Photography is full of hundreds of terms. Here are 30 of the most important to know.
To put it simply, aperture is the size of the opening of your lens that lets light through: make it wider, and you let more light through. Make it narrower, and you let less light through. A wide aperture (such as f/1.4) lets more light through, allowing you to use a faster shutter speed or lower ISO, but the tradeoff is less depth of field (how much of the image is in focus). A narrower aperture (such as f/8) lets less light through, requiring a slower shutter speed or higher ISO, but results in more of your image being in focus.
This refers to the ratio of width to height, normally in reference to the crop of an image or a camera sensor's dimensions. Common camera sensor aspect ratios are 4x3 and 3x2. Common image aspect ratios are 1x1, 4x3, 4x6, 5x7, and 4x5.
This refers to the subjective quality of the blur of out-of-focus elements in an image. Most photographers look for smooth bokeh that isn't "busy" so as to not distract from the rest of the image. They also prefer that light sources be rendered in smooth, uniform balls, as opposed to polygons or irregularly filled shapes.
A common issue in which a lens does not focus all frequencies of light to the same point. It frequently shows up as purple or green fringes around high-contrast edges at wide apertures.
A crop sensor is one that is smaller than a full frame sensor. Crop sensors frequently mean smaller and cheaper cameras. In addition, they can make the effective focal length of a lens longer, but the tradeoff is worse low-light performance and dynamic range compared to a similar full frame sensor.
Depth of Field
This refers to how much of an image is acceptably in focus, measured in physical units of distance. Photographers will often use a shallow depth of field to isolate a subject and wide depth of field when they want everything in an image to be reasonably in focus. A wide aperture (f/1.4, f/2, etc.) produces a shallow depth of field, while a narrow aperture (f/11, f/16, etc.) produces a wide depth of field.
DSLR stands for "digital single lens reflex." This is a digital camera in which light passes through the lens, through a series of mirrors, and up to the viewfinder and is the most common type of digital camera in use by hobbyists and professionals. They are desirable because they show the image composition "as the lens sees it," avoiding issues with parallax error.
The ratio between the largest and smallest amounts of light a sensor can simultaneously capture. In other words, dynamic range measures how wide a variation in light across the image a camera can record. Cameras with higher dynamic range are more desirable.
How light or dark an image is. Exposure is determined by a combination of shutter speed, aperture, and ISO.
Exposure compensation refers to the photographer telling the camera to adjust its automatically calculated exposure for technical or creative reasons.
How strongly a lens converges rays of light. Focal length determines how "zoomed in" an image is. Shorter focal lengths (wide angle lenses — 14mm, 24mm, 35mm, etc.) produce wider images that can capture more of a scene. Longer focal lengths (telephoto lenses — 135mm, 200mm, etc.) produce narrower images that show less of a scene but capture a more zoomed-in image.
The distance (along the axis parallel to the lens) in an image at which light rays from a point converge as much as possible. In other words, the focus distance corresponds to the point in the image where elements are rendered at maximum sharpness.
The ratio of a lens' focal length to the diameter of its entrance pupil. The f-stop gives a quantitative correspondence to aperture. Smaller f-stops, like f/1.4 or f/2, indicate a wider aperture, while larger f-stops, like f/11 or f/16, indicate a narrower aperture.
A full frame camera has a sensor that is 36x24mm and is the standard to which other sensor sizes are compared and focal lengths are specified. Full frame sensors generally offer better low-light performance and dynamic range than a comparable camera with a smaller sensor.
Hard and Soft Light
Hard light is produced by sources that are relatively small (small in physical size and/or far from the subject) and produces harsh, defined shadows and quick transitions between light and shadow. Midday sun is a good example of hard light. Soft light produces slower transitions between light and shadow and a more diffuse look and is considered more flattering in a lot of cases.
A graph showing the distribution of tonality in an image, useful for determining proper exposure.
ISO, for all intents and purposes, is how sensitive the camera is to light. Low ISOs (100, 200, etc.) indicate low sensitivity and thus require more light to produce a proper exposure. High ISOs (3,200, 6,400, etc.) indicate higher sensitivity and require less light. The tradeoff is that higher ISOs produce more noise (making an image look grainy), less detail, and reduced dynamic range. ISO is used in tandem with shutter speed and aperture to create an exposure.
An image that uses a shutter speed with an intentionally lengthy duration, allowing the photographer to gather more light or create artistic effects by blurring objects in motion.
This refers to the camera mode in which the three exposure parameters (shutter speed, aperture, and ISO) are totally controlled by the photographer with no automatic input from the camera. Many photographers use this mode in a variety of situations for increased technical and creative control.
Metering refers to how the camera measures the amount of light in a scene to help it calculate the proper exposure. Most cameras have a range of metering options for different situations.
A mirrorless camera uses a tiny monitor in place of an optical viewfinder. This has certain advantages, like better visibility in low-light situations. The industry is gradually transitioning away from DSLRs to mirrorless cameras.
Noise normally refers to random fluctuations in image brightness or color information on the pixel level and is generally undesirable in images. Noise increases as ISO increases.
A lens with a single focal length. Prime lenses often feature simpler designs, resulting in smaller weights and sizes, and often, lower prices. They frequently have wider apertures and are often sharper than zoom lenses.
A raw file is the data taken from the sensor without any sort of image processing applied (as opposed to a JPEG produced by the camera). Though bigger in file size, photographers prefer raw files because they allow for more creative range in post-processing and higher image quality before exporting the final image in a file format like JPEG.
The total amount of pixels in an image or on an image sensor. Higher resolution can render more detail in a photo. Resolution is typically measured in megapixels (millions of pixels).
Rule of Thirds
A common compositional tool that states that one should divide the image frame into equal vertical and horizontal thirds, then place points of interest at the intersections of the dividing lines.
Sync speed refers to the fastest shutter speed at which a camera can use a flash (normally around 1/200 s) — a consequence of the mechanism of a focal plane shutter. Various flash manufacturers have created special modes that can push past this limit with various tradeoffs.
Shutter speed refers to how long the camera's shutter is open for. Longer shutter speeds (1/10 s, 1 s, 3 s, etc.) allow more light in but will result in more blurring of anything that is moving during the exposure. Shorter shutter speeds (1/200 s, 1/1,000 s, etc.) let less light in but do a better job of freezing motion.
The setting that your camera uses to assume the color temperature of light in an image. This affects the overall color of your photos. Shooting in raw allows you to adjust the white balance in post, usually without a penalty in image quality.
A lens with variable focal lengths. Zoom lenses have more complex designs, resulting in larger weights and sizes, and often, higher prices. They are often not as sharp as prime lenses (though modern zooms are often impressively sharp) and have smaller apertures.