30 Photography Terms Explained: What Is Aperture, Shutter Speed And ISO?

From Pixel To Phase Detection Autofocus: Know 'Em All

So many photography terms, so little time

Photography. The pursuit of human to capture a moment that they can cherish forever. Some of the most iconic images have had strong impacts on our way of thinking. But not everyone understands the complex terms that encapsulate the art of photography.

While the art is quite complex and needs days of dedicated study, knowing the terms involved will give you a head start. We’re assuming you already know what terms like lenses, selfie (d’uh), landscape and portrait mean. We’re going alphabetical on the more complex terms.

Here are the 30 most important ones.

1. Aperture (aka f-stop)

If you’ve ever seen a camera lens closely, you’d notice the blades that close when the shutter button is clicked. The opening of the blades is adjustable and this is what the term Aperture refers to.

The term is also known as f-stop, the lower is the number for an f-stop, the larger is the opening of the lens blades. A larger opening helps in low light situation, whereas a smaller one helps with blurring the background and keeping only your subject in focus.


The above illustration shows exactly how the lens blade work when going from one f-stop value to another. Check out the background in correlation to the way the lens opens and closes to know how it works in real world shooting with a camera.

2. Aspect ratio

When we’re working on a monitor, looking at images, there are only 2 dimensions. The width and the height. The ratio between the two is the aspect ratio. This is the simplest way to understand the concept and take photos accordingly.

Difference in Aspect Ratios

If you are looking to take photos that need more width than height, it’s better to go for the 16:9 aspect ratio. But if you want the height to be captured too, then a 4:3 aspect ratio is better suited.

3. Autofocus

While shooting, the camera should focus on the subject and capture the moment before it moves. But if the subject if your pet dog or a moving vehicle, you might not always get the photo you wanted. This is where Autofocus (AF) comes into the picture.

The Autofocus (AF) feature enables the camera to take over the focusing job from the photographer while he can concentrate on the framing.

What’s framing? We’ll cover that later in the Rule of Thirds below. There are different types of Autofocus modes in modern cameras, with the most popular being AF Servo Mode where the subject remains in focus even if its in constant motion.

4. Bokeh

This term gets tossed around more than United’s passengers in their overbooked flights. All kidding aside, the term which traces its origin to Japanese origins, refers to the quality of out-of-focus part in any picture. The smoother and more pleasing is the out-of-focus part, the better the image will look.

Photographers tend to put only their subjects in focus while leaving everything else blurred. This is what bokeh refers to, with smartphone cameras trying to achieve this by digital manipulations. The technical term for Bokeh is ‘Shallow Depth of Field’.

5. Burst mode

When a fast moving action sequence needs to be captured frame-by-frame, it is the shutter that needs to move quickly. It can only do that if the Burst mode feature is available on the camera. This mode allows the photographer to capture shots a mere fraction of seconds apart.

Some DSLRs don’t specify this mode separately as the desired images can be achieved by lowering the shutter speed to something like 1/500th of a second. If you hold down the shutter button with this set speed, you can easily capture a set of 7-10 photos (depending on camera performance) in rapid succession.

6. CMOS sensor

The sensor of any camera is where the image is captured. The physical size of the sensor determines how well-defined the final image will be. In most DSLRs, the technology used to create these sensors is CMOS technology. Hence the sensors are called CMOS sensors.

7. Crop factor

Photography has evolved from film to digital and as a reminder of that past remains a term which tries to compare the size of an image to its full-frame film counterpart. The older film cameras used 35mm film (1 x 1.5 inches) but digital cameras have smaller sensors producing a ‘crop factor’ of 1.x times, compared to the full frame 35mm film cameras of yore.

Digital camera sensor format

Modern digital DSLR cameras are thus categorised as being ‘full frame’ cameras and APS-C cameras, where the C indicates the crop factor of a smaller sensor.

8. DSLR camera

A DSLR camera is the one loaded with tons of advanced features, has interchangeable lens mount and is equipped with a fairly large image sensor. While you can start off with a DSLR camera, you should also ask yourself these important questions before you make the plunge.

9. Depth of field

Even though we see images in 2 dimensions, we do get some idea about the depth. Like we explained in our Aperture section, the background can be kept completely out of focus. But the level of depth which is out of background can vary. This is what depth of field refers to.

10. EXIF

Every image you take, no matter from which device, has quite a lot of details embedded in it. We’re not talking about just the size and resolution, but which device was used to capture it, the ISO at which the image was taken, the aperture and even the place where it was taken can be found. All of this is stored in the EXIF data for images.

11. Exposure and exposure compensation

The amount of light on your subject determines whether you will be able to take the perfect shot. If the light is insufficient or way too bright, then you have to play with the Exposure Value (EV) of the camera. Giving it a positive value (+1EV, +4EV etc.) can increase the exposure whereas a negative value will decrease it.

Varying exposure value with its intended effect | Photo courtesy: Stephen Elms

Adjusting the aperture (f-stop), shutter speed and ISO will have an impact on the exposure of your picture. But having a greater amount of control with Exposure Value will result in the perfect shot no matter how bad the lighting condition is.

12. Focal length

Focal length is a little complicated to describe but the easiest way to explain it, is to say that it is the distance between the sensor and the subject, expressed in millimetres (mm). When talking about lenses, the focal length represents the physical length as well as the field of view. These, in turn, will also affect the angle of view. The image below explains this clearly.

Focal length

13. HDR

HDR stands for High Dynamic Range and is a feature also found in smartphone cameras, these days. This term describes the ability of a camera to capture as wide a range of colour as possible with as accurate an amount of light falling on it.

You’ll see the effects of HDR mode clearly in shots where some areas are flushed with light while other areas are in the shadow.

14. Hot shoe

A hot shoe is usually found in DSLR cameras at the top panel, where other accessories like an external flash light can be attached. It’s more like a port in modern day laptops and doesn’t have anything to do with photography techniques and the ilk.

15. ISO

The term ISO refers to the sensitivity of light you want your photo to be taken at. A higher ISO number will try to bump up the sensitivity more and brighten up a normally dark image. The down side is that a higher ISO usually introduces a little bit of unwanted noise.

16. Lenses

There are several types of lenses that can be used on a DSLR. Some have fixed focal lengths with impressive image quality whereas some have zoom functionality to capture objects afar. Some of the more popular lenses are –

  • Wide angle lens: If you’re object is really close, a regular lens will not be able to capture the subject completely. For such situations, photographers choose a wide angle lens.
  • Telephoto lens: The term telephoto is a technical one for ‘zoom’ lens. Any lens that can focus at subjects which are far away are telephoto lenses. They normally begin at a 135mm focal length and can go all the way to 1000mm.
  • Prime lens: These types of lenses have a fixed focal length. There is no fiddling around with the lens to adjust the focal length and as a photographer you will have to move around more, to capture images with a prime lens.

17. Long exposure

Ever seen a picture in perfect focus but still containing a trail of lights? That’s the magic of long exposure at work. If you have really steady hands (or use a tripod like the pros), you can adjust the shutter speed of the camera to be around 1 second (or longer) to achieve similar results.

Can you see the cars, or only their trailing lights?

18. Phase detection autofocus

This term refers to the ability of a camera’s sensor to ‘split’ the image in two and then merge them together (i.e. bring them in phase). The main advantage here is the speed of focus.

19. Noise

If you’ve ever noticed a grainy effect on any photo that you’ve clicked then you already know what we’re talking about. Noise refers to the introduction of distortion while capturing a photograph.

Varying level of noise for the same location in the same lighting condition

There are several reasons why noise gets introduced to a picture, the primary being high ISO value in a low lit condition.

20. Optical Image Stabilisation (OIS)

There are several moving parts inside a camera and even in the camera of your smartphone. But even the slightest movement will result in a ‘blur’ image, which isn’t ideal. To counter the shaky hands, brands introduced the concept of Optical Image Stabilisation (OIS) where the camera lens itself can move enough to counteract shakiness.

Since this requires more space in the body of a smartphone, some brands prefer going the digital router – EIS. With Electronic Image Stabilisation (EIS), the camera lens need not move – it’s done via software wizardry.

21. Optical zoom

Capturing an object from afar is always challenging but modern lenses can really zoom in. There are two kinds of zoom here too, optical and digital. With optical zoom, it is the lens element that are programmed to increase their focal range and move inside the body. Whereas in digital zoom, no lens movement is needed as digital cropping tries to achieve similar results as optical zoom.

Needless to say that OIS tends to give better results compared to EIS. However, with the way technology is moving, EIS 3.0 is actually pretty impressive when compared to OIS.

22. Panorama

Normally, we take images which are rectangular in shape. Only so much of the surrounding can fit into the frame. If you need to fit more in one direction (either horizontal or vertical), you need to switch to Panorama – which describes a sweeping series of images and stitches them together.

23. Pixels

When we moved from the ‘film’ world into the digital world, every image got described by its size. And instead of inches and centimetres, we moved to pixels – the unit of measuring the size of images.

Number of pixels determine the size of images

Megapixels, therefore, is a collective of a thousand pixels. But a larger pixel count does not a good camera make. It only gives you an idea of the size of the image – nothing more, nothing less.

24. RAW files

The default file type for most camera images is JPEG. This is a compressed file format and does not retain as much details as a pro photographer would like (but is okay for most people). This is where the RAW format comes into play, which (as the name suggests) is the absolute 100% detail capturing mode of a camera.

The tradeoff here is that the size of each image captured in RAW is huge and the storage will be exhausted in no time.

25. Resolution

As we’ve explained earlier, the pixels are what make up an image in the digital world. The thousands of pixels arranged vertically and horizontally combined give you the resolution of the image. When you normally hear a resolution like 13 Megapixel or 16 Megapixel, it is the highest resolution you can expect from that camera.

Lowering resolution to save space (or a different aspect ratio) is always possible on cameras but increasing from max value is not.

26. Rule of thirds

This is one term that gets thrown around a lot. The rule of thirds refers to the technique of framing an image when you want to capture something. Imagine the frame you’re capturing is divided into 3 equal horizontal and vertical blocks. The lines where they intersect is where the focus point of your subject needs to be.


As with most art forms, this is only a reference to what a good picture should be like. Not a rule set in stone.

27. Shutter speed

The time taken by the shutter of the lens to open the aperture and close them is what we refer to as shutter speed.

28. Time lapse

Ever seen a video where the people appear to be moving like they used to back in Charlie Chaplin movies? That is not even a video but a series of images playing back to back to create the illusion of a video. This photography technique is referred to as a time lapse.

29. Viewfinder

The peeping hole from where we can look at what we’re shooting is the viewfinder. We have hybrid viewfinders in most DSLRs where only optics aid the photographer to view the frame but digital elements also give him an idea of various readings like the f-stop, shutter speed, ISO and even exposure.

There are completely electronic viewfinders as well, especially on Sony & Fujifilm cameras. These are called Electronic Viewfinders or EVF.

30. White balance

Finally, we come to White Balance – a term used to describe the calibration of colours. In this feature, photographers merely need to get the white colour as accurate to how it looks in real life. A white iPhone might look a bit different indoors to what it does outdoor and in different kinds of lighting.

White balance aims to adjust the colour tones to what a photograph prefers and since we can adjust it for white, the camera automagically calibrates it for other colours too.

Ready to shoot?

Knowing what the terms mean is only half the battle. Actually going out and taking some pictures is the best way to grow your knowledge about photography.

Thinker. Tinkerer. Writer. Editor. Many hats, one heart. Several roles, one goal. You get the picture. Right?


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