From a simple pinhole camera to the latest digital cameras, let's take a quick look at the journey.
Camera Obscura (or the pin hole camera)
Camera in Latin means a 'Vaulted Room'. Imagine carrying a whole room with you on your next trip! Well, a Camera Obscura in its initial days was not meant to be carried around and certainly not meant to capture still images. A camera obscure was simply a room (later compacted to a box) with a pin hole on one side that results in an inverted projected image of an object placed outside the pinhole on the opposite wall. I can imagine the novelty aspect of such a device but sometime in the 18th century, devices were made using angled mirrors to project the image on the top of the box or below to a sheet of paper. Such devices could be used by artists as an aid to paint still life or portraits.
The sharpness of the projected image in a camera obscura depends on the size of the pin hole. Smaller the pin hole, the sharper the image but smaller pin hole also reduces the amount of light (see aperture) resulting in a dim image. Using a lens instead of a pin hole allows for a larger aperture hence brighter image. Adding a lens created a device capable of forming a relatively bright & focussed image- the only thing missing at this time was a medium capable of capturing and retaining the images. The earliest such meduim developed by Joseph Niepce used a pewter plate coated with bitumen. Bitumen hardened on exposure to light and the unexposed bitumen would be washed away to create a crude image.
Daguerreotypes and calotypes
Developed by Louis Daguerre and Joseph Niepce, daguerreotype used a copper plate coated with silver and treated with iodine vapor. Iodine fumes reacted with silver to form light sensitive silver iodide. You couldn't pack and sell these things in the market as they had to used within an hour. After exposing them to light (for as long as 10 -20 minutes) the plates were treated with mercury and fixed with a salt solution. The end result was a beautiful black and white positive image on a copper plate. Unfortunately you couldn't ask for more copies as the plate was it. That's where Calotypes came in. Developed later by William Talbot, they used paper coated with silver iodide but treated differently to create a negative image hence making multiple positive copies possible.
Gelatin dry plate invented by Richard Maddox led to the development of cameras that could be taken outside of the studio. The dry plate was an improvement over 'wet plate' that had to be used within 10 minutes (before it dried) hence not very practical. The dry method used a glass plate coated with gelatin and silver bromide. The dry plates could be made in advanced and stored for several days. The dry plate could also be made very senstive to light resulting in an exposure time of fraction of a second compared to minutes. In earlier cameras, the photographer would remove the cap of the lens manually and keep the lens open for several minutes to explose the plate. The faster exposure time resulted in the development of a mechanical shutter - a feature of portable cameras that's still around. (Do you know that (small sensor) compact digital cameras do not have a mechanical shutter?)
Still around, though some of you kids may not have seen or used it. 'Kodak' was the first camera to use a celluloid film in 1888. It was a simple box camera with a lens and preloaded film. After about 100 exposures, the camera had to be sent back to the factory for developing and reloading. Kodak is credited for bringing photography to the masses. The very popular and inexpensive camera 'Brownie' was introduced by Kadak in 1900. Though cheaper and convinient, many professional photographers continued to use plates to create much better prints compared to film (sounds familiar to the digital and film comparison we hear these days)
35mm and Leica
You can't talk about photography without mentioning Leica. Though the photographic film and kodak cameras that used them were available in the late 1800s, they were not very popular in the professional community. In 1913, Leica developed a prototype 35mm camera (35mm refers to the width of the film) and launched a production model in 1925. Leica was a hit and it's still considered one of the most prestigious brand names in photography. The Rangefinder format led to development of many compact film cameras.
Twin lens reflex (TLR) and Single lens reflex (SLR) Cameras
Remember the camera obscura with a mirror to project image on the top? TLRs and SLRs use a similar concept to allow the photographer to look through the lens and get a sharp focussed image before lifting the mirror and recording the image on the film. Remember, in the box film cameras you had a fixed focus lens in and the rangefinders you couldn't see though the lens to make sure that the image is focussed and correctly framed. A TLR camera typically uses a medium format film (60mmx60mm frame) and uses two sets of lenses- one for focussing and the other for taking the image. The mechanism of two lenses are coupled so when you focus through one lens, the other lens move in conjuction creating the same image on the film as you see thru the focussing lens. Compared to SLRs, TLRs are mechanically simple and hence more reliable. Medium format film is also one of the reasons they were and are popular. An SLR or single lens reflex camera as the name suggests uses a single lens for focussing as well as taking the picture. SLRs have a mirror at 45d in front of the shutter that allows the image to be seen through a viewfinder set with a prism (in higher end SLRs) or another mirror. When you press the shutter release button after focussing, the mirros flips up and the shutter is activated to record the image. We'll talk about SLRs in more depth in another article.
Polaroid and the Instant Cameras
Edwin Land developed the first true instant cameras with self devoping film in 1948. The earlier cameras manufactured by polaroid used two different rolls of film but the more later versions that many of us have seen use square format integral film that produce a print without any intervention from the photographer. Polaroids were the only 'instant gratification' cameras before the digital age.
The digital revolution
Before full blown digital cameras, camera manufacturers had started integrating a lot of electronics in the cameras including through the lens light metering, auto focus and auto exposure. These are important concepts to understand and we'll talk about them in another article.
Though the concept of digitizing and storing images electronically is much older than the advent of digital cameras, the most improtant thing for thses cameras to be practical was the ability to use the digitized images. The avialability of portable color printers and the internet are the two most important reasons in my opinion that let to the enormous popularity of digital cameras inspite of the higher cost and inferior photographs (compared to film).
The earliest digital cameras were essentially still video cameras that recorded single frames to a floppy disc or a magnetic tape. The true digital cameras available now record high quality images through a CCD or a CMOS sensor to a digital memory devise (SD, CF, memory stick etc).
Digital cameras have adopted the same standards as film camera and have mimicked similar film camera formats making it easier for users to shift from film to digital. Like film cameras, digital cameras are available in two broad categories- compact and Interchangeable lens cameras. There is a third more limited category of 'digital backs' used by professionals with their existing medium format equipment.
Compact digital cameras come in all shapes and size and price range. In general they use a tiny sensor- the largest about 5% the size of a 35mm film frame in terms of area. The smaller sensor reuires lenses with small focal length which are usually also conveyed in 35mm equivalent focal length. Since there are multiple sensor sizes, the 35mm focal length provides a good basis for comparison. becasue of smaller focal length, even at full aperture, it's difficult to get a shallow depth of field which is sometimes desirable for portrait photographs. Most compact cameras also come with a zoon lens. The zoom range is usually defined as a multiple- for example a 3x zoom means that the maximum focal length of the lens is 3 times the minimum focal length. Many compact digicams have gotten rid of the optical viewfinder in favor of a live preview LCD.
Digital SLRs are more close to film SLRs in their funtionality and build. Earlier DSLRs and most professional DSLRs do not provide 'live preview' as the mirror for the optical viewfinder blocks the sensor while you frame and focus the view. Many mid and higher end consumer DSLRs however now support live preview similar to compacts and offer other bells and whistles available in consumer compact cameras. In terms of image quality, the most important difference between a DSLR and a compact is the sensor size. With and APS-C (22.2x14.8mm) or a full frame (36x24mm) sensor like in Canon 5D, a large sensor helps in getting a photograph with better dynamic range and less noise. Most DSLRs accept lenses made for the film cameras but those with less than full frame sensors have what is known as a 'crop factor'. A crop factor of 1.6 means that a 50mm SLR lens will have the same field of view as a 80mm lens when used with that DSLR (50 x 1.6).
There is a new category taking shape in higher end digital cameras which is the mirrorless interchangeable lens camera. The sensor in these cameras is larger than comapct digital cameras but smaller than SLRs. One of the standards in these cameras is the 'Four Micro Thirds' with a sensor size of 17.3x13mm. These cameras offer the advantage of interchangeable lens and better image quality but in a compact body. The most important disadvantage is the absense of through the lens optical viewfinder which is preferred by most professional photographers. A micro four thirds camera such as a panasonic GF-1 with a compact 20mm lens is a very handy street camera.
I have not covered every type of camera and photographic history in this article. Feel free to share your thoughts in the comments below.
June 29, 2011
(All photographs used under creative commons license from Wikimedia Commons)