What is Digital Photography?…film is replaced by an electronic image sensor
Normal film photography uses a chemical process to expose and capture images. The camera lens and body allow a controlled amount of light to come into contact with the film which is basically a sheet of plastic that has been coated with a light sensitive chemical compound. Once the film is sufficiently exposed to light an invisible image is formed. When the film is developed other chemicals are applied and the image then becomes visible forming a negative image which then can be enlarged and printed on photographic paper.
With digital photography the film is replaced with a light sensitive electronic device known as an image sensor. These sensors are made up of millions of photoelectric devices that convert light into an electrical signal. The two most common types of image sensors used in digital cameras are CCD (charge coupled device) and CMOS (complementary metal-oxide-semiconductor) sensors.The strength of the electrical signal depends upon the intensity of the light that exposes the image sensor. These electrical signals are then processed through a series of complex electronic circuits and eventually stored in some type of internal or external flash memory in a standard image file format such as a JPEG file. (JPEG = Joint Photographic Experts Group). When processed by a computer these files reproduce an image which is able to be printed on photographic paper.Just as camera film is available in different sizes so are digital image sensors. The smaller sensors found in cell phone cameras and small point and shoot cameras generally produce lower quality images than a larger sensor that would be found in a digital single lens reflex camera.
What is Digital Photography?…Understanding the Importance of Megapixels
Image sensors also differ in the number of pixels (Picture elements or the number of individual photoelectronic conductors that make up the image sensor.) Because an image sensor has millions of individual pixels the term “megapixels” is used to indicate the resolution the camera is able to capture images at. When all other things are equal a camera with a higher number of megapixels is able to capture a higher resolution image which will result in a higher quality print. The maximum print size one can make from a digital image is closely tied to the number of megapixels the cameras image sensor has.
What is Digital Photography?…Advantages of Digital Cameras Over Film Cameras
- Digital cameras allow for instant review of images. This allows the photography to have instant feedback and make any necessary adjustments to the exposure or composition right away.
- Lower overall costs. Images are easier to store and there is no need to continually buy film. Also one memory card is able to typically hold a much higher number of images compared to the typical roll of film.
- Digital cameras allow one to view images on the computer or TV and print them at home using a consumer-grade ink jet printer.
- The ability to have important information stored in the image file itself. Information can include the time, date and location of the photos as well as the camera settings and other key information can be stored in the “metadata” part of the image file.
- Digital cameras allow you to change the ISO settings from picture to picture while ISO (film speed) on a film camera depends on the role of film being used and cannot be changed from image to image within that role of film.
- No developing or processing fees involved and with the proper software there are endless numbers of ways of enhancing or manipulating the digital images. It is far easier to correct exposure problems on a digital image than it would be in the darkroom for a film image.
What is Digital Photography?…Disadvantages of Digital Cameras Over Film Cameras
- Image resolution. 35MM film has a resolution that is roughly equivalent to a 25MP full frame image sensor. While digital image sensors continue to improve and digital cameras get better every day generally speaking film still wins when it comes to image resolution and image quality.
- Film has a higher dynamic range than digital cameras. This means that it can capture a larger range of tonal quality. This is a big factor in overall image quality because it means it is harder to overexpose an image using film. Film typically can produce different shades of white which helps prevent overexposure of highlights. This means that film has the advantage when it comes to capturing shades of light especially at sunrise or sunset.
- Film is generally thought to reproduce a broader range of color than a digital image.
- Shutter lag. Digital cameras, especially the lessor expensive models are prone to have shutter lag which is the delay in time from when you press the shutter button and the time the image is captured. This lag can be long enough on some cameras that one must learn to anticipate the moment and press the shutter long enough in advance to capture the action at the right time. This can make taking shots of moving subject much more difficult. However again this is and area that has seen much improvement from some of the earlier digital cameras.
- It is difficult if not impossible to do double or multiple exposures on a digital camera. Plus digital cameras are more prone to noise on really long exposures.