The second aspect from the Greenwich Observatory that I will go into far more detail I the development of the pinhole leading up to modern day technology.
Theory Of The Pinhole Camera
The imaging device Pinhole Camera is a hole punched through a material which is normally dark in colour, “black”. The image is the shadow of the hole, (the bright spot on a dark background.)
The larger the whole the brighter the image. This is because the amount of light being let through a larger pinhole is greater than the amount of light let through a smaller pinhole, therefore giving the image a brighter appearance. [fig 2.1]. However the draw back it that the level of detail decreases when the hole size increases. [fig 2.2].
So with a smaller pinhole although the light intensity is lower the detail level is much higher. [fig 2.3].
[fig 2.1]
As you can see if the pinhole is reduced in size there will be less light able to pass through the pinhole.
[fig2.2]
As this is the larger pinhole it is easy to see that there is a larger volume of light passing through. However because of the size there is a much larger degree of blurring. This is because the light waves passing through the pinhole have many routes to take, therefore as we see an object the edges look more blurred than usual. This is because the light reflected from the object could take many routes through the pinhole and onto the background. This means that each individual point of the image will have a large “blurring area”.
[fig 2.3]
This is the smaller pinhole and the first thing observed is that there is much less light passing through the pinhole. However what it lacks in brightness it gains in detail. Because the pinhole is far smaller than the last there are less routes for the light to travel through. Therefore the “blur area” is much smaller, giving an image of greater detail. This is why the smaller hole was preferred until the finding of the lens. [fig 2.4]. Which was used to improve the detail of the image on the larger pinholes creating a camera. Therefore there was a greater amount of light and details for the perfect image. This was when the pinhole was used by artist whom wanted to get a near photo like painting.
[fig 2.4]
Now it is obvious that the lens has pinpointed the light into the smallest points of detail. This all depends on the focal length of the lens, in general the more convex the lens the longer the focal length. So if the background is at the same length of the focal length of the lens the image will seem incredibly more detailed and brighter.
This is now the basic technology used in cameras today, but we can change the lens “size” to alter the focus. This has played a larger part in all our lives. No one has not been in a picture or seen a photo making them a very good source of data for almost any situation from the family photo book to evidence in court. With the progression of the “pinhole” since 1873 this has led on to capturing images with time (motion pictures and film). All these have only been made possible due to the discovery of the pinhole, and no one can dispute the fact that they have not been affected by the television (where all the programmes have arisen from the pinhole), which plays a larger part in our lives than ever before due to the speed of up to date news, entertainment and viewing. Economically the pinhole has led to massive income to a whole range of people from Celebs to People in Power to Gardener’s etc… Ethically the pinhole has led to a “less private life” as the latest highly technical camera and recording equipment, when used by professionals, can be very invasive and damaging to an individual’s life. An example of a pinhole camera is the Camera Obscurer in the Greenwich museum which revolves around London and displays an image on a table in a dark room.
