The larger, or front lenses of Binoculars. The Objective Lens Diameter is the size of the outer (front) lens in millimeters. A 7x35 binocular has a 35mm objective lens. This helps determine how much light enters the binocular, although image brightness still depends on the size of the exit pupil.
Field of View
Is the width of the area (in degrees) that can be seen at a given distance (usually measured at 1000 yds). Sometimes called, "Angular Field" a large field of view permits you to see a large area at one time, and it also enables you to follow a moving subject with ease The smaller the magnification the greater the field of view.
When we refer to "res" or "resolution" in relation to a cameras recording sensor, we are talking about how many picture elements or pixels are present on the sensor. These dyas the bigger the number does not automaticly make for a better picture. Other factors come in to play, such as the lens quality, light and chromatic aberations that can cause "colour fringing". It is also true that if a huge number of pixels are present on a small chip, they can interfere with each other causing noise on your images.
Sensor (CCD or CMOS)
CCD (Charged Coupled Device): A light-sensitive device that collects electrical charges in a potential well proportional to the incident light. The charge is then read out digitally CMOS (Complimentary Metal Oxide Semiconductor): An electronic component uses for RAM and fast data switching. CMOS semiconductors are made of two metal-oxide field effects transistors for high speed and lower power use. However they can be damaged by static electricity.
Also called "Power", this number reflects how many times the image is magnified. For example, through a 10x binocular the image will appear 10 times larger than with an unaided eye, an 8x will magnify only 8 times. With 8x power an object which is 800 feet away will appear as if it was only 100 feet away.
Zoom (Optical & Digital)
Optical: Uses the optics (lens) of the camera to bring the subject closer.
Digital: Enlarges a portion of the image, thus 'simulating' optical zoom. In other words, the camera crops a portion of the image and then enlarges it back to size. In so doing, you lose image quality.
Measured in mm, this is the diameter of the beam of light leaving the binocular eyepiece, and determines how much light the eyes receive. Larger exit pupils provides brighter images. To calculate Exit Pupil, divide the objective size by the power. For example, the exit pupil of a 7x42 binocular is 42 divided by 7, or 6mm.
Optical: The optical viewfinder on a digital compact camera consists of a simple optical system that zooms at the same time as the main lens and has an optical path that runs parallel to the camera's main lens.
Optical SLR: The optical viewfinder of a digital SLR shows what the lens will project on the sensor via a mirror. Also refered to as TTL (Through The Lens).
Electronic (EVF): An electronic viewfinder functions like the LCD on a digital compact camera and shows in real time what is projected onto the sensor by the lens.
Digital cameras have an ISO rating indicating their level of sensitivity to light. The sensitivities can range from 50 to 100, 200, 400, 800, 1600 or even 3,200. When increasing the sensitivity, the output of the sensor is amplified, so less light is needed. Unfortunately that also amplifies the undesired noise.