Definitions list

Aperture -How large the hole is when you open the shutter when you take a picture. The size of that hole will vary with your aperture. (Also known as "f-stop".) As the f-stop number gets larger, the hole gets smaller. Larger holes will allow you to gather more light and therefore achieve a faster shutter speed. The effect of aperture on your photo will be that the smaller the number, the less depth of field you get (and conversely, the larger the number, the more depth of field.) So, if you want to take someone's picture and the background is cluttered and ugly, use a small f-stop number (like f/4) to blur the background. If your subject is in front of a beautiful mountain range, however, use a larger f-stop number (like f/16) to make sure the mountains are sharp as well.

Bulb (and Bulb Cable) -A mode you can use for your shutter speed that allows exposures over 30 seconds. The camera cannot determine exposure for such shots, however, so you must time and calculate the exposure yourself. This mode requires a bulb cable, which allows you to press and lock the shutter open, then manually unlock the shutter to close it again.

Camera Shake -Blur that you get from not being able to hold the camera completely still while using slow shutter speeds in low-light conditions. The fix? Put the camera on a tripod or try to get higher shutter speeds by lowering the f-stop number or raising the ISO.

Chromatic Aberration -The color fringing you sometimes see in photos around areas of high contrast. It's often purple, red, or blue and is most often found along flagpoles, masts, or branches against a bright sky. It's usually worse towards the edges and corners of an image and is worse on cheaper lenses and/or extremely wide or telephoto lenses.

Cokin Filters -A filter system that consists of adapter rings for each different size of lenses that you have (about $12 each), a lens holder (about $15 with an adapter ring), and then you add filters that are square or rectangular and made of either resin or glass. It's bulky, but cheap to start with (if you choose resin filters rather than glass), and your best bet if you decide you want a graduated neutral density (or color) filter because you can choose where to put the transition between the light and dark portion of the filter by sliding it up and down in the holder (and even tilting it if you want to). Circular polarizers are available for the system as well.

Curves -A software tool that allows you to adjust brightness or color by curving a line that represents the tones in the photo. The results with this tool are much more controlled than with tools like Brightness / Contrast or Saturation / Hue.

Depth Of Field -How deep of an area in a photo is in-focus. Photos like this one are said to have a shallow depth of field, which just describes the fact that the background (and/or foreground) is blurred whereas photos like this one are said to have a large depth of field because everything from near to far is in-focus.

Drop-In Filter -A filter that drops into a holder in the back of a lens (rather than the front where you usually put screw-on filters). The lens you use must have a provision for this type of filter. They are usually used on large lenses that'd be expensive to by large filters for.

DSLR -A "Digital Single Lens Reflex" camera. This describes a digital camera with inter-changeable lenses that allows you to use full manual mode in order to control ISO, aperture, shutter speed, focus, and exposure and allows you to see, through the viewfinder, EXACTLY what your camera will record.

EV -"Exposure Value", when it's displayed, it's the same as an Exposure Meter, but is usually just a number rather than a graph. When you change the number, it's called Exposure Compensation.

EXIF -The data about the settings that were used to create an image that's recorded along with the image and can be read by some software or seen when you upload the photo to some photo hosting sites like Flickr. The data includes the time and date that the shot was taken (assuming it was right on the camera when it was taken), the shutter speed, aperture, ISO, focal length, the mode that was used, etc. This information can be helpful in troubleshooting shots that didn't come out as expected or for others to see when you post a photo for critique.

Exposure -How light or dark a photo is.

Exposure Compensation -Changing the value on the exposure meter to something other than "0" (normal exposure) in order to correct for an overly light or dark scene or when your subject is dramatically lighter or darker than it's surroundings.

Exposure Meter -Most exposure meters are displayed like this: [-2...-1...0...+1..+2] (although on Nikon's the numbers are reversed). What the camera believes is a normal exposure is indicated by the "0" on the graph. As the indicator is moved towards the positive numbers, the meter is showing that it believes the photo will be over-exposed (lighter than it should be). Negative numbers mean underexposure (the camera believes they'll be darker than normal). The camera's idea of "normal" can be wrong in situations where the overall scene is very light or very dark or when the subject is dramatically darker or lighter than it's surroundings.

Fast Lens -A lens with a low maximum aperture value. The lower you can set the aperture number, the more light you can get in via aperture, which will allow you to get higher shutter speeds. In English, this means that you'll be able to take shots in much lower light than you could with a regular lens (using only available light).

Filter -A thin piece of material you put in the path of the light as it enters your lens or camera to effect the resulting image. The most common kind are thin glass in a metal ring with threads on it that screw onto the front of your lens, but some go in between your lens and camera instead (ie: "drop-in" or "gel" filters), or there are Cokin style which allow you to get around having to buy the same filter in different sizes for all your different lenses.

Fish Eye Lens or Effect -Fish eye lenses are extremely wide -so wide that they (sometimes humorously) distort the objects in a photo. Here is an example of a photo that was taken with a fish eye effect.

Focal Length -How much "zoom" your lens has. It is measured in millimeters, like "50mm". On "zoom lenses" it's written as a range, like "a 17-55mm lens".

F-stop -See "Aperture".

Graduated Neutral Density Filter -A filter that's half clear and half dark so that if you have a bright sky and a dark foreground, you can put the dark part over the sky and the clear part over the foreground to even out the exposure of the two and get a good photo rather than having to choose between over exposing the sky or under exposing the foreground. Cokin filters are often recommended since you can change where the line between light and dark is in the frame whereas round screw-on filters usually have the line right down the middle, which is usually NOT where you want your horizon.

High Key -This describes a photo technique where you put your subject in front of a extremely light-colored background and set the exposure so the background be over-exposed (pure white). Examples.

HDR -High Dynamic Range photography allows you to get around the problem of your sensor not being able to record a large range of tones at once. For example: the detail on the inside of a house lit by relatively dim indoor lighting while also capturing the scene outside the window in bright sunlight. By taking several photos, each exposed for the different lighting situation in the areas of your photo, then merge them together (manually or with special software) in order to end up with a photo that more closely resembles the dynamic range of tones we can see with our eyes.

Infrared Photography -A type of photography that records infrared light instead of color light. The results make foliage come out white, blue skies come out black, and skin seems to glow as well. Requires only a special IR filter to get started, but for best results people often convert an old camera to a dedicated infrared camera. The conversion process removes the IR filter that comes on all modern cameras so that normal (fast) shutter speeds can be used. Without conversion you must use very slow shutter speeds because much of the IR light is blocked by the camera's built-in filter.

IR - Infrared, see "Infrared Photography".

Jpeg (or jpg) -A file type that's "lossy", meaning that it uses compression to make the file smaller, but that in the process it looses a tiny bit of detail in the photo. This isn't a problem the first time. I haven't found it to be a problem the second or third time either. But, the more times you save THE SAME PHOTO as a jpeg, the more detail you will loose and eventually this will effect your photo. So, if you intend to save and re-save your photo, choose a non-lossy file type such as a .png file or a TIFF.

"L" Lens -Canon's pro line of lenses. The telephoto lenses are painted white which makes them easy to spot on sports fields, etc. Their wide-angle and normal "L" lenses are indicated by a more subtle red line around the lens. Generally these lenses are made with high quality glass elements, quiet and fast "USM" autofocus motors, etc.

Mirror Lockup -A feature of some cameras that lets you flip the mirror up seperately from taking the photo to reduce camera shake that sometimes results from it flipping up automatically right before a photo is taken. This is used for studio and macro photography when sharpness is important and slow shutter speeds are used. Usually when you turn it on you'd use a remote to press the shutter button once to flip the mirror up, then wait for the vibrations to stop, and then press the shutter button once more to actually take the picture.

Motion Blur -Blurring in a photo due to a slow shutter speed combined with something in motion in the shot. Only the thing in motion is blurred. Sometimes this is good, it shows movement. But if it's not what you want, it can only be remedied by getting faster shutter speeds by lowering the aperture number or raising the ISO. If that doesn't work, you can try making the best of it by attempting a panned shot.

ND Filter -See "Neutral Density Filter".

Neutral Density Filter -Like sunglasses for your camera, this filter that darkens a photo without adding any color tint. They are usually rated by the number of "stops" of light that they remove from a photo. The purpose of these filters is to allow slower shutter speeds than you could otherwise get in bright light. One use might be to use a slow shutter speed to blur the water in a waterfall.

Noise -The graininess that appears in some photos when they are taken, usually in low light with high ISO's. It can be reduced with software although I've yet to find an effective free program to do this. But avoiding noise by using the lowest ISO possible is your best bet for a high quality image.

Normal Lens -A lens that gives a field of view that's about equal with what your eyes see. For film cameras and full-frame digital cameras they are 50mm. For cropped sensor digital cameras it's more like 30mm.

Off-Camera Flash -An external flash unit. These flashes are usually much more powerful and more flexible than the ones built into your camera -they can reach farther and can be aimed so that the light can bounced off a ceiling or wall to make it less direct and therefore less harsh and more natural looking.

On-Camera Flash -The flash that is built into your camera. It's usually not all that powerful and can give an artifical and harsh look to your photos, but it's good in a pinch.

Over-exposed -When an image is described as "over-exposed", that means it came out too light. This usually also means that the details in the lightest parts of the image were lost. Sometimes this happens because your subject is much lighter than the background or the overall scene is too dark. Exposure compensation is what you need to get around this.

Panned Shot -A technique where you use a shutter speed that would normally be too slow to stop the action of a moving object, but then you track the moving object with the camera as you take the photo so that the moving subject looks frozen and everything around it is blurred horizontally instead. This is a great technique if you can master it. You see it a lot in car magazines because it makes the car look like it's going really fast.

Photoshop -The most popular image editing software out there. Make no mistake about it, though, this is professional-level software. It's pricey and not user friendly at all. Because many people buy it and never use even half of it's functionality, I highly recommend people new to advanced image editing try Gimp. It has most of Photoshop's functionality, but it's free!

.png File -A file type that compresses the data so it takes up less room, but is non-lossy so that it doesn't loose data each time you save it like .jpeg files do.

Point And Shoot Camera -This describes a camera that does not have interchangeable lenses, doesn't give you the exact view through the viewfinder (or LCD) of the scene that will be recorded, and is designed to be used with auto modes rather than manual modes (although they may include manual modes as well). These are the cameras most people have and carry with them on vacations, etc. Some are pocket-sized, others are larger and more SLR-like. You can get good results with no knowledge of photography whatsoever with many of these cameras, but if you learn a bit about how they work, you can get some spectacular results with them as well. Eventually, though, people who are serious about photography will usually move up to an SLR for more control and predictability.

Post-Processing -Changing a photo in software after it's been taken.

PS -PS is often used as an abbreviation for Photoshop.

RAW -A setting on a digital camera that captures as much data as possible, which allows you more flexibility in changing the image's exposure, brightness, contrast, saturation, curves, levels, etc. It does, however, mean that you have to convert it to jpeg (or .png) before you can upload it to the web. And, the fact that it records more data does mean that each photo will take up more space on your memory card as well as on your computer afterwards. In general, the file size will be about the same number of megabytes that your camera has megapixels.

Rule Of Thirds -More of a suggestion than a rule, the idea is that if you imagine a tic-tac-toe board drawn across the image in your viewfinder (to divide the frame into thirds vertically and horizontally), putting your subject on one of the 4 places where those lines cross will result in a more interesting photo than if you would put it in the middle of the frame, which is often the most natural thing for us to do. This also applies to horizons -putting them at the top or bottom third of the photo is many times preferred to putting it right in the middle of the frame, which again is more natural.

Sensor Dust -On DSLR's, the sensor is exposed to air circulation whenever you change lenses. With air comes dust. If dust settles on your sensor, you get dark spots that are visible in the lighter parts of your photos (like in the sky). You can clone them out with software, but eventually you'll want to clean the sensor off. You must be careful when you clean it though, mistakes can be expensive! The best way to avoid sensor dust is to change lenses quickly and try to do it in as dust-free of an environment as possible.

Sepia -Sepia photos are two-toned just like black and whites, but instead of black the photo is displayed in a brownish hue, reproducing the look of antique photos.

Shutter (Release) Button -The button you press on a camera to take a picture.

SLR -A "Single Lens Reflex" camera. This describes a film OR digital camera with inter-changeable lenses that allows you to use full manual mode in order to control ASA/ISO, aperture, shutter speed, focus, and exposure and allows you to see, through the viewfinder, EXACTLY what your camera will record.

Shutter Speed -The amount of time the shutter stays open when you take a picture. Anything that moves while the shutter is open will be blurred, so slow shutter speeds usually require a still subject and a tripod. Fast shutter speeds will "freeze" moving people or objects without having them blurred. It's also worth noting that the longer the shutter stays open, the more light you get. So, that's why your camera may take blurry pictures indoors or at night.

Telephoto Lens -A lens that gives you a more close-up view than you usually see with your eyes. These lenses are often used for wildlife photography.

TIFF -A file type that is non-lossy, but also uncompressed. This means that you can save it as many times as you want without loosing any data, but it'll take up a lot of room on your hard drive. .png files are often preferred since they are just as safe, but smaller.

Under-Exposed -A photo is described as under-exposed if it comes out too dark. Usually this means that detail was lost in the dark areas of the photo (ie: shadows). This may happen when the overall scene is very light (ie snow scenes or beach scenes) or when your subject is dramatically darker than the background. Exposure compensation is how you fix this.

Wide Angle Lens -A lens that gives a greater field of view than you usually see with your eyes. These lenses are most often used for landscape/scenery shots.

...more to come! (If you have a term you don't understand or remember one that gave you trouble when you first started learning about this stuff, feel free to leave it in a comment or on the mailing list and I'll add it here ASAP!)