If you’re new to photography or shopping around to buy a camera or lens it can be confusing decyphering all the names and acronyms that photographers use. It’s not unusual on a shoot for me to ask my assistant to pass me an 11-16 2.8 DX whilst setting a flash 2 stops up from 1/64th and add a shoot-through… for example. When I do clients often remark that I’m speaking a foreign language.
So here it is. A list of some useful terms for understanding your equipment or the photographers you’re working with if you’re new to the field. It’s not comprehensive but hopefully it is useful. If you can’t find what you need just leave a comment with the term you need explaining and I’ll add it to the list.
Body – The actual camera itself. This needs little explaining, except that a DSLR differs from an all-in-one by having interchangeable lenses.
SLR – Stands for Single Lens Reflex utilising a flip up mirror allowing you to frame your image through the viewfinder. The mirror flips down at the moment you press the shutter release to give the same exact view to your sensor.
Lens – Any means by which light enters the camera. This can be anything from a complex 22 optic telephoto to a simple hole in a flat lens cap, like a pinhole camera.
Full frame or ‘FX – An SLR body with a sensor with the same area as 35mm film, typically 24x36mm. FX cameras are usually built for professional use. They are much more expensive than crop or ‘DX’ cameras and are the holy grail to most amateur photographers due to their excellent low light performance, large viewfinders and high cost. Lenses for FX must be specifically designed to use a large enough image circle to cover the sensor.
Crop or ‘DX‘ – An SLR body with a smaller or ‘cropped’ sensor equivalent to APS-C sized film at 16x24mm. Most consumer cameras use this smaller size as it is cheaper an easier to produce. It also allows the body to be smaller and more portable but at the cost of poorer low light performance and smaller viewfinders. Lenses for DX are often much cheaper than for larger sensors. Because of the small sensor less glass can be used resulting in light, portable lenses. DX lenses project an image circle too small for full frame cameras so either don’t work or suffer from heavy vignetting.
Crop factor – This describes the relationship between a 35mm sensor and the sensor in a DX camera and the resulting equivalent focus length. When a 20mm lens is mounted on a Nikon DX body it gives the same field of view as 30mm on a full frame, giving a 1.5 crop factor. 20mm x 1.5 = 30mm. Canon DX bodies have a 1.6 crop factor so would give a 32mm field of view. 20mm x 1.6 = 32mm.
Field of view – The arc describing how wide the view from a lens is in degrees. This is usually based on the focal length of a lens mounted on a full frame 35mm sensor. For example a 20mm lens has a field of view of 92.4 degrees, 50mm lens has a field of view of 46.4 degrees. a 105mm lens has a field of view of 23.1 degrees and so on. To put this in perspective, if you close one eye your field of view is approximately 95 degrees across. You can test this by holding your arms out at right angles and trying to see both of your hands with one eye closed.
Depth of field or ‘DOF’ – You’ll hear this a lot. Photographers love to talk about DOF. It’s the reason we’re happy to spend hundreds to get the f1.4 lens rather than the f1.8. It describes how much (or how little) we can have in focus in our image. A large depth of field allows you to capture both the fore and background of an image in focus. A shallow depth of field allows you to isolate your subject in focus and throw your fore and backgrounds out of focus making them blurry. You can treat this as if a large depth of field (high f number) puts everything in focus. In fact, accurate focus is always a wafer thin 2D plane somewhere in your image. Everywhere else is either in acceptable focus or not.
The exposure triangle
No this is not an area of the Pacific where cameras go missing, but a name sometimes given to the three things you can change to vary an exposure.
Shutter speed – This is fairly obvious, it’s the length of time the shutter is open for and your sensor is exposed to the image. Measured in increments of 1 second or in whole seconds.Typical speeds for freezing action might be as follows: Still subjects 1/60th of a second. People walking 1/125s. Sports 1/1000s.
Aperture – This is the element inside the lens, usually a 6 to 9 blade iris that opens and closes to allow more or less light through the lens. Aperture is typically measured on the F-stop scale and can be a little confusing at first. A large aperture lets in a lot of light and has a low f number such as f2.8. A small aperture lets in less light and has a high f number such as f22. Aperture is not only responsible for light input but also for depth of field, bokeh and chromatic aberration. Most lenses/cameras can change the aperture in 1/3, 1/2 or full f stops. The full stop scale looks like this: 1.4, 1.8, 2.8, 4, 5.6, 8, 11, 16, 22. These days a lens with an aperture of f2.8 or larger (smaller number) is considered ‘fast’.
ISO – The sensitivity of your sensor to light, or more accurately the gain on the amplification of your sensor. Based on the old scale of film sensitivity. Low ISO settings yield the cleanest most detailed results. High ISO settings are used for darker conditions or to increase the shutter speed needed for capturing action. This performance is traded for detail as the higher ISO brings ‘noise’ into the image. Amateurs worry about noise way too much. It’s almost always better to get a sharp noisy image than a clean blurry one. ISO performance depends on a number of factors. Technology is one for sure but photosite, or pixel size is the main contributor. Full frame cameras with relatively low megapixels offer very clean high ISO images due to their large pixels collecting a lot of light.
Lens types (when mounted on FX)
Ultra wide – Lenses in the region of 12-18mm. These lenses see a very wide angle of view and include fish eye optics. At the very wide end they are capable of a huge field of view. You have to be careful using lenses this wide as they can distort images considerably. Objects closest to the lens will appear huge in the frame where as everything else can look very small. If you’re craving a super wide try to borrow or rent one first to see if it’s really of use.
Wide – Lenses from 18-35mm Standard wide lenses. Great for street and architectural photography as well as groups with less distortion than ultrawides. Even fast aperture wide lenses tend to have a very large depth of field.
Normal – 35-85mm is considered a normal lens. A 50mm lens gives an equivalent view to the human eye in that the relationship between objects stays the same as when we look at them. 50mm 1.8 prime lenses are very popular as walkaround lenses for this reason. Snaps from a ‘nifty fifty’ just look right.
Short telephoto – 85-135mm lenses are the most common for portrait photography because the focal length coupled with a fast aperture gives a very shallow depth of field for flattering shots without distracting backgrounds.
Long telephoto – 135mm+ Used primarily for sports and nature photography but found in every photographers bag. Longer lenses are often slower (f5.6+) in consumer models so require a lot more light than wide lenses. They are also harder to hold still for longer shutter speeds so often have vibration reduction to help.
Macro – Designed to focus close up on small objects. A true macro lens has a 1:1 reproduction ratio meaning it can project objects at their actual size onto the image sensor.
Vibration reduction – VR (Nikon), IS (Canon), OS (Sigma), VC (Tamron). This technology allows the use of slower than normal shutter speed to get sharp shots by stabalising the image as it passes through the lens. Most work by sensing the movement of the image within the lens and correcting it with a floating lens element near the sensor. VR will not fix subject blur, only motion blur.
AF – Auto focus. Lenses will communicate with the camera and acquire focus when the shutter button is pressed.
IF – Internal focus lenses can go through their entire focus range without changing the length of the lens. This is better in all sorts of ways but primarily it means that the lens won’t suck air or weather in as it focuses.
AFS, USM, HSM – These are Nikon, Canon and Sigmas acronyms for fast, accurate, silent focus motors within their lenses. Usually featuring on the more expensive models these are ideal for fast moving subjects or where silent operation is important.
ED , L Series – Nikon and Canons top end glass. These include ‘Low dispersion’ elements to minimise aberrations in the image. Lenses with ED or L elements are coveted by professionals and high budget amateurs.
There is lot’s more to define but that’s it for this post. More will be added so as always, if you have a questions just ask.