Guide To The Measurement Of Exposure in The Optical Viewfinder

Guide To The Measurement Of Exposure in The Optical Viewfinder

When you approach photography, especially with a SLR, one of the things most difficult to handle it is the exposure. Many beginners (and not only) before taking a photo, keep it, then playing with the settings, click the second picture, evaluate the results and so on. A method to attempts made possible by the advent of digital, but definitely not stylish, not at all precise and fast. Knowing the exposure, as we saw in a previous article, it is essential to get good pictures, but even more important is to understand how the measurement of exposure in the optical viewfinder.
Exposure The Basics

As already explained previously in the article concerning the exposure (even here), this refers generically to the amount of light reaching the camera’s sensor More light gets, the brighter the resulting image. Conversely, the less light reaches the sensor, the lower the brightness of the image.

The amount of light hitting the sensor is a function of shutter speed and aperture. Shutter speed is measured in fractions of a second (1125, 150, etc.) and it is time that the shutter is open for passing light.

Since the number is a fraction, the lower the denominator, the longer the exposure time. For example, 1200 of a second is a much shorter amount of 110 of a second. As a result, a shutter speed of 1200 of a second will leave in a lot less light and produce images much darker than a shutter speed of 110 second. Also note that the longer the exposure, the moving objects will become blurry.

The aperture setting controls the amount of light reaching the sensor by varying the size of the opening through which the light passes. This is expressed in terms of the focal length (f  x). The lower the number associated with the denominator of the focal length, the larger the size of the hole, which means more light enters the camera and therefore a bright image.

I also remember that the small denominator indicates a small focal length and a shallow depth of field. This means that the area of the image that is in focus is quite large with f  11 but with small f  3 or lower.
Exposure in the optical viewfinder ISO

The ISO setting also affects the brightness of the image in combination with the quality. Without going into the complexity of the electronic sensor of the camera (I refer you to Article relative), suffice it to say that the higher the ISO value, the brighter the resulting image. Unfortunately, with increasing ISO also increases the chromatic noise, which dramatically reduces the quality of the picture.

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