Download
1 / 41
410 likes | 540 Views
Art 20743 - Digital Hybrid Lecture 1. It’s all about ART and ALL of the POSSIBILITIES inherent in the medium of photography. . Before we get “technical” ...lets looks at some pictures. Joseph Nicéphore Niépce - view from his window at Gras 1826.
E N D
Art 20743 - Digital Hybrid Lecture 1
It’s all about ART and ALL of the POSSIBILITIES inherent in the medium of photography. Before we get “technical” ...lets looks at some pictures
In its simplest form a camera is a light tight box that lets light in an opening on one side so that it may strike film, paper or digital media on the other side. There are a 5 basic camera types. SLR’s, Range Finders, Twin Lens Reflex, View Cameras and Digital cameras.
There are 4 variables involved in properly exposing film or digital media. Aperture, Shutter Speed, the ISO or “Sensitivity to light”and the Amount of light at the scene are factors that need to be known and must work in concert with one another to attain proper exposure. This is true whether you are shooting film or digital pictures.
Older film cameras often had the aperture or f stop displayed on the lens The standard series of aperture numbers is: f2, f2.8, f4, f5.6, f8, f11, f16, f22 It is likely that you will also see numbers that fall between the standard series. These are not “full” f stops. On low-end digital cameras it might be difficult to find this information on the camera but it’s generally there (via various functions and menus) and it will be available through your image editing application as well through the “metadata”.
Apertures are formed by overlapping leaves of metal inside your lens that can open and close to control the volume of light entering the camera Each aperture is also known as an f Stop. Each opening lets in either 1/2 as much or twice as much light as the one before it or after it.
The aperture or f Stop also controls how much of the picture appears to be in focus. This concept is known as Depth of Field. Depth of Field is defined as the amount of the picture from foreground to background that appears to be in acceptable focus. small f# = small depth of field large f# = large depth of field Large aperture openings like f2 yield “shallow” depth of field while small aperture openings like f16 yield “large” depth of field.
Controlling how much of the picture appears to be in focus is a “creative control”. You determine what you want to draw your viewers attention to. This example shows “shallow depth of field”. A very small plane of acceptable focus runs through the boy in the middle. The boy in front and the man in the rear are clearly not in focus.
Very large depth of field allows the viewer to see everything from the foreground to the back ground in acceptable focus. This is not the way normal human vision and experience work and it may add a great deal of interest to the image. In this example the place in the image where the photographer is focusing has not changed from the shallow depth of field picture....the aperture was changed to a larger f stop number to increase the area of acceptable focus.
Depth of Field is not divided equally You should note that Depth of Field is roughly divided 1/3 in front of where you are focused and 2/3 behind where you are focused
There are two basic shutter types. Neither reveals the entire picture all at once. Leaf shutters are found in Large and Medium format cameras. They have overlapping metal leaves that open and close when the shutter button is pushed. Focal Plane shutter sit directly in front of where light is focused and are usually a curtain of metal or cloth with a slit in it that moves either up and down or side to side. Focal Plane shutter Leaf Shutter Most digital cameras don’t have a shutter at all. Rather the CCD or CMOS chip is simply turned on and off for the proscribed amount of time
Shutter Speeds on film cameras used to be found on dials that sat on top of the camera. This dial listed the standard series of shutter speeds. The Standard series of shutter speeds is: B, 1 sec., 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000 Like apertures, each shutter speed lets in either 1/2 or 2x as much light as the one before it or after it. Digital cameras do not always make it clear what shutter speeds are available unless you use a “manual” mode or an “shutter priority” mode.
The camera’s “Shutter” controls the duration of light that strikes film or digital media. Shutter speeds also control the “apparent motion” of things within the image. This is another creative control that you have access to.
Subjects that move from side to side tend to show a greater degree of blur at slower shutter speeds. This happens because the points of light forming the image will move across the film plane striking different areas of the film. This is perceived visually as movement.
Motion that comes directly toward you or away from you will show less blur even at slower shutter speeds because the light forming the image hits the film in a relatively close area of the film. “Panning” a shot means to follow it while you are shooting the picture. This renders an image that has a sharp “subject” but a blurred background.
Once you’ve determined the proper exposure via metering you are not locked into just one exposure. There are equivalent exposures and they will yield a different looking picture but it will have the same amount of overall exposure. This is true for digital photography as well
The Visible Spectrum For the purposes of the class we are primarily concerned with the visible spectrum. That is the part of the electromagnetic spectrum with wavelengths of light from 400 nanometers to 700 nanometers. These are the colors you see in the Rainbow. In the world of films there are specialty films that are sensitive to other parts of the spectrum. X-ray and Infrared are common ones.
The film you are familiar with consists of several layers. Essentially, it is a piece of plastic coated with a gelatin emulsion which has a form of silver in it. This “silver halide” emulsion is sensitive to all parts of the visible spectrum equally. Color films are constructed the same way however, they contain 3 layers of silver emulsion which will be bleached and dyed in the development process.
Film comes in a number of different formats or sizes They also come in different types and sensitivities There are advantages and disadvantages to each
Films are rated for their relative sensitivity to light. This designation is known as the ISO Number or Film Speed. The International Standards Organization is responsible for this standardized rating. Films that have low numbers are “slower” films but have finer grain Films that have higher numbers are “faster” films but have more grain Digital photography has the same system for the purposes of determining exposure. There is also an equivalent visual experience to “grain” in digital photography
To get correct exposure for film or digital cameras you must properly meter the light at the scene of the photograph This involves pointing your camera at the subject, activating the metering system and properly interpreting the results from this act. Many cameras work well with automated meter settings however, its important to understand there will be exceptions to this
Exposure for all cameras is determined by a meter calibrated for an 18% gray card This arrangement tends to works well under most conditions where the scene has a variety of tones or colors represented. This arrangement encounters difficulties when the light and tonal ranges are extreme It is important to understand this concept and how it works so that you may intelligently compensate when you run into those adverse lighting conditions
These are typically difficult lighting situations The solution is to NOT meter the extreme tones
It is critical to understand how your camera works! All Digital imaging is based on what came before it and it is important to understand the controls that you have available for creative purposes If you have a “point and shoot” digital camera you need to familiarize yourself with the following modes: Shutter Priority, Aperture Priority, Manual and Programmed Exposure.
