Thursday, December 4, 2008

How Angle of View, Depth of Field & Perspective changes with change in Focal Length

Lets discuss a bit about relation of lenses with the focal lengths supported by them. Basically we have three basic lens types, determined by the focal length (measured in millimeters) of the lenses:

Normal. A normal lens shows most accurately what a normal human eye will see. 50mm is a typical normal focal length. The 50mm is the most popular and versatile lens. The quality is excellent while also being inexpensive. It is smaller and lighter, and the aperture allows photographs to be taken in low-light situations.

Telephoto. A telephoto lens brings the background closer. Longer-than-normal focal lengths such as 70mm and 300mm are typical for a telephoto lens. Since a telephoto lens will bring the subject up close, it is popular for sports photography.

Wide. A wide lens captures a wider expanse of the background than what the human eye will see. Shorter-than-normal focal lengths such as 24mm and 35 mm are typical for a wide lens. Wide lenses are popular for landscape photography and large group shots.

We also categorize lenses in two broad categories Fixed focal length & Zoom Lenses. Fixed/Block lenses are considered as quality lenses as compared to zoom lenses because Zoom lenses have optical errors due to extra lenses...

***How Angle of View, Depth of Field & Perspective changes with change in Focal Length***


Increases with decrease in Focal Length (>46 Degree)<<<<-----50MM (46 Degree) ------>>>> Decreases with increase in Focal Length(< 46 Degree)


Increases with decrease in Focal Length<<<<-----50MM ------>>>> Decreases with increase in Focal Length


Exaggerated Perspective<<<<-----50MM ------>> 80MM(Normal)----->> Diminished

- Normal Lens : 46 dgree angle of view : 50 MM
- <46 : Telephoto Lenses : Icreases DOF : Greater than 50 mm
- >46 : Wide-Angle Lenses : Decreases DOF : Less than 50 mm

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