What is ISO?Film Sensitivity (ISO): (InternationalOrganization for Standardization) In traditional (film) photography ISO (or ASA) was the indication of how sensitive a film was to light. It was measured in numbers (you’ve probably seen them on films – 100, 200, 400, 800 etc). The lower the number the lower the sensitivity of the film and the finer the grain in the shots you’re taking.

In Digital Photography ISO measures the sensitivity of the image sensor. The same principles apply as in film photography – the lower the number the less sensitive your camera is to light and the finer the grain.

Film Sensitivity (ISO): Some films are moresensitive to light than others.

Three ways to control light

Aperture: How much light gets in

Shutter speed: How long light is let in

ISO: Sensitivity of image device

Image Sensor Size

An image sensor is a device that converts an optical image into an electric signal. It is used mostly in digital cameras and other imaging devices. An image sensor is typically a charge-coupled device (CCD) or a complementary metal–oxide–semiconductor (CMOS) active-pixel sensor

Exposure:Exposure maybe define as a number line, in where the negative numbers are under exposure and the positive numbers are the over exposure. And the middle number between these two kinds of numbers (0) is correct exposure..

Exposure is the result of mixing 3 major elements of photography. These major elements are:(1)ISO (2)Shutter speed (3)Aperture

Correct Exposur

A correct exposure is one where the photograph is not overexposed orunderexposed.

Modes

TV / S: Shutter priority Exposure

AV / A: Aperture priority Exposure

M: Manual Exposure

P: Programmed

Auto Exposure

UnderexposureDefinition: Underexposure in photography refers to an image where too little light was recorded. The degree of underexposure will determine how dark a photo is. Slight underexposure can lead to a pleasing deepening of color saturation but more pronounced underexposure makes and image too dark for subjects to be seen clearly. A photographer knows if the image is underexposed or not by using his/her light meter.

Example of Over Exposure and Under Exposure

Exposure bracketing

In digital photography, bracketing is the technique of shooting a number of pictures of the same subject and viewpoint at different levels of exposure. Half or one f-stop (+/-) differences are usually selected depending on subject.

Example of exposure bracketing

–4 stops –2 stops +2 stops +4 stops

Alternative Exposure

Alternative Exposure is equivalent process like Bracking exposure. In alternative exposure photographer take photos in different exposure and select one exposed photograph and delete other exposed photographs.