+

Lesson # 3

Types of Lens , Mega Pixel , Image Quality .

Subject:

Photography

Faculty Name:Partha Pratim Samanta

Deviprasad Goenka Management College of Media Studies (dgmcms.org.in)

FY BA

India’s premier Media -school

+Lens

A camera lens is an optical lens used in conjunction with a camera body and mechanism to make images of objects either on photographic film or on other media capable of storing an image chemically or electronically.

+How Lens Work

A lens gathers the rays of light coming from a scene and projects them as reversed images onto the film at the back of the camera. You can see this demonstrated below:

+ Types of Lens

Normal Lens

Tele Photo Lens

Wide Angle lens

+Types of Lens

The telephoto on the other hand allows the photographer to capture light from greater distances and make it appear to be closer than the scene really is.

Finally the wide-angle does the opposite of the telephoto lens, it make the scene seem farther away and expands the viewable area.

+Types of Lens

When a photographer speaks of the speed of his or her lens, they are simply referring to the measure of light that transmits through the lens to the film.

A larger aperture lens allows more light than a small aperture lens. This diameter is measured as an f-stop.

+Types of Lens

EF-S zoom- EF- S 10-18mm, EF- S 10-22 mm, EF- S 15-85mm, EF- S 17-55mm, EF- S 17-85mm, EF- S 18-55mm, EF- S 18-135mm, EF- S 18-200mm, EF- S 55-250mm

Ultra Wide Zoom EF-S 10–18mm, EF 16–35mm, EF-S 10–22mm, EF 17–40mm, EF-S 15–85mm.

Standard Zoom- EF-S 17–55mm, EF 24–70mm, EF-S 17–85mm, EF 24–105mm, EF-S 18–55mm, EF 28–135mm, EF-S 18–135mm, EF 28–300mm, EF-S 18–200mm.

Telephoto- EF-S 55–250mm, EF 70–200mm.

Standard Prime EF 70–300mm EF 40mm, EF 100–400mm, EF 50mm, EF 200–400mm.

+Types of Lens

Telephoto Prime Wide Angle Prime EF 85mm, EF 14mm, EF 100mm, EF 20mm, EF 135mm, EF 24mm, EF 200mm, EF 28mm.

Super telephoto Prime EF 35mm, EF 300mm.

Macro EF 400mm , EF 50mm.

+Zoom Lenses & Prime Lenses

A zoom lens is one where the photographer can vary the focal length within a pre-defined range, whereas this cannot be changed with a "prime" or fixed focal length lens.  The primary advantage of a zoom lens is that it is easier to achieve a variety of compositions or perspectives (since lens changes are not necessary).  This advantage is often critical for dynamic subject matter, such as in photojournalism and children's photography.

An inexpensive prime lens can generally provide as good (or better) image quality as a high-end zoom lens.

+Pixels & Megapixel

Digital cameras capture images as pixel elements, known as pixels.

Note :- Simply put, a megapixel is equal to one million pixels.

EXAMPLE :- 1 dot = 1 pixel 8 dot = byte Pixel 1024 dots = Kilo Pixel AND 1048576 dots = Mega Pixel And so on.

+Elements of picture quality

The number of megapixels is only one aspect relating to the quality of a camera or

Factors such as camera sensor and processor, and the optical quality of a lens, play equally important roles.

Other elements determine the quality of photos and prints. They include:

Good lighting of a subject Proper focus and exposure Image clarity (lack of blur due to camera shake or incorrect

shutter speed) Shooting at the highest resolution and quality camera

settings

+F-Length

The aperture range of a lens refers to the amount that the lens can open up or close down to let in more or less light, respectively.  Apertures are listed in terms of f-numbers, which quantitatively describe relative light-gathering area (depicted below).

Note: Above comparison is qualitative; aperture opening (iris) is rarely a perfect circle, due to the presence of 5-8 blade-like lens diaphragms. That larger aperture openings are defined to have lower f-numbers (often very confusing). 

+Depth of Field

The depth of field (DOF) is the portion of a scene that appears sharp in the image. Although a lens can precisely focus at only one distance, the decrease in sharpness is gradual on either side of the focused distance, so that within the DOF, the unsharpness is imperceptible under normal viewing conditions.

+Depth of Field

+Take Away Tips

Many cameras use interchangeable lenses.

When a photographer speaks of the speed of his or her lens, they are simply referring to the measure of light that transmits through the lens to the film.

Think Experiment Move Wait Rule of Thirds