If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
ISO speed value meaning
I understand a faster ISO means the exposure will be created faster,
thus requiring less light and enabling faster shutter speeds. What does the 50 in ISO50 mean? What does the 800 in ISO800 mean? etc. -- DD |
#2
|
|||
|
|||
ISO speed value meaning
Desert Dweller wrote in news:YVini.38$fK1.17
@newsfe12.phx: I understand a faster ISO means the exposure will be created faster, thus requiring less light and enabling faster shutter speeds. What does the 50 in ISO50 mean? What does the 800 in ISO800 mean? etc. -- DD Without getting too detailed, the ISO number is a statement of the amount of light sensitivity. It is linear (unlike f/stop) so ISO 200 means twice as much light will be recorded as ISO 100. ISO and f/stop (aperture) and shutter speed combine to give you creative control over the depth of field, stop action, etc. You may have heard of the "sunny 16" exposure rule: On a sunny day, at ISO 100, you have enough light for f/16 at 1/100 second exposure. It follows that at ISO 50 with 1/100 second, you can only achieve f/11 - half the light. If your camera (or film) is set to ISO 400 and you want f/16, you need to make your shutter speed 4x faster. More on Sunny 16 he http://en.wikipedia.org/wiki/Sunny_16_rule A general "Ohm's Law" of photographic exposure relates these three variables: ISO speed, shutter speed, and aperture. If you fix any two of these variables, the third is determined. Knowing which two to fix is the creative aspect of photography. From the tone of your questions to this NG, I would guess that you are just starting out in creative control of photographs. You might want to consider a course in photography at a local park or community college. They can teach you all the basics in short order, faster than you can learn from any book. With digital cameras, you can shoot all day long and not worry about the cost of film! have fun, Ray |
#3
|
|||
|
|||
ISO speed value meaning
Desert Dweller wrote:
I understand a faster ISO means the exposure will be created faster, thus requiring less light and enabling faster shutter speeds. What does the 50 in ISO50 mean? What does the 800 in ISO800 mean? etc. See http://en.wikipedia.org/wiki/Film_speed A google on "ISO film speed" found this as the first hit. |
#4
|
|||
|
|||
ISO speed value meaning
Ray Paseur wrote:
Desert Dweller wrote in news:YVini.38$fK1.17 @newsfe12.phx: I understand a faster ISO means the exposure will be created faster, thus requiring less light and enabling faster shutter speeds. [...] Lovely, I think I will love this group Thanks people for sharing the knowledge with us humble beginners. Regards. |
#5
|
|||
|
|||
ISO speed value meaning
Ray Paseur wrote:
Desert Dweller wrote in news:YVini.38$fK1.17 @newsfe12.phx: I understand a faster ISO means the exposure will be created faster, thus requiring less light and enabling faster shutter speeds. What does the 50 in ISO50 mean? What does the 800 in ISO800 mean? etc. -- DD Without getting too detailed, the ISO number is a statement of the amount of light sensitivity. It is linear (unlike f/stop) so ISO 200 means twice as much light will be recorded as ISO 100. Half as much light. As you go up is ISO, less light contributes to the image. That's why exposure times decrease. If you needed more light, exposures times would be longer. ISO and f/stop (aperture) and shutter speed combine to give you creative control over the depth of field, stop action, etc. You may have heard of the "sunny 16" exposure rule: On a sunny day, at ISO 100, you have enough light for f/16 at 1/100 second exposure. It follows that at ISO 50 with 1/100 second, you can only achieve f/11 - half the light. If your camera (or film) is set to ISO 400 and you want f/16, you need to make your shutter speed 4x faster. More on Sunny 16 he http://en.wikipedia.org/wiki/Sunny_16_rule A general "Ohm's Law" of photographic exposure relates these three variables: ISO speed, shutter speed, and aperture. If you fix any two of these variables, the third is determined. Knowing which two to fix is the creative aspect of photography. If you really mean aperture, then yu need another parameter: focal length. Aperture determines how much light can be collected, focal length spread it out. You probably meant f/ratio. Use of "aperture" in place of f/ratio is becoming misued too often. From the tone of your questions to this NG, I would guess that you are just starting out in creative control of photographs. You might want to consider a course in photography at a local park or community college. They can teach you all the basics in short order, faster than you can learn from any book. With digital cameras, you can shoot all day long and not worry about the cost of film! Some more info: See table 1 at: http://www.clarkvision.com/imagedeta...photons.and.qe and below tabel 2, equations 3 and 4 shows the relationship between ISO and lux. Note the constant used in the equations varies by manufacturer (and has for decades). Roger Roger |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
What's the meaning of "Ov lens"? | gunnet | Digital Photography | 0 | February 27th 05 09:03 PM |
What's the meaning of "Ov lens"? | gunnet | Digital Photography | 0 | February 27th 05 09:03 PM |
Meaning of a 2 strength close-up diopter for macro | paul | Digital SLR Cameras | 11 | January 16th 05 05:54 PM |
Meaning of Pentax Optio "Modes"? | [email protected] | Digital Photography | 10 | December 29th 04 03:08 AM |
Meaning of Tv and Av | Marcel | Digital Photography | 69 | December 16th 04 08:55 AM |