According to DSLR camera, what’s the differences and relationships between the aperture, shutter speed and ISO?
How will them 3 effect and shape the characteristics of an image
- SumiLv 76 months agoFavorite Answer
Every exposure ever made in the history of photography going back to 1826/27 has been a combination of shutter speed, aperture and light sensitivity of the medium. ISO is a standardization of a medium's sensitivity to light. The higher the number, the more sensitive the medium. Like aperture settings, ISO ranges in "stops." Each stop indicates a doubling or halving of the light sensitivity. 200 is 2x more sensitive than 100, and 100 is 1/2 as sensitive than 200.
An exposure is simply comprised of a certain intensity of light being projected onto some medium (with some level of light sensitivity) for some amount of time. The intensity coming into the camera and eventually onto the medium is controlled by the aperture. The amount of time that the light is hitting the medium is controlled by the shutter speed. Every medium ever used has some level of sensitivity to light. As the light sensitivity changes so must one (or both) of the other two parts of the exposure triangle to ensure a proper exposure. If the ISO is lowered by one stop from, say, ISO 200 to ISO 100, then the time must be doubled or the amount of light (aperture) must be opened up by an equal amount to ensure an equivalent exposure. An "equivalent exposure" just means that while the numbers change, the overall brightness of the exposure has not. For example, say 1/500th @ f/8 using ISO 100 produces a good exposure where a middle-gray card is recorded as middle gray. If you change the shutter speed from 1/500th to 1/250th, then you will end up with a brighter card since you doubled the time of the exposure without doing anything to either the aperture or the ISO. But if you change the ISO to 50 or change the aperture to f/11, then the gray card will once again be recorded as a gray card of the exact same brightness as the image shot at 1/500th @ f/8 with ISO 100.
Shutter speed will affect the look of the image by either stopping or blurring motion.
Aperture will affect the look of the image by either increasing (higher aperture number but smaller opening) or decreasing (smaller aperture number but larger opening) the depth of field or what appears to be in focus.
ISO affects the image too. The higher the ISO the lower the color, contrast and sharpness of the image along with a higher level of noise which is relative to the size of the pixel and to a lesser degree the quality of the electronics used in the camera. Higher ISO means amplifying the signal which also must amplify any noise generated by the sensor & electronics. ISO is similar to the volume dial on a stereo. You can make quite sounds as loud as loud sounds simply by turning up the volume. Similarly you can make dark exposure at one ISO level look good simply by increasing the ISO.
- Steve PLv 76 months ago
This site / forum is fine for relatively simple answers, but you are asking to be taught a subject on which BOOKS have been written. I cannot sit here and try to explain what you are asking. First of all, this little box does not allow THAT many characters to be entered, and secondly, YOU need to take some responsibility for your own education. Stop expecting everything to be handed to you easily on a silver platter. There are TONS of tutorials and BOOKS, (you have heard of a book haven't you?), about exposure in photography. As has been said, search EXPOSURE TRIANGLE on Google and actually make an effort to learn something rather than expecting to be spoon fed all your life.
- BriaRLv 76 months ago
You will get the most detailed answer by putting "exposure triangle" into your favourite search engine.
- Long ToothLv 66 months ago
Let me get this straight: you want us to put an entire lecture on photography in a single Yahoo Answer. Those three control exposure when used as you suggest but each one also control other aspects of an image besides exposure. Aperture also controls depth of field, shutter speed also controls interactions between ISO and aperture. You will need to understand how the three legs of the 'exposure triangle' interacts.
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- Martin SLv 76 months ago
Please do your home work alone!