1 Digital Cameras Consumer digital cameras have been around since 1995 What features make a good camera? How do we optimize good features with a limited budget?

1 Exposure How many photons contribute to each pixel? – More is better! Exposure is a combination of several factors – Aperature Size – Shutter speed – Lens size – Sensor Sensitivity – Sensor size (bigger is generally better)

1 Lens The lens gathers light The lens focuses the image Sharpess of the image depends on the lens Larger lenses gather more light Smaller lenses allow for a smaller camera

1 Lens Focal Length Focal length – Macro have short focal lengths Allow imaging small objects – Normal have intermediate focal lengths Most cameras have one – Telephoto have large focal lengths Allow imaging far away objects

1 Field of View

1 Vignetting A gradual fading of the image away from the center Caused by lens optics

1 Optical Zoom Changes lens focal length More lenses can lead to glare and loss of sharpness Large zoom can benefit from image stabilization

1 Digital Zoom Digital zoom extracts a region Similar to cropping Use optical zoom if possible

1 Shutter Speed Controls how long the sensor is exposed Short – Need lots of light – Good for moving objects Long – Good for stationary objects – Need less light

1 Aperture Controls amount of light entering camera Provides field of view – Small aperture acts like a pinhole Entire image in focus – Large aperture Narrow range in focus Provides emphasis on foreground objects

1 Viewfinder Allows us to identify the content of the image Optical – Through the lens – Off axis Electronic – Small – Full-size

1 Camera Display Small Screen Review of images Camera control Viewfinder

1 Sensor Acquires the image Electronic equivalent of film CCD – Charge-coupled device CMOS – Complementary Metal Oxide Semiconductor

1 CCD vs. CMOS

1 Mosaic vs. Foveon

1 Analog to Digital Conversion Electronic cameras convert energy from an analog signal to digital – Discrete in time – Discrete in amplitude

1 Quantum Noise Based on the number of photons Variation is the square root of the number of photons

1 Other Noise Electronic – Heat – Cheap Electronics – Design Senosor – Bad pixels Hot Cold – Bad line See

1 Camera Speed Time to read sensor Time to write image to media Faster is better

1 Compression JPEG JPEG2 Is the image always compressed?

1 Data Storage Media Physical device where images are stored Tradeoffs – Physical size (smaller is better) – Speed (faster is better) – Data size (larger is better) – Cost per GB (more is better) – Reliability How permanent is the storage? What is the failure rate? – Availability What other devices can use the media?

1 Noise Statisitcal variations in the pixel values Noise obscures detail

1 Battery Power Provides camera with power Disposable – Costly in long run – Low power Rechargeable – Lithium – NiMH Important question – How many pictures can be taken on one charge?

1 Camera Settings What special features does the camera provide? – Shutter priority – Aperture priority – Movies – Red-eye reduction – Delayed shutter

1 Connectivity How does the camera interface with computers? – USB – Firewire – Serial – Removable media

1 Flash Does camera use a flash? – Internal – External

1 Tripod Holds camera Useful for – long exposures – Repeated shots

1 Carrying Case Holds camera and other supplies – Tripod – Batteries – Recharger – Manual – Extra media

1 Hybrid Cameras Digital camera that can directly print to polaroid film any desired photos Preview of film images before processing Dual film/digital camera where one can easily switch between the two modes A 35 mm cassette that has the same form factor as a film camera, yet acquires digital images Direct digital conversion of film during processing