6 098 Digital and Computational Photography 6 882 Advanced Computational Photography Photography Survival Kit Bill Freeman Fr do Durand MIT EECS Focal length in mm Determines the field of view wide angle 30mm to telephoto 100mm Focusing distance Which distance in the scene is sharp Depth of field Given tolerance zone around the focus distance that is sharp Aperture in f number Ratio of used diameter and focal lens Number under the divider small number large aperture e g f 2 8 is a large aperture f 16 is a small aperture Shutter speed in fraction of a second Reciprocity relates shutter speed and aperture Sensitivity in ISO Linear effect on exposure 100 ISO is for bright scenes ISO 1600 is for dark scenes Quantities aperture focal length focus distance sensor size lens depth of field field of view Focal length 30mm wide angle 50mm standard 100mm telephoto Affected by sensor size crop factor 24mm 50mm focal length 135mm field of view Exposure Aperture f number Expressed as ratio between focal length and aperture diameter diameter f f number f 2 0 f 2 8 f 4 0 f 5 6 f 8 0 f 11 f 16 factor of sqrt 2 Small f number means large aperture Main effect depth of field A good standard lens has max aperture f 1 8 A cheap zoom has max aperture f 3 5 Shutter speed In fraction of a second 1 30 1 60 1 125 1 250 1 500 factor of 2 Main effect motion blur A human can usually hand hold up to 1 f seconds where f is focal length Sensitivity Gain applied to sensor In ISO bigger number more sensitive 100 200 400 800 1600 Main effect sensor noise Reciprocity between these three numbers for a given exposure one has two degrees of freedom Depth of field The bigger the aperture small f number the shallower the DoF Just think Gaussian blur bigger kernel more blurry This is the advantage of lenses with large maximal aperture they can blur the background more The closer the focus the smaller the DoF Focal length has a more complex effect on DoF Distant background more blurry with telephoto Near the focus plane depth of field only depends on image size Hyperfocal distance Closest focusing distance for which the depth of field includes infinity The largest depth of field one can achieve Depends on aperture Equipment Do get an SLR compacts are way too limited Don t worry about brand Don t worry about the body get the cheapest one Worry about lenses Zooms are convenient but quality can be a problem avoid the basic zoom but the one above is usually great Maximum aperture matters the smaller the number the better Get a prime in the 35 85mm range cheap high quality wide aperture 50mm f 1 8 both Canon Nikon Get a tripod Get an external flash if you want to take event pictures And orient towards ceiling Good flash photography is very difficult Count 1k for camera standard zoom 50mm Nikon Tends to be a tad cheaper D50 is a great body D70 is a little better 18 70 55 200 is surprisingly not so bad and super cheap Get the 50mm f 1 8 Canon Rebel XT or 20D 17 85 70 200 f 4 0 amazing lens 50mm f 1 8 100mm f 2 8 macro great also for portraits Other brands Not as big a range future not always clear see Minolta have been slower to get to digital SLR Olympus Good system but smaller sensor Konica Minolta Just announced they stop photography Pentax Good entry camera Sigma Intriguing sensor Foveon Fuji One trick pony the sensor Nikon body Sony Interesting hybrid the R1 Very silent good images crappy viewfinder no interchangeable lenses Shooting Use aperture priority work on depth of field Change your viewpoint Don t center things Learn to adjust ISO Shoot raw Check your histogram Editing Photoshop Crop to improve composition Manage contrast using curve and adjustment layers Sharpen a bit Convert to black and white with gradient map