Monday, June 14, 2010

Photography Tips-How an Image is Recorded

This post will go back to the very basic idea of photography. It will essentially answer the question of "what it means to take a photograph."

Since most of my posts deal with setting such as aperture, ISO, and shutter speeds, we're going to talk about Photography through the use of a Pinhole camera, so we can ignore the fancy terminology and technique of a traditional SLR camera.

What is a pinhole camera? Well it's essentially a light tight container of some sort which has a pinhole on the opposite side of your film or photographic paper. Here is an example of a pinhole camera you can make yourself:

So essentially you poke a tiny hole in some sort of container (give the hole a cover, like a piece of tape to keep light from getting in), and you make sure the container is light tight, and you have the camera.


What about film? For a camera like the one to the left, you wouldn't buy normal 35mm film. Instead, you would go out and buy photographic paper (Ilford, Kodak) and you would cut a piece big enough to cover the opposite end of your camera.


CAREFUL! though, because this paper can NOT be opened in the light. So essentially you would go into a dark room, block all the light, and place a sheet of paper in the container on the opposite end from the pinhole, so that when you remove the piece of tape, or cover, the light is being let in towards the back of the camera, where your paper is.


What is photographic paper? Photographic paper, or film, is paper that has been coated with light sensitive chemicals. In traditional black and white photography, these chemicals are silver-halide crystals. They are light sensitive, meaning when light touches these crystals, they begin turning black. An image is created by really bright, white things reflecting more light than dark or black objects, so you get a negative image. So if you have a white cabinet with a black vase on it, the white cabinet will reflect more light into your camera, turning the halide-crystals black, creating a black cabinet, and the black vase will reflect hardly any light, and your image will have a sort of vase-outline that wasn't affected by light, leaving it white.


So we place this paper into our camera, and then we are ready to use it. Because light is what makes the image appear, the more light you have, the darker your negative (meaning when the negative is processed the BRIGHTER your positive image), the less light, the whiter the negative (or the darker the image). Some pinholes take a looong time (at least 30 seconds) to create even a faint image, so it's all about trial and error. So you'll take your camera out and remove the cover to your pinhole, and let the light start pouring into the hole, slowly creating an image on the back of your camera where your paper is.

This is essentially how a photograph is ALWAYS taken, but with an SLR you have a lens, so you have different options as to how you let the light come in, and how that makes your image look.

After you take the photo you will have to develop the paper or film in a darkroom (walgreens won't be able to do anything with photographic paper), so this is only feasible if you build a pinhole that can use 35mm film, or if you have a way of processing your own paper/film. But a pinhole camera is really just a good introduction for how an image is captured on camera.


Let's Recap:
-a pinhole camera is a light tight container that has a tiny hole on the opposite side of your photographic paper/film.
-photographic paper is light sensitive, meaning it's coated with chemicals which change shades/colors when light hits it, creating your image.
-White objects reflect the most light, altering the chemicals the most, and dark objects reflect the least light, hardly affecting the chemicals at all, creating a negative image.
-The amount of light let in to affect your image, is directly related to the amount of time you leave the "shutter open" or the cover off.
-you must place the paper in the camera in a dark room, and remove it in a dark room, and process it in a dark room, or your image will turn completely black from overstimulation to light.
-The pinhole, and the lens are similar, and time is the main factor in creating any image through any camera.


Resources:
-learn how to make a 35mm film pinhole camera:
(scroll down toward the text)
http://alspix.blog.co.uk/2005/12/31/matchbox_pinhole~428481/
-People have made their rooms pinhole cameras, lots of times!
Example:

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