Beginner Question: Difference between shutter speed and exposure time?

[Keyona]

Hello;

I'm new to this forum and completely new to photography (as my signature says) but despite my research and reading I can't seem to wrap my mind around what is meant by exposure. I thought the shutter speed controlled how long the shutter was open. If so, then what is exposure? I know it's a very newbie question, but this is one point I just can't understand from the articles I've found.

I appreciate any help you could lend. Thank you!

[candleman]

shuterspeed it only one of the three ways light is controlled by the camera.
the others are ISO, and Aperture

Iso + Aperture + shutterspeed = exposure

[ravncat]

Think of exposure as - exposure =D

That probably wasn`t helpful - I mean - when you hear the word exposure, outside of photography, what might you think of? Exposing one`s self? But what are we exposed to? to experiences - cold - children. That will of course will likely lead you to Wisdom - Frostbite - lynching and jail. (I apologize to those of you that think that went too far (though I think the punishment should probably go further))

The idea is the same - Exposure - in photography - is Exposing the sensor or film - to light. We can expose it just a little bit - or alot. Shutter speed - is how long the shutter is open - how long that film is exposed to the light. If you are exposed to the cold for longer - chances of frostbite are greater.

Aperture controls how much light comes through the lens. Wide open aperture is like going out in the cold naked - lots of cold - doesn`T take as long to get frostbite. Small aperture is like wearing more clothing - we can stay in the cold alot longer before there:s a problem.

Some people think of it like a bucket and a hose - shutter speed being the time the hose is on - Aperture being how much water we let through the hose --- just replace water with light - and your bucket with a piece of film - and you:ve got it.

So - Photographic exposure = Intensity x Time.

What about this ISO nonsense? Well - that`s a bit harder to analogize. I think it is safe to say people are different - some people might suffer from frostbite much more easily than others. Such a person will require less exposure to become frostbitten. ISO is pretty much how sensitive to light, the sensor / film is. Iso 200 is twice as sensitive as Iso 100. It takes half the exposure with ISO 200 to get to the same point as ISO 100.

How does that fit in to our previous math equation? Let`s say sensitivity - and it should be there...

Photographic exposure = Intensity x Time x Sensitivity.

As one last note, ISO, Shutter speed and Aperture all have pretty important relationships to the final image. ISO is related to noise - Higher ISO more noise, smaller is less noise.

Shutter speed is related to movement - Higher shutter speeds stop movement, slow speeds show movement.

Aperture is related to depth of field (how much of the image is in focus) Smaller Aperture (larger number) more depth of field (More of the image is in focus). Bigger Aperture (Smaller number) less depth of field (Less of the image is in focus).


I hope this makes sense to you =D if It doesn`t, I will have to become more adept at explanations.

[olive]

Wow well put !!!! Thank you !!!!

[Keyona]

Thank you so very much! I finally understand.