Upload
rajnishkumawat
View
442
Download
4
Tags:
Embed Size (px)
Citation preview
CAMERA LENS
Presented By:-
RAJANISH KUMAWAT
10ESOEC092
4TH YEAR, VIITH SEM
APRACTICAL TRAINING
ATDOORDARSHAN KENDRA, JAIPUR
Topic Covered:-
DOORDARSHAN
KEY ASPECTS:-
Doordarshan is an Indian public service broadcaster. It is owned and operated by Prasar Bharati Broadcasting Corporation. It is one of the largest broadcasting organisations in India in terms
of the studio and transmitter infrastructure. It was started in Delhi on 15 September 1959 as experimental,
and its regular transmission started in 1965. Its Head office is located in New Delhi, India.
KEY ASPECTS:-
The DD provides television, radio, online and mobile services throughout India.
Presently, Doordarshan operates 21 channels including DD National, DD News and DD Sports.
The network features some original programming, such as dramas, comedy-series, talk shows and re-runs of popular TV shows from other Indian television channels. Live Coverage of national events like Independence Day, Republic Day Celebrations, Budget Presentation and other happenings of national and international importance are regularly carried on this channel.
DD RAJASTHAN
KEY ASPECTS:-
DD Rajasthan is a state owned TV channel telecasting from Doordarshan Kendra Rajasthan.
On 1 August 1975, the first television broadcast was viewed by the people of Rajasthan under the Satellite
Doordarshan Kendra in Jaipur was set up on 1 June 1987 at Jhalana Doongri and transmission started on 6 July 1987.
Initially only 30 minutes of programming produced by this Kendra and this was gradually increased. Presently the
Kendra originates about four hours of programming daily. The channel covers 79% by population and 72% by area of
Rajasthan.
DOORDARSHAN RAJASTHAN
A TV Camera consists of three sections:-
a)A Camera lens: It selects a certain field of view and produces a
small optical image of it on the face plate of pick up device.
b)A transducer or pick up device: To convert optical image into an
electrical signal. It is mounted inside the main head of camera.
c)View Finder:- It shows a small video image of what the lens is
seeing.
Television Camera lens
Topic of interest
FUNCTIONS OF LENSES:
Primary function of lens is to produce a sharp image of object on the face of camera imager.
To determine the magnification and size of the image.
To decide field of view.
NOTE:-Changing distance from the lens to object changes the size of the image and position of the image plane
objecto
objecto
objecto
Real image
Real image
Real image
lens
lens
lens
f
f
f
FOCAL LENGTH
Focal length is the distance between optical center of the lens (and not the physical center) and the focal point.
Focal point is the point at which the light rays converge at the rear of the lens to produce perfectly focused image.
In a video camera it is the distance between
face of the pick device and optical center of the
lens.
Focal length will decide the amount of image
magnification and field of view.
Wide angle
Narrow angle
Optical center
Image plane
Image plane
Focal length
Focal length
(Short)
(Large)
BASIC TERMS IN CAMERA LENSResolution: Number of pixels captured by image sensor.Focus: To focus objects at various distances
3,4,5,7,10,15,30, infinity, in feetZoom: To take long(lowest focal length) and tight shot (Highest focal length)Aperture: To control the amount of light entering
cameraF-stop: 1.4, 2.0, 2.8, 4, 5.6, 8, 11, 16, 22, Back Focus: To keep long shot in focus while zooming out.Macro: To focus an object lying within Minimum Object Distance.
Resolution: Resolution is number of pixels captured by the image sensor.
Higher Resolution Image300 ppi
Lower Resolution Image72 ppi
SHUTTER
All cameras have a shutter between the lenses at the front and the film at the back.
The shutter is mostly closed so that light cannot get to the film.
When you press the button to take the photo, the shutter opens briefly and then closes again.
The time for which the shutter is open is called the shutter speed. The shorter the time, the less light gets in.
So, a shutter speed of 1/60th of a second
lets in half the amount of light than a speed of 1/30th of a second.
Focus
Poor focus Poor focus
Average focus Good focus
Variable Focal Length Lens or Zoom lens
Zoom lens has variable focal length and changes focal length continuously without losing focusing . Typical zoom range from 12-72mm.
Zoom Ratio 6:1 can also be expressed as 6x. The zoom ratio can be 10x, 12x, 15x, 19x etc.
The greater the focal length, the narrower will be the field of view and the narrower the depth of field.
Action of Zoom Lens
Focal length 165mmFocal length 80mm
Focal length 40mmFocal length 8.7mm
APERTURE
Aperture is required to control the amount of light entering the camera.
The amount of light is specified by F-number (=f/D).
The stop ring of the lens is marked with series of numbers with a ratio of under-root of 2: 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22
Aperture with various openingsFully Closed
Fully Open
Partially open
Half open
F-stop=2.8 F-stop=4.0
F-stop=5.6 F-stop=8.0
Effect of Aperture (Iris)
F-stop=11 F-stop=16
F-stop=22 Iris Fully Closed
Effect of Aperture (Iris)
Maximum to minimum distance within which the objects remain in focus
With aperture fully opened With aperture partially open
Depth of field
Lens Aperture: Smaller the aperture or larger the f-stop number, more the depth of field. It is because with less aperture opening the light rays from the outer edges of lens are cut off, narrowing the maximum convergence angle at the focal point.
Camera to subject distance: Larger the distance of the subject from the camera, greater is the depth of the field
Focal length of the lens: As you increase the focal length of the lens (i.e. narrowing it’s angle of view), the image size increases, but the relative depth of field decreases. Lens stop and focusing distance remaining constant.
Factor Affecting Depth of Field
Close-up or Macro lens enables us to take photographs of the objects closer than MOD. In Macro mode, zoom lenses cannot zoom.
MACRO
Without macro With macro
Wide Converter
A wide converter is useful for getting a large number of people into one scene in a narrow space
Close-Up Lens
A close-up lens is effective for close-up photography of, for example, flowers and insects.
UV Filter, Skylight filter
A UV (ultraviolet) filter is nearly colorless. It absorbs short-wavelength ultraviolet rays that the naked eyes cannot see.
Extender
Extender is mounted between the camera and the lens to enlarge the images of the subjects, or shoot more distant subjects