At first glance there seems to be an endless array of jargon and terms used to describe today’s DSLR cameras and their functions. In fact, even the term DSLR is used to describe today’s cameras. So, why don’t we start with this and move down the list.
DSLR: This acronym stands for “Digital Single Lens Reflex”. Simply put, this is a camera that uses a mirror and prism system allowing the photographer to see through a viewfinder the exact image that will be captured via the lens. This is achieved by light coming through the aperture in the lens and being redirected via the mirrors inside of the camera.
Autofocus: Most, if not all, of today’s DSLR cameras come with autofocus functions. This simply means that when you point the camera at your subject and press the shutter button halfway that the camera will engage the AF function and acquire focus. By pressing the shutter all the way down the camera then takes a crisp, in focus shot of your subject. Auto focus is used almost exclusively in bird and nature photography to ensure quick and accurate focus of an often non static subject. The autofocus features on your camera will work better in good lighting situations with higher contrast scenes. It will also perform differently depending on the actual camera body and lens combination that you are shooting with.
Buffer: The term buffer refers to the temporary storage space were the image information is written to before being processed and moved to the memory card. The time it takes will be dependent on the size of your buffer which is usually measured in megabytes of RAM or “random access memory”.
Burst Mode: Burst mode is a term that refers to your cameras ability to make many images in a short succession. These shots are stored in the buffer before being written to the memory card. If you have a large buffer capacity your camera will write the image data faster allowing for quicker shooting or frames per second.
Compact Flash: Even though this may sound like a smaller flash unit, this term describes a type of memory card used to store image data. All compact flash cards have a wide variance of storage capacity generally ranging from 1 to 64 GB. In nature photography I like to use 16 and 32 GB (Gig) cards as they have lots of storage and allow me to have my images spread out more instead of having them all in one 64 GB (Gig) basket so to speak.
Compression: In SLR terms compression refers to the way in which files are downsized for more storage capability as well as quick access and use. Generally there are two types of compression, Lossless and Lossy. A RAW image file is a “Lossless” file where no data is thrown away during compression. A” Lossy” file example is a JPEG file where some of the image data is thrown away when going through the compression process.
Depth of Field of “DOF”: The area in an image that is in sharp focus behind and in front of and even sometimes, on your subject. DOF is affected by the F-stop or Aperture, the distance from your subject as well as the focal length of the lens you are using.
EXIF: This term is the short form for “exchangeable image file”. It is meta data that your camera embeds on any given image that will include information such as make and model of the camera, date and time, shooting data like shutter speed, F-stop and ISO.
Exposure: This simply means how much light is used to create an image by allowing a certain amount of light onto the sensor. It is controlled by the shutter speed, F-stop/Aperture and the ISO. This is commonly referred to as the “Exposure Triangle”.
Exposure Triangle: The exposure triangle is made of the 3 major things that affect our exposure. Shutter speed, F-stop or Aperture and ISO all combine to make the exposure triangle.
Exposure Value or EV: This simply means the calculated exposure value by combining the shutter speed, F-stop and ISO.
F-stop: This is a numeric value that we use to tell us the relative size of the aperture opening in the lens. The lower the F-stop value, the larger the aperture opening. The larger the F-stop numeric value, the smaller the aperture opening.
Tip: The term “opening up” refers to stopping down to the lowest value F-stop to increase the aperture opening to its largest diameter therefore letting more light onto the sensor.
Histogram: A histogram is a basic bar chart that shows us 255 different tonal values from 0 to 255, 0 being pure black and 255 being pure white. The vertical lines represent the number of pixels in an image that coincide with that particular tonal range value. The middle of the histogram represents the neutral tones or “neutral grey” areas of the image while all the information to the left is darker than neutral grey and all of the information to the right is brighter than neutral grey. The histogram is a useful tool that allows the photographer to see how much room there is to “push the whites” without clipping or overexposing the highest contrast or brightest area of an image.
Image Stabilization: A feature that compensates for camera shake or movement to help eliminate not sharp images. It is very useful for low light situations.
ISO: ISO is an acronym left over from the film days that stood for International Standards Organization. The term ISO was used to describe the speed of a film or its sensitivity to light. The faster the film speed the more light the film emulsions could absorb. So you had film speeds such as 400, 800, 1000 and 1600. The term ISO has stuck around and is now used to set how sensitive our digital sensor is to light. The faster the ISO setting in your DSLR, the more sensitive the pixels are to light. Higher ISO’s are used as a last resort in nature photography when you can’t get a fast enough shutter speed with the available light that you have and increasing the ISO setting will give you more effective stops of light and the faster shutter speed you desire... I say this because higher ISO’s introduce noise into our digital files, an unwelcome sight for most nature images.
JPEG: JPEG is an acronym used to describe a type of digital image file format. It is the most common file used today because of its relatively small size and because it is the most widely accepted form of digital image sharing on the World Wide Web.
Live View: This allows a photographer to compose an image using the LCD screen on the back of the camera.
Megapixel: The name itself invokes thoughts of “I need lots of megapixels” on the camera that I buy! One megapixel is equal to one million pixels. Megapixels are used to describe the camera’s resolution capabilities. It is the standard unit of measurement for DSLR camera resolution. The more megapixels your camera has, the more data and the larger the file size. You will get more detail and better image quality with a higher amount of megapixels.
Memory Card: A memory card is a removable solid state card that is the known standard for recording our camera’s image files. The two most common are Compact Flash and SD.
Noise: Noise is the term used to describe usually unwanted specks or squares in our digital images. It is most commonly caused by using higher ISO settings in low light situations.
Noise reduction: The term used to describe either or cameras on board noise reduction capabilities or a software program that we can use on our computer when processing our digital files.
Pixel: Pixels are tiny dots of digital information that, when combined, make our image. A digitals image resolution is measured by the amount of pixels that are combined by the height and width of the image file.
PPI: This refers to pixels per inch. The more pixels there are per inch, the higher the resolution is. This is a common reference for printing.
RAW: This is an unprocessed, uncompressed or lossless digital file format. It is a true and complete recording of what your DSLR sees when you take your image. They are larger size files that take up more storage space than a JPEG file. They also require more time to write to the memory card.
SD Card: This is a short form for secure digital cards. They are smaller and some DSLRs hold both a compact flash card slot as well as an SD card slot. They tend not to be as fast at data transfer as the larger CF cards.
Sensor: This is simply the part of your camera that turns incoming light into digital data thereby creating the image we are making.
Tonal Range: This is the term used to describe the quality of tones from pure black to pure white in a given image. This is easily viewed using the camera’s histogram.
White Balance: The term white balance refers to the true white in an image and is used as a reference point by the camera to ensure the other colors in the image are rendered naturally.
Looking for photo tips with these terms. Read all about them in David Hemmings Photo101 Book.
