, in fact you can hardly even see the bird!  Obviously there is way less light in the shade than out in the sun, so we need to compensate for this by changing the settings on the camera.

By now you should know there are a few things we could do.  First we could try to open the aperture.  But that won’t work here because the camera already opened the aperture as far as possible when we put our shutter speed to such a fast value.  Second, we could try to lower the shutter speed to let light in over a longer period of time.  But that won’t work here because then we won’t be able to freeze the bird in action any more; instead he’ll just be a big blur in the image.  Our only viable option is to increase the ISO so that the camera is more sensitive to the lesser amount of light in the shade.  So we bump up the ISO to 1600 and poof! now the camera can capture the image at high shutter speed and have it be properly exposed.

Unfortunately there is a trade-off when we do this: noise!  And I’m not talking about  pop music.  No, I’m talking about those ugly little discolored dots popping up all over your image:

Noise occurs primarily because the sensor in your camera isn’t perfect and there is some uncertainty in every reading your sensor takes, and subsequently some tiny variability between every pixel and the next.  At the moment it’s much less important to know where the noise comes from than to know that when we increase our ISO we also increase our camera’s susceptibility to noise.   (For a more in-depth discussion of noise, please see this post).  In other words, to get the best possible quality image, shoot at the lowest ISO available.  This is especially pertinent for landscape photographers, who are generally shooting something that isn’t moving: unless you have a very good reason to shoot at a higher shutter speeds, you should be at your lowest ISO setting.  Wildlife photographers are in a bit of a different pickle, because it may be necessary to shoot at high speeds in low light.  In this case upping the ISO can get us out of some tight spots when we don’t have a lot of light to shoot, but consider yourself warned: it does come at the price of a degraded image.

And with that summation we conclude our discussion of ISO.  In the next post in the series we are going to revisit exposure in order to tie everything we’ve learned so far together and take it all one step further, to give us maximum control over our images.

Next: Getting off Auto Mode, Part 5 of 6: Understanding Exposure

Previous: Getting off Auto Mode, Part 3 of 6: Understanding Aperture, part ii

In our previous essay, we discussed exactly what shutter speed is and how changing it changes the creative effects we can introduce into our photos.  We also saw (from the bathtub analogy as well as our own experiments) that when we changed out shutter speed, our camera was changing the aperture at the same time in order to maintain the correct exposure.  If we shortened our shutter speed, the camera increased the size of our aperture (to let a lot of light in all at once), and if we lengthened our shutter speed, the camera made our aperture smaller (to let a little bit of light in over a long period of time).  This is done in order to keep the total amount of light hitting the camera’s sensor the same from picture to picture.

It turns out that the reciprocal case is true as well: if make our aperture smaller to let in less light, the camera will lengthen the shutter speed in order to allow enough light in to “fill up our bathtub.”  Conversely, if we open our aperture all the way up to let in a lot of light, the camera will decrease the shutter speed so that the tub doesn’t overflow and overexpose the photo.

Now, understanding aperture is a little more complicated than understanding shutter speed, and this post certainly reflects that.  So if you’d like to skip all the technical gobbledygook and get right to the photo goodness, click here to jump to the next part of this post.

However, if you’d rather have a better understanding of what aperture is and what it means before you start experimenting wildly with your camera, read on!

But before we look at why we would want to change the aperture of our camera, let’s dive a little bit further into how your camera displays its aperture, because it’s slightly less straightforward than shutter speed, which is simply shown on the camera as a number of seconds.  The previous essay very briefly touched on this, but in case you missed that post, your camera shows aperture as an f-number, most commonly called an f-stop.  Typically this is shown on your camera as something like f2.8, f4, or f5, as can be seen here:

Note that in writing, f-stops are generally written with a slash, like f/4, f/16, etc.

This f-stop tells you how far open the aperture is, but what is confusing about f-stops is that the higher the f-number, the smaller your aperture is, and the lower the f-number, the bigger your aperture is.  This means that is you are at f/4, your aperture is actually open wider than if you are at f/8, and if you’re at f/22, your aperture is smaller than at f/11.  I know this seems totally backwards, but you must remember it, because understanding this is absolutely crucial to being able to control your camera to do the things you want it to.

Warning! Technical jargon ahead! Feel free to skip to the next section if you’d rather just hop into why we want to control the aperture.

The reason that the f-numbers seem so backward is that they actual represent a relative value, rather than an absolute one as shutter speed does.  The f-number that your camera displays is not the actual size of the aperture, but rather the ratio between your focal length (how “zoomed-in” you are; we’ll get into this more in the post about basic composition) and the diameter of your aperture.  In other words, f-stop equals focal length divided by diameter.  If we take a closer look at this ratio, you can start to see how the f-numbers makes sense: say our focal length is 100 mm, and the aperture is 25 mm across, this gives us an f-number of f/4 (because 100/25 = 4).  Now say our aperture is much much smaller, only 4 mm across; this gives us an f-number of f/25 (as 100/4 = 25).  So even though the f-number is much larger in the second case, the actual aperture is much smaller.

The other reason that an f-stop doesn’t represent the absolute size of the aperture is that because of the ratio above, for a given f-stop the actual size of the aperture changes as we change our focal length.  Say we set our camera to f/4, and then zoom in to 100 mm.  We already know that this means our aperture has a diameter of 25 mm.  Now if we stay at f/4 but zoom in to 200 mm, our aperture has to increase in size to 50 mm in order to maintain f/4.  This is why on some lenses your maximum and minimum f-stop changes as you zoom out; because when you’re all the way zoomed out, the actual aperture simply can’t get big enough to maintain the f-stop you want.

—————End of Technical Jargon Section————–

Don’t feel bad if you skipped the slightly technical section above; the technicals are important, but at present our time is much better spent by getting an empirical understanding of what varying our aperture means for our photography. (Hopefully you’re still reading this post, because here’s the sweet payoff):

By changing the aperture of our camera, we can control the depth of field (DOF) of our image.

Please read that sentence again because that is the meat-and-potatoes stuff behind aperture control.

Whenever our camera focuses, whether automatically or manually, objects at a given distance in front of the camera will be in focus.  However, what is neat is that objects slightly in front and slightly behind this focal point will also be acceptably in focus.  The farther an object gets from the focal point, the more out-of-focus it will be.  Now, you guys probably already know this, but hold on a sec, cuz I’m getting to the really cool part.

The “in focus” range is what is generally referred to as the Depth of Field.  And we just learned that by varying the aperture we can vary our DOF at the same time.  Meaning that by changing our aperture we can have a photo where everything in the photo from front to back is in focus, or we can take a photo where only one thing in the entire picture is in focus.  And this gives us an incredible amount of creative control over our images.

Now let’s skip to the next section to take a few experimental shots which will really help us hammer home the meaning and importance of aperture.

Next: Getting off Auto Mode, Part 3 of 6: Understanding Aperture, part ii

Previous: Getting off Auto Mode, Part 2 of 6: Understanding Shutter Speed