30 Terms Every Photographer Should Know

30 Terms Every Photographer Should Know

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. 

Aspect Ratio

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.


An image with smooth bokeh.

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.

Chromatic Aberration

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. 

Crop Sensor 

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

A deep depth of field used to render the entire image in focus.

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.

Dynamic Range

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

Exposure compensation refers to the photographer telling the camera to adjust its automatically calculated exposure for technical or creative reasons. 

Focal Length

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. 

Focus Distance

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. 

Full Frame

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.

Long Exposure

A long exposure used to gather more light and to create the blur of the car headlights.

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.

Manual Mode

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.

Prime Lens

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

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

A fast shutter speed used to freeze motion.

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.

White Balance

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.

Zoom Lens

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.

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Jim Bolen's picture

How about perspective correction, as in, the main image vertical's need to be fixed.

Matt Williams's picture

That's a personal preference and imo, many images look more natural without correction. Our eyes don't correct verticals - they lean and converge as they do in photos.

It depends on the photo, though - I think the main image is fine without correction given its perspective.

Not so subjective with some things (architecture outside rare cases / real estate), but otherwise agree.

Matt Williams's picture

No, I agree - I meant subjective for that photo. For architectural photography and real estate, I agree - perspective correction is almost always desired.

Gil Gamesh's picture

So oft' the dominion of the beginner / amateur, get everything into the frame, regardless of it's structural integrity. Don't be afraid to crop into what's important, or correct for perspective, please.

John Adams's picture

What you mean is perspective distortion.

I have always had an issue with the naming convention of soft/hard light. Light is just light and has no soft/hard qualities. Soft/Hard shadow is what gives definition to light. I see many beginner photographers struggle because they believe it has to do with the light and not the shadow or diffuser that creates shadow. Even a large light source such as an 6ft octobox still has a small light source. But the soft shadows are created by the defusing of the light, not the light source itself.

I know the writer has no control over the naming convention. It's just an observation.

Matt Williams's picture

It really refers to tonality: hard tonality and smooth (soft) tonality. Can be high contrast or low contrast, low key or high key, as well.

I don't really get the point of continuing to add the term prime after a fixed focal length. Saying you are using a 20mm, 28mm, 50mm, etc. gets the message across without any need to add prime every time. Adding the word prime likely adds unnecessary confusion for non-photographers.

Then we also don't need to add the term 'zoom' to a 24-70 or 200-600 lens either as it's obviously a zoom lens.

....you say zoom long enough, it sounds weird.

I don't see any reason to add zoom either. I would imagine if you did a poll that most non-photographers thing zoom means the same thing as telephoto which is also confusing.

To make it even worse, there used to be "zoom" lenses, and "vari-focal" lenses (though I think most have gone by the wayside). The difference being that a true zoom would supposedly hold focus throughout it's range while a vari-focal would need to be re-focused with each focal length change.

Zoom couldn't be completely relied upon to hold precise focus throughout the range . . . thus the old rule of "focus at maximumum length, then zoom out".

Today's glass is better and autofocus nullifies that problem considerably.

Gregory Mills's picture

As a photography teacher I can tell you it absolutely REMOVES confusion with my beginning students when I use both the focal lengths and the numbers. Until it becomes second nature to you, we who have done photography for a while forget how confusing all these numbers can be and students have to literally stop their train of thought and think about what each one means. I have to speak very slowly when I talk about lenses so new students can keep up. To put it another way, I drive an F150. Many people know that means I drive a Ford and that goes without saying but some still need me to say I drive a Ford F150 to know exactly what I drive.

John Adams's picture

Why should we care if non-photographers get confused? You have absolutely no logic in your thinking.

Why should we automatically add words that don't add any additional meaning? Your inability to understand logic doesn't negate the logic.

John Adams's picture

You have the thinking capabilities of a donut.

Matt Williams's picture

A small detail: 3x2 and 4x6 are the same ratio. And, if it were me, I'd change 8x10 to 4x5 (since they're the same) and add in 4x3 since it's easily the most common behind 3x2.

Just a minor suggestion.

Alex Cooke's picture

Ugh, thanks hahaha. Would you believe I have a master's in math?

Matt Williams's picture

yup! I majored in chemistry (so lots of math there) and I regularly have similar "oh duh" moments.

I once overheard a guy (who was pretty hard to not hear) tell his girlfriend or wife that the two most important things are f/stop and aperture. 🤣

Gregory Mills's picture

I guess he figured being 50% right X 2 makes = 100% correct?

I know all of these but disagree that every photographer needs to know them all.

John Adams's picture

If you wanna be a Mickey Mouse photographer then sure one does not need to know all technical terms.

I'm confused (again and again). What is a Mickey Mouse photographer? Is the alternative, to be a Goofy photographer? Is that what you are? ;-)

John Adams's picture

Lame comeback, try again. Downvotes for a reason ;)

I'm not trying to be clever, just friendly. How would you reply to a rude comment, without being rude?

Timothy Gasper's picture

Good enough....I guess. I would go on to define the acronym ISO....International Standards Organization which will reference back to film days of which it Replaced ASA...American Standards Association. When I was learning, and later taught, this acronym was not only stated, but defined in its entirety. This was at a time when full understanding of how photography (cameras and film) was required knowledge in order to understand the properties and qualities of light. Can't speak as to how it is taught these days, but.....

Matt Williams's picture

I don't want to bring up this debate or anything again, but ISO is not an acronym, and the name is International Organization for Standardization.

Timothy Gasper's picture

I do understand but when ISO replaced ASA BEFORE the digital age...that is exactly what it stood for. In 1974 ASA and DIN were replaced by ISO (IOS). I remember this specifically because it was part of a test.

Jakub Balut's picture

Yep, ISO took over in seventies and it still holds strong:

"Current system: ISO
The ASA and DIN film speed standards have been combined into the ISO standards since 1974.

The current International Standard for measuring the speed of colour negative film is ISO 5800:2001[17] (first published in 1979, revised in November 1987) from the International Organization for Standardization (ISO). Related standards ISO 6:1993[15] (first published in 1974) and ISO 2240:2003[16] (first published in July 1982, revised in September 1994 and corrected in October 2003) define scales for speeds of black-and-white negative film and colour reversal film, respectively.

The determination of ISO speeds with digital still-cameras is described in ISO 12232:2019 (first published in August 1998, revised in April 2006, corrected in October 2006 and again revised in February 2019).[36][37]

The ISO system defines both an arithmetic and a logarithmic scale.[38] The arithmetic ISO scale corresponds to the arithmetic ASA system, where a doubling of film sensitivity is represented by a doubling of the numerical film speed value. In the logarithmic ISO scale, which corresponds to the DIN scale, adding 3° to the numerical value constitutes a doubling of sensitivity. For example, a film rated ISO 200/24° is twice as sensitive as one rated ISO 100/21°.[38]

Commonly, the logarithmic speed is omitted; for example, "ISO 100" denotes "ISO 100/21°",[39] while logarithmic ISO speeds are written as "ISO 21°" as per the standard."

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