thanks alot , but after so much information i'm still kind of lost haha .
Go pick up a book.
To get a decently exposed picture involves 3 different factors.
1 - Film Sensitivity/Film Speed/ASA/DIN/ISO
2 - Shutter Speed
3 - Aperture
1 - Film Sensitivity
Film Sensitivity is the same as ISO on digital cameras, it represents how sensitive is your film to LIGHT!
Take a ISO/ASA (ISO or ASA) 100 film and ISO/ASA 200 for example. The 200 is more sensitive to light, and reacts to dimmer light, which means you can use the ISO/ASA 200 film in darker areas compared to a ISO/ASA 100 film.
A ISO/ASA 1600 film does not necessarily mean that it is 16x more light absorbent compared to ISO/ASA 100. ISO/ASA 1600 is 4 stops higher compared to ISO/ASA 100 films (Refer Below).
Summary
More numbers = film more reactive to light and is able to take darker stuff!
Less numbers = film is less reactive to light and is able to take brighter stuff!
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2 - Shutter speed
How long the shutter opens to let light react with the film.
Summary
Longer shutter speeds = More light goes in!
Less Shutter speed = Less light goes in!
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3 - Aperture
Aperture is how wide the "eye" is. Wider "eye", more light goes in!
Aperture is measured in ƒ-stops, less numbers = wider = more light goes in!
That means ƒ2 is significantly brighter compared to ƒ8!
Summary
Less ƒ numbers = More light goes in!
More ƒ numbers = Less light goes in!
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Summary of Everything
More light goes in = Brighter picture!
Less light goes in = Darker picture!
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Stops are ... okay whatever screw it
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The Window
Imagine your camera is like a window with shutters that open and close.
Aperture is the size of the window. If it’s bigger more light gets through and the room is brighter.
Shutter Speed is the amount of time that the shutters of the window are open. The longer you leave them open the more that comes in.
Now imagine that you’re inside the room and are wearing sunglasses (hopefully this isn’t too much of a stretch). Your eyes become desensitized to the light that comes in (it’s like a low ISO).
There are a number of ways of increasing the amount of light in the room (or at least how much it seems that there is. You could increase the time that the shutters are open (decrease shutter speed), you could increase the size of the window (increase aperture) or you could take off your sunglasses (make the ISO larger).