This weeks class was heavily based on exposure, and the tools used to achieve the correct exposure of an image.
Exposure depends on:
*ISO rating
*Subject lighting (The level of illumination)
*Subject reflectance
*Your personal preference
Because of these variables an image can either turn out over exposed, under exposed or 'correctly' exposed.
As an ISO standard we can see that a doubling of the rating = a doubling of the sensitivity
So an ISO of 400 requires half the exposure of an ISO of 200!
Setting a high ISO = Image degradation so therefore we know we should use the lowest ISO in any given situation to avoid image quality being disrupted.
We also know that digital cameras use a sensor to convert light to an electronic signal, which can then be manipulated by amplifying the signal.
We can also gather that the higher the illumination the faster the shutter speed needs to be, with a small aperture for the image to be correctly exposed, likewise when the illumination is low, the shutter speed used can be lower with a wider aperture. This sort of slow shutter and aperture width may require the use of a tri pod to avoid camera shake.
We also discussed meter reading types such as;
* AVERAGE - the entire field of view is averaged.
* EVALUATIVE - interprets scene based on data base
* CENTRE WEIGHTED - the majority of the measurement comes from the center
* SPOT - majority of light measured in a small area
Monday, March 8, 2010
Monday, February 22, 2010
F to the IRST REAL PHOTOG TECH CLASS
Clearly there are a lot of hard core technical properties that go into creating an image with a camera.
Our first real photography technology class today touched on this and was concerned mainly on basic camera controls and history with a heavy focus on exposure, shutter and aperture.
We sort of looked at camera technology in a chronological order, touching on camera history such as pin hole cameras and camera obscura (Latin words literally translation of 'dark room') We know the camera needs a few fundamentals to function:
* A Light tight body
* Lens to focus the image
* Means of capturing the image (Aka film/sensor)
* Aperture through which the light passes (A hole such as the pin hole in a pin hole camera)
* And a shutter to begin and end the exposure.
but today we moved on to look in greater detail at some of these fundamentals and the variables that can incur in them such as aperture sizes, shutter types and shutter speeds.
APERTURE: Basically a hole or opening that can be set to different sizes, hence allowing varied exposures. Basically for low light you're going to want to use a large aperture and vice versa. We were taught about Iris diaphragm (mechanism) which allow more control as it is adjustable like the iris in your eye, in comparison to apertures used in earlier cameras which were made of brass and usually had to be slotted in the camera and adjusted manually. The aperture size is associated with an F-stop which refers to a particular sized opening and an F-number which represents the F-stop. The F-numbers are kind of contradictory in a sense that the larger the number, the smaller the aperture size and the less light passed through.
We were also taught about the typical range of F-numbers with each step either doubling or halving the exposure... These were 1, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32
Shutter: The control that begins and ends the exposure, different lights require different shutter speeds. The lower the light, the longer the exposure, hence the longer the shutter needs to be opened.
There are two main types of shutters
* Focal plane and
* BTL/leaf
The shutter speed is described by numbers usually which are measured by fractions of seconds however can be measured by bigger rates than that. The larger the number the shorter the time the shutter is open for, again a little contradictory.
Again Shutter speed has a typical range of numbers which either double or halve the amount of light passed.
and last of all EXPOSURE which is the total amount of light which is captured, an image can either be over exposed or under exposed...
Basically we learnt a lot, still a long way to go but. The more I learn the more I realise I don't know!
Our first real photography technology class today touched on this and was concerned mainly on basic camera controls and history with a heavy focus on exposure, shutter and aperture.
We sort of looked at camera technology in a chronological order, touching on camera history such as pin hole cameras and camera obscura (Latin words literally translation of 'dark room') We know the camera needs a few fundamentals to function:
* A Light tight body
* Lens to focus the image
* Means of capturing the image (Aka film/sensor)
* Aperture through which the light passes (A hole such as the pin hole in a pin hole camera)
* And a shutter to begin and end the exposure.
but today we moved on to look in greater detail at some of these fundamentals and the variables that can incur in them such as aperture sizes, shutter types and shutter speeds.
APERTURE: Basically a hole or opening that can be set to different sizes, hence allowing varied exposures. Basically for low light you're going to want to use a large aperture and vice versa. We were taught about Iris diaphragm (mechanism) which allow more control as it is adjustable like the iris in your eye, in comparison to apertures used in earlier cameras which were made of brass and usually had to be slotted in the camera and adjusted manually. The aperture size is associated with an F-stop which refers to a particular sized opening and an F-number which represents the F-stop. The F-numbers are kind of contradictory in a sense that the larger the number, the smaller the aperture size and the less light passed through.
We were also taught about the typical range of F-numbers with each step either doubling or halving the exposure... These were 1, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32
Shutter: The control that begins and ends the exposure, different lights require different shutter speeds. The lower the light, the longer the exposure, hence the longer the shutter needs to be opened.
There are two main types of shutters
* Focal plane and
* BTL/leaf
The shutter speed is described by numbers usually which are measured by fractions of seconds however can be measured by bigger rates than that. The larger the number the shorter the time the shutter is open for, again a little contradictory.
Again Shutter speed has a typical range of numbers which either double or halve the amount of light passed.
and last of all EXPOSURE which is the total amount of light which is captured, an image can either be over exposed or under exposed...
Basically we learnt a lot, still a long way to go but. The more I learn the more I realise I don't know!
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