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Old Nov 13, 2008, 8:55 PM   #1
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Join Date: Nov 2008
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I am after some help, i am doing an assignment and have been searching for some info but everyone seems to have
different opinions that dont agree with the next answer so i thought if i come here i have a better chance of getting
correct information. I know these questions relate to film but hoping there is someone out there that can help me.

I am doing a makeup class and it includes photography.
My question is
Talk to a photographer find out about how different photographic techniques detrermine make up design and choice of
products and colours.

Black and White photography
Black and White versus Colour reproduction
Special effects such as coloured lighting or cross processing

Also this is the one i am having so much trouble trying to get correct info on:

Film speeds

I have worked out ISO rating describes how quickly the film reacts to light??? but need it explained in "normal
persons" terms like what and where these can be used

I need someone to explain to me

200 ISO
400 ISO
800 ISO

Sorry to be a pain but i cant find anything that i can understand or that doesnt contradict the next thing i read...

Thankyou to anyone who can help me

Take Care

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Old Nov 14, 2008, 6:34 AM   #2
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378

ISO speed represents how sensitive the film (or digital camera) is to light.

Each time you double the ISO speed, you can use shutter speeds twice as fast for the same exposure, given the same lighting and aperture.

You have 4 main variables to take into consideration for exposure (and I use the term "main" since there are a lot of nuances to how you measure the light (for example, your metering mode), as well as different film characteristics if shooting film, and camera settings if shooting digital for the desired tone/contrast curve within an image and more).

1. Light (typically measured as EV for Exposure Value in Photography).

2. Aperture (which works similar to the pupils in your eyes, where you can open up the aperture iris wider to let in more light, or close it down to let in less light). If you let in more light with a wider aperture, you can expose the film or sensor faster. If you let in less light with a smaller opening, it takes longer to expose the film or sensor. Note that aperture is normally expressed as f/stop, which is a ratio between the focal length of the lens and the diameter of the aperture iris. So, smaller values represent a larger iris diameter.

3. ISO speed. This is how sensitive the film or sensor is to light and is the same thing as the older ASA rating for film. The higher the ISO speed, the faster you can expose it, given the same aperture and lighting.

Higher ISO speeds are desirable in low light, so that you can use faster shutter speeds to help prevent blur from subject movement.

4. Shutter Speed (this is how long the camera's shutter stays open to expose the film or sensor).

IOW, it all boils down to how senstive the film or sensor is to light (which you control via the ISO or ASA speed of the film you use with film, or the ISO speed settings you use with digital), and how much light you need to let it see to "expose" the image which you control via the aperture opening size and shutter speed).

These exposure calculators and simulators may help your understanding:



As for Chrome Color, my guess is that you're referring to positive film (used for transparencies/color slides).

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