Learning about camera lenses

Aperture:

Aperture is referred to the lens diaphragm opening inside a photographic lens. The size of the diaphragm opening in a camera lens REGULATES amount of light passes through onto the film inside the camera the moment when the shutter curtain in cameraopens during an exposure process.

camera-apature-image

ISO: International Standards Organization

ISO on a camera stands for International Standards Organization, which is the governing body that sets sensitivity standards for sensors in digital cameras. ISO settings determine how sensitive the camera’s sensor is to light, while taking various types of photos.

iso-01

 

Exposure triangle:

The exposure triangle is a common way of associating the three variables that determine the exposure of a photograph: aperture, shutter speed, and ISO. One must balance all three of these to achieve a desired result, an adjustment of one requiring adjustments of at least one of the others

DCIM100GOPRO

Depth of field:

Depth of field. … In optics, particularly as it relates to film and photography, depth of field (DOF), also called focus range or effective focus range, is the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image.

 aperture-depth-of-field.jpg
aperture and DOF.jpg
lens-comparison

Shutter speed:

Slow shutter speeds allow more light into the camera sensor and are used for low-light and night photography, while fast shutter speeds help to freeze motion. Examples of shutter speeds: 1/15 (1/15th of a second), 1/30, 1/60, 1/125. Aperture – a hole within a lens, through which light travels into the camera body.

shutterspeed

F/stops:

Photographers set their exposure using a combination of shutter speeds and f/stops to get the correct amount of light on the sensor (or film). The shutter speed regulates how long the sensor is exposed to light coming through the lens.

fstop

Pros and Cons of lenses:

Standard Zoom: These are the most common type of lenses and practically all the kit lenses bundled with cameras fall into this category. The most popular is the 18mm-55mm lens, which is good for general purpose photography and is commonly used by amateurs and first time photographers. A few years ago, the quality of these lenses was not good enough and earned a bad name for their manufacturers. Realizing this, the camera makers started bundling much better versions that give very decent results.

Zoom: These are long-range lenses, which have longer focal lengths as compared with the standard zoom lenses. The popular lenses are 55mm-250mm, 70mm-300mm, and 75mm-300mm. These lens are used by semi professionals and serious photography enthusiasts to shoot animals and birds.

Wide Angle: These lenses are most popular with landscape and nature photographers. The common wide-angle lenses are 10mm-20mm, 12-24mm, and 11mm-16mm. Another variant of wide-angle lenses are called fish-eye lenses. They give maximum angle of view and in that process distort the view in a circular fashion.

prime-lens-on-table

Prime lenses: All the above lens types are used by amateurs, serious hobbyists, and semi-professionals. Professionals however would use prime lenses.

Prime lenses advantages:

butterfly prime lense.jpg

The most obvious advantage is image quality. Prime lenses are bought by professionals to obtain the best quality photographs from their camera gear. The general parameters on which the image quality is tested are:

1) Sharpness: Subjective quality of an image indicating clear or distinct reproduction of detail: associated with resolution and contrast. * Hence a sharp lens is an optic capable of giving sharp images. 

2) Distortion: a warping or transformation of an object and its surrounding area that differs significantly from what the object would look like with a normal focal length, due to the relative scale of nearby and distant features.

3) Vignetting: In photography and optics, vignetting (vignette“) is a reduction of an image’s brightness or saturation at the periphery compared to the image center.

4) Chromatic aberration: Chromatic Aberration, also known as “color fringing” or “purple fringing”, is a common optical problem that occurs when a lens is either unable to bring all wavelengths of color to the same focal plane, and/or when wavelengths of color are focused at different positions in the focal plane.

Below is an example of colour fringing.

colour fringing.jpg

In all prime lenses, the test results show the highest ranking for the sharpness and lowest values for the other three parameters: distortion, vignetting, and chromatic aberration.

As professional requirements demand the best images that can be used by clients, it is prudent to invest in a prime lens as per the photographic assignments and budget.

Prime lenses disadvantages:

The biggest disadvantage of using a prime lens is the fixed focal length. You will experience the limitations when you start shooting with a prime lens. There is no zoom, which implies that you have to compose the frame by moving further away or by going nearer to the subject.

Another drawback of the prime lens is the price factor. Prime lenses, barring the very basic models, are much more expensive than their zoom counterparts.

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