Basic Photography Terms

Discuss cameras, settings, composition, or anything related to photography - cactus or other subjects.
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Harriet
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Basic Photography Terms

Post by Harriet »

Here's a beginners overview of camera terms I wrote for a client. I have found that having the most basic information helps me to understand how to deal with the more complicated aspects of my camera, so I hope this can help some of you get a better handle on what's behind the point and click on your cameras.

Aperture
The aperture is the opening in the lens that allows light to pass through, carrying the image to the digital camera sensor. Changing the size of the aperture increases or decreases the amount of light entering the lens.
The different aperture sizes are indicated by a series of numbers called f/stops, F-Stops or Stops. The larger the number defining the f/stop, the smaller the opening. Therefore:
Larger f/stop settings have smaller openings and allow less light into the camera.
Smaller f/stop settings have larger openings and allow more light into the camera.
If you adjust the aperture settings you also have to adjust shutter speed. If the aperture is very small the shutter speed that may be required to compensate may be so slow that you may not be able to hold the camera steady long enough to capture an acceptable image.


Depth of Field
Depth of Field, or Depth of Sharpness, depends upon the diameter of the Aperture hole. The smaller the hole, the more of the picture distance is in acceptable focus.
This image was captured using a large aperture:
Image
This is the same image captured using a small aperture:
Image
As an example, when you have a large group of people, and everyone’s face is a different distance from the camera, it is better to have a smaller aperture (hole) so everyone’s face is more in focus.
In addition, light makes a difference in the depth of field, as the amount of light captured in your image is affected by the size of the aperture (and shutter speed). Usually brighter daylight shots have more depth, while darker nighttime shots have less depth of field since the aperture is larger (and the shutter speed is slower).


Exposure
Exposure is defined as the amount of light that enters the camera and is captured by the light-sensitive material inside the camera. It is a product of the quantity of light multiplied by time of the exposure. The quantity refers to the size of the aperture, or F-stop. The time refers to the shutter speed, or the amount of time that the shutter is open to allow light to pass into the camera.
If you double the size of the hole (or in photography terms, reducing the aperture number by 1 “stop”), you will allow twice as much light into the camera.
Similarly, if you double the amount if time that light enters the camera (or in photography terms, doubling the shutter speed, like from 1/250th to 1/125th) you will again allow twice as much light into the camera.


File Size
The file size of the picture is measured in Megabytes (MB). It is the amount of space (or memory) required to store the image. The higher the resolution, the bigger the file size.
Although affected by the choice made to determine the image size of your images, file size is NOT the same as image size.


Focal Point
A focal point is the main area (or areas) of interest in the captured image. It is the place in your image where you want the viewer to focus. Although the focal point is generally the area on which your camera will focus, it is not necessarily the same as the “focus area” of your camera.

Image Size and Image Quality
The image size is the physical dimension of the image as determined by the default settings on the camera. There are three settings for image size on a Nikon digital camera, Large, Medium, and Small. Most digital cameras have the same or similar settings.
There are also three settings for the quality of the images stored as JPG files by a Nikon digital camera: Fine, Normal and Basic. As with image size, most digital cameras have the same or similar settings.
Image quality has to do with how much each image is compressed. (Fine images are compressed less than Normal images, which in turn, are compressed less than Basic images.) When images are compressed resolution is lost.


ISO
The ISO of your camera’s sensor is a measure of how sensitive it is to light.
“Normal” ISO, for taking shots outdoors on bright sunny days is 100 (or 200 on some Nikon digital cameras). If light levels drop when using this setting, you can compensate by increasing aperture size or decreasing the shutter speed to allow more light to reach the sensor. If the new settings do not correct the problem, then a different ISO value can be chosen.
If you change the ISO setting to a higher than recommended value, your images may have a speckling effect called “digital noise”.


Picture Elements (Pixels)
A pixel is the smallest part of a digital picture. The digital image is composed of millions of these tiny squares. The squares are not noticeable unless the picture is enlarged many times.

Each camera has different settings for photo-quality digital images. The setting for photo-quality images on the camera you use may be referred to as “fine” or “large”, or may have some other designation. The actual settings for specific cameras are discussed in the documentation on the camera.
What you need to know is that, however the setting is defined in your camera’s setup, the more pixels in the picture, the sharper the picture will be.
A megapixel is one million pixels. When a camera is rated at “4.0 Megapixels” it means that its images can consist of up to 4 million tiny squares.


Resolution
Resolution is the fine detail (or lack of it) captured in the image. The greater the resolution, the better the picture quality (and the greater the file size). Image resolution refers to the number of pixels in an image. The linear measurement is defined in pixels per inch (ppi).
Resolution settings have a direct relation to the image size because of the number of pixels used to capture the image. On digital cameras the resolution settings are governed by the number of pixels that are in the captured image.


Shutter Speed
Shutter speed is the amount of time the shutter opens. This time determines how much light reaches the light sensitive material that stores the image. “Fast” shutter speeds reduce the amount of light allowed into the camera by reducing the time the shutter is open. They would typically be used in shooting situations with very bright light. “Slow” shutter speeds let in more light over a longer period of time and are used in low-light shooting situations.
Shutter speeds are indicated by numbers 1, 2, 4, 8, 15, 30, 60, 125, 250, and so on. The numbers represent the bottom number of a fraction of a second (except 1), and are equivalent to 1 second, 1/2 second, 1/4 second, 1/8 second, and so on.
The slower the shutter speed, the more likely you are to move the camera and thus capture an unacceptable image.
The shutter speed settings differ slightly from camera to camera.
The camera was set to a fast shutter speed to capture the image below.
Image

Since most of the images you will be capturing are of stationary subjects (and not running dogs), the preferred camera settings will allow the shutter speed to be controlled by the camera rather than the photographer.


Zoom
There are two kinds of zoom on digital cameras, Optical (preferred) and Digital. An optical zoom uses the entire CCD area and does the zooming with the lens. This gives you the highest resolution. A digital zoom, on the other hand, crops the CCD area and then expands that smaller image electronically by adding pixels, thereby losing detail.
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hob
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Post by hob »

great tutorial Harriet, well written, explains all the major issues well. =D>
incurable cactoholic
growing rebutia's with a mix of others.
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SnowFella
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Post by SnowFella »

:thumbup:
Spot on explanations, although even though I've been around digital cameras for quite a while now the whole larger f/stop=smaller opening and vise versa still has me going :?: from time to time.

To me it would be easier for a beginner to get their head around DOF and aperature settings if you were to say the 2 photos showing it off were taken at F3.5 for photo 1 and F10 for photo 2.
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Peterthecactusguy
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Post by Peterthecactusguy »

Harriet thanks for posting this. I will reference this from time to time to remember what I need to do.
:)
Here's to you, all you insidious creatures of green..er I mean cacti.
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