Comparing Regular Film to Digital Photography Film can resolve about 4000-6500 pixels per inch. ........... A piece of 35 mm film is about 1.5 inches in width, so it can contain about 6000 - 9750 pixels along its length. It is about 1 inch in height and this dimension can handle between 4000 - 6500 pixels. The total resolution of a 35 mm negative or slide would then be between: 4000 x 6000 to 6500 x 9750 which means ... 6000 X 4000 = 24,000,000 pixels (24 Megapixels) 9750 X 6500 = 64,000,000 pixels (64 Megapixels) Information take from: http://www.theimage.com/photography/photopg1.htm

Technology Resolution Flat bed Scanner <$200 1600 x 3200 DPI (Epson) 35 mm Film Scanner < $1000 2900 DPI (Nikon) Digital Camera <$200 1600 x 1200 (2 megapix) (Olympus) Digital Camera < $500 2400 x 1800 (4 megapix) (Fuji) Digital Camera <$1000 2560 x 1920 (4.9 megapix) (Minolta) Photo CD 6144 x 4096 (Pro) 3072 x 2048 (consumer) (Kodak) The least expensive introduction to digital photography is either through a low cost scanner or a low cost digital camera. Suffice it to say, that an under $200 scanner can produce higher resolution images than the same priced digital camera or for that matter even higher priced cameras. Photo CD from Kodak uses a special very high resolution film scanner (Drum Scanner) to digitize the original negatives or transparencies

To capture the proverbial "perfect" image, traditional photography relies on three things: 1.) Film Characteristics 2.) Shutter Speed 3.) Aperture (f-stop) (aka .. light intensity) Film speed is a function of light sensitivity, but there are two other important characteristics also based on the speed and film base. Resolution is related to film speed. As a general rule, faster films use more granular chemistry and thus have lower resolving power (resolution) than slower films. Film shows an non-linear response to the various colors of light. Hence film can be balanced to produce more accurate colors based on the type of light to which it is exposed by buying specific film (e.g. Daylight, Tungsten) or by the use of filters.

The Focal Plane Shutter First: Slow Shutter Speeds                                                                                       Shutter closed first curtain moves Completely open second curtain moves When exposure time must be faster, then both curtains move simultaneously creating a moving slit across the film surface.

Film speed, shutter speed, and f-stop all operate on factors of two Film speed, shutter speed, and f-stop all operate on factors of two. Film speed is entered into the meter, and is a constant value. For any measured light condition the meter can calculate the correct exposure based on a specific combination of shutter speed and f-stop. Since everything is based on factors of two, there are many possible correct answers. Creativity in photography comes from using the proper combinations of correct exposure settings for the situation being photographed. Besides proper exposure, the pair of settings used can make or break a photograph. Using the correct shutter speed can freeze high speed motion or let is be expressed in controlled blur. The f-stop used controls not only exposure but also depth of field. Depth of field is used to direct attention to the areas in the photograph that you, as the photographer, wish to emphasize.

Key points of Traditional Photography: Fixed Film Speed- once the camera is loaded with film, you cannot change the speed of the film. Remember Film Speed is related to light sensitivity. Fixed Film Type-once the Film Type is selected all images will be color balanced to that type of light. You must use filters over the lens to shift the color balance. Aperture-the light intensity can be controlled by the photographer using f-stops. This provides creative control too, by selecting depth of field. Shutter Speed-the duration of exposure is selectable by the photographer, and can also be used for creative control by freezing motion or allowing it to blur. Lenses-most 35 mm cameras can be adapted with a variety of lenses from wide angle to telephoto. Exposure-exposure is calculated by using a FIXED FILM SPEED and adapting the SHUTTER SPEED and the APERTURE to balance.

Digital Cameras and Photography We'll begin with the fundamental difference between the two technologies. Digital cameras use NO FILM. Digital Cameras use a CCD cell (Charge Coupled Display) to image the photograph. The CCD is an array of individual light sensitive sensors. The sensors have an array of small built-in filters that provide for the RGB light separation. Each of the individual cells is light sensitive and their combined number represent the resolution of the array. For instance in a digital camera that claims a resolution of 1600 x 1200, there must be at least that many individual cells in the sensor array. So when an image is focused on the array each cell measures the intensity of light striking it.

A voltage is generated by the cell which is proportional to the light level. The cell converts light intensity to a voltage. 8 bit 10 bit 12 bit 256 levels 1024 levels 4096 levels The voltage is normalized in an analog to digital converter. (A/D) The A/D converter has a built-in resolution and may be 8 bits, 10 bits, or 12 bits.

More green filters are used than either red or blue as they are in the most sensitive portion of the spectrum, and impart increased sensitivity to the overall array. Across is a photograph of a real CCD cell taken through a microscope at about 10X power. Even at the magnification the individual cells cannot be differentiated. The resolution of the cell is only 512 x 480 and it comes from a real-time video camera used to capture movie video and not still images. As mentioned before each cell is light sensitive, so when an image is focused on the array each cell

The A/D then passes the scaled integer value to memory in the camera. Each integer value is placed in an associated position in the memory array. Each sensor in the ccd has a specific location that is duplicated in memory. When complete there is a one to one correspondence with the memory integers and their original ccd voltages. So now we know how the image is converted from light to interger values in camera memory. Next we need to discuss how resolution and exposure is calculated and handled in the Digital World and see how it compares with that of traditional photography.

If the film photo were created with 35 mm film, it would contain about 6000x4800 total pixels. A 5"x 4" print would thus be equal to about a 1200 dpi scan. (6000 total pixels dived by 5") Any scanning resolution used below 1200 dpi should thus be a scan of original pixel information. It would neither add nor subtract data from the resultant image. Scans at higher resolution would be capturing more data than was theoretically available on the original. If you decide that high resolution printing is your forte, then I would suggest 35 mm slides or 35 mm negatives and a good slide /film scanner. You will have better overall control and substantially higher resolution digital copies and originals to work with. Keep in mind you will have to get your film developed and then scan the originals.