What is ISO in photography?

Selecting the ISO on a Samsung smartphone

“ISO” is the acronym for “International Standards Organisation”.ISO standards  are recognized worldwide and conforming to them, although on a voluntary basis, is a quasi pre-requirement in many business domains. In the field that interests us, i.e. photography, ISO refers to the sensitivity of the digital sensor to light. In the past, in the United States, film manufacturers were using the …

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What is “Exposure” in Photography?

Illustration of three factors affecting the exposure. Image © Charles Martel 2015

In photography, “exposure” is a key concept. The “exposure” is the amount of light that the photographer, or the camera in automatic modes, allows to fall on the sensor, at the moment of image capture. A correct exposure , i.e. enough light hits the sensor, but not too much, is crucial to the creation of a quality image.

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What is “depth of field” in photography?

Depth of Field

In photography,  “depth of field” (DOF) is the depth of the sharp area in the image, both in front of and behind the main subject of the image, the subject on which the focus was made. Here is a diagram illustrating the concept:

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What is “focus” in photography

Yellow bird out of focus

In photography, the term “Focus” means the point of maximum sharpness in the photo. Normally, the focus will be made either manually or automatically, so that the main subject of the picture is as crisp and clear as possible.

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What’s a megapixel?

Image reduced to 10% of its size and then re-expanded to its original size.

A megapixel (mp) is simply one million (1,000,000) pixels or dots, forming a photographic image. A 1 mp image can be of several formats, i.e. that several combinations of width x height can give the same number of megapixels. 5000×200 pixels, 2500×400 pixels or 1250×800 pixels are all 1 mp images.

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What is image resolution?

Simulated image, resolution 64 x 48 (actually 640 x 480). © Charles Martel 2015

An image’s resolution  is a count of the number of points or dots composing it. A Mosaic of Dots! A digital image is like a mosaic, e.g. an image composed of many colored dots, called “pixels”, a contraction of the words “Picture Elements”. A million pixels is a Megapixel (more details in an upcoming article).

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What is a digital sensor?

Bayer grid (enlarged)

A sensor is an electronic chip A digital sensor is essentially an electronic “chip”, that has the particularity of being sensitive to light. The sensor plays the role previously assigned to photographic film, i.e. to capture the image. It does it, however, in an entirely different way compared to film. And thousands of times more …

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What is a zoom lens?

Leica Zoom Lens Lumix FZ1000

The zoom lens is a complex lens that allows the photographer to vary the focal length at will, within a predetermined range. For example, a zoom lens can have a range from 24mm (i.e. wide angle) to 400mm, a fairly powerful telephoto.

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What is a telephoto lens?

Marche sur le Mont-Royal avec zoom C Martel Photo

A telephoto lens is a lens whose focal length is longer than normal focal length (for the sensor size) and therefore has a magnifying power on distant objects, just like binoculars or telescopes.

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What is a wide-angle lens?

wide-angle lens

A wide angle lens, is the exact opposite of a telephoto lens. It is a lens whose focal length is short.

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