Lesson 1: The Art and Physics of Photography Basic Photography MITSAA Spring 2003 Rob Zehner

General Info Instructor: Rob Zehner Course web page: Meeting time: 7: :00 p.m. every Wednesday We will meet in front of the SAA office

Outline How the camera works –lens –shutter –aperture –film Some rules of thumb for good photos

The Camera image lens aperture virtual image

The Lens Purpose: to collect light from the sample and focus it on the film plane Focal length: distance from the lens to the film plane (for a single-element lens) when focused at infinity –Longer focal length = more magnification

The Shutter Prevents light from reaching the film Opens to allow light through In most cameras, the shutter is actually two pieces of cloth or metal that move across the film plane, one after the other Shutter speeds are usually reported as reciprocal seconds, e.g = 1/1000th sec.

The Shutter, continued Shutter speed determines relative effects of motion –Slow shutter speeds = blurry images –Fast shutter speeds = stopped motion –Rule of thumb: 1/60th or faster will eliminate the effects of shaky hands Also determines film exposure –2X shutter speed = 1/2 the light to the film –1/2 the shutter speed = 2x the light to the film

The Aperture Placed at the focal point of the lens Typically a circular opening Diameter of circle determines amount of light that gets to the film Reported as f-number - ratio of focal length to aperture –Larger f-number = smaller opening

The Aperture, continued Size affects “depth of field” - distance in front of and behind the focal plane that is in focus –Small apertures (large f number) = greater depth of field Size also affects film exposure –Increase of 1 stop (x 1.414) = 1/2 as much light –Decrease of 1 stop (  1.414) = 2x as much light

The Film The film’s job is to detect light –Photons hit the film and promote a reaction Film speed is typically reported in ASA –Higher ASA = “faster” film - needs less light –Doubling ASA = 1 stop less light needed Rule of thumb - “sunny f16 rule” –Under bright sun, use f16 and 1/ASA shutter Generally, film with a higher ASA is grainier

The Photographic Process Film exposure –Photographic emulsion held inside a camera is exposed to light from the subject Film developing –Latent image on the film is processed to give a permanent image with negative optical contrast Printing –Light is projected through film onto photographic emulsion to produce an enlarged latent image Print developing –Latent image on photographic paper is processed to give a permanent, viewable image (positive tone)

Alternatives Transparencies (aka slides) –Photographic film can be processed to produce a positive-tone image on film Internegatives –Film images can be transferred at 1:1 enlargement onto other film for creative effects, or to produce a print from a positive transparency Direct-positive printing processes –Certain print processes can produce a positive print from a positive transparency Digital ! –Scanning, digital printing, output to film, etc.

The Rule of Thirds

Other tips for good photos Use natural light –Avoid on-camera flash as much as possible Find new perspectives –Move around –Take horizontal and vertical shots Find converging lines Play with negative space Take candid portraits When in doubt, bracket exposures