Flashcards in Chapter 8 Deck (35):
Three basic forms of communication
• The camera needs several lenses called elements to duplicate the complex working of the eye.
• A lens is two prisms joined together.
• If the prisms are joined at their apexes they from a concave lens that converges the light to a single point.
• If joined at the base, they form a convex lens that converges the light to a single point.
• Distance from the optical center of the primary lens to the point where the light converges on the focal plane.
• Focal length determines the field of view of the lens.
• Short focal length has wide field of view is called wide-angle lens.
• Long focal length has a narrow field of view and is called telephoto lens.
Different Types of Lenses
• Wide Angle: 4.5mm to 25mm (allows more control)
• Normal: 25mm to 75mm
• Telephoto: 75mm or longer
Zoom vs Prime Lens
• Advantage of zoom lens over prime lens (fixed lens) is that the focal length can be set at any point with the parameters for that lens.
• Prime lenses are generally of a higher quality than zoom lenses and are used on DSLRs and high-end cameras.
• The point at which the light rays that pass through a lens converge and are in focus
Depth of Field
• The range of acceptable focus in front of and behind the plane of focus
• 3 factors affecting depth of field: Focal length, iris opening, distance from camera.
• As focal length increases, the dept of field decreases
• As the iris is opened up, the depth of field decreases.
• As the lens is focused on objects closer and closer to the camera, the depth of field also decreases.
• Minimum Object Distance- The limit of how close a lens can focus.
• 4:3 (analog), 16:9 (like our normal human way of seeing things)
• Overlapping metal leaves or fins that rotate to make the hole smaller or larger. Controls the amount of light passed on to the focal plane.
• F-stops are used to measure the speed of a lens.
• Fast transmits a large amount of light.
• Slow transmits smaller amount of light.
Optical Groups of Zoom Lenses
• Focusing group- gathers light into a sharp, clear image.
• Variator group- Moves inside the lens to change the image size from wide angle to telephoto.
• Compensator group- Moves with the variator group to keep the image in focus & reduce aberrations caused by the first 2 groups.
• Prime lens group- Focuses the image on the recording surface, such as film or a TV camera chip.
• 2x range extender- doubles the focal length however it is limited in low-light situations.
Light Quality Control
• Ultraviolet filter- protects the lens from scratches, dirt, etc.
• Hood- Prevents direct light from striking the front element.
• Lens Flares- Circular patterns or reflections in the lens
• Color enhancement- change the perceived color of light
• Diffusion- reduce the sharpness and/or contrast of the picture
• Special effects- Do everything from creating multiple images to split screen. Most of these things can be done in post production.
Proper Lens Care
• Loose dirt or dust can be blown or brushed away with a soft photo brush or an air blower.
• Do not use your shirt, tissue, or mouth.
• The 1st thing and image passes through in a network quality camera.
• Contains basic filters (clear, color correction, and light reduction)
CCDS and CMOS
• CCDS more expensive, less susceptible to noise in the picture, require more battery power
• CMO (Complementary metal oxide semi conductors)
• National Television Systems Committee- reference system used in the U.S. from 1940s until 2009.
• Used 525 lines of resolution and scanned at 59.85 fields per sec.
• Advanced Television Systems Committee
• 16 x 9, 1080 lines of resolution
• Power Switch- Gives power
• Standby- Used when you don’t need to operate it, but want to start up quick.
• Save on- Gives you a pic in the viewfinder, but prevents the VCR’s tape servo motors from coming up to speed.
• Camera bars- Makes the output of the camera either the picture or the color bar generator contained within the camera.
• Gain switch
• White balance, black balance
• Viewfinder shows exactly what the recorder sees
• Can show Zebra bars, which appear over parts of the picture to display the exposure level.
• Normal is 1/60 of a sec
• Fast shutter speeds allow for slow-motion pictures & freeze frames, but show a strobe effect when playback at the normal amount of frames per sec
• Needed to make adjustments on the electronics of a camera.
• Checks the color or chroma of the TV signal.
• Ex: If reds don’t look right this will tell whether it’s the operators eye, the TV set, or the camera that is wrong.
Type C Format
• One inch tape format became the studio standard for years, but wasn’t practical in the field.
• Had good resolution and allowed special effects like slow motion without distortion.
ntroduced in 1982 dominated the professional world of videotape for portable recording.
• Developed in the late 1990’s for lower-end professional or industrial market.
• All DV formats use an 8-bit 4:1:1 sampling rate.
• Many camcorders have he ability to record directly to a memory card.
• SD Cards (secure digital)
• CF (compact flash)
• Advantages: Has no moving parts and is not sensitive to extreme temperature, vibration, or shock. Rewritable.
• Allows each frame of the video to be numbered. When played back scenes or shots can be located by their time code.
• Always check battery 1st.
• Tape decks (Is the record tab in place?)
• Know the switches and buttons on equipment
• Head cloggs
Proper Battery Care
• Amps = watts/volts
• Ideal temp is 75 degrees
• No leak icepacks help cool camera and battery
• Fluid head- Acts as dampening agent to resist movement so that the camera doesn’t jerk.
• Pan/tilt locks
• Tripod legs
• Forward and back movement of the entire camera unit
• Camera mount that allows it to be raised or lowered