Mary, fear not....once you really begin to understand the relationships in the exposure triangle the mystery will get out of the way rather quickly. It will all of a sudden all make perfect sense.
How about this for an analogy ...
Think of a bath, with a "correct exposure" being the bath filled almost to the top. The bigger the tap (or the hole that the water runs through), the less time you need to keep the water running to fill the bath; same with the camera - the bigger the hole (aperture), the less time it takes the light to "fill up the sensor" and the less time the shutter needs to remain open (ie "higher shutterspeed).
For ISO, just think of that as being like the pressure of the water - if the water supply to the tap is connected to a high pressure boost pump then the water will flow in faster - so you have the option of not letting it flow as long, or having it flow through a smaller hole (tap). (so for a given time the tap is open - and for a given size hole - the bath will fill quicker if the water comes from a higher-pressure source.
Make sense?
Yes. In reality though, ISO is a different one to explain in terms of baths -- it sorta/kinda changes the size of the bath - so the higher the ISO - the "smaller the bath" (or the less water/light you need to fill things up). Perhaps think of ISO as a "light multiplier" or "light boost setting" - it just effectively just amplifies the light you give it, so you need less to get the same result.
Oh. My. Word. So I totally missed the analogy.
How about... if I have the aperture set at 1.4, the shutter speed can be relatively fast because there is a lot of light going through. If the aperture is, say at 16, then the shutter speed would need to be slower so that it is open longer to allow more time for the light to go through the lens opening?
Boosting the ISO would aid in increasing the shutter speed because I probably couldn't hold the camera still enough long enough? Or in adjusting the aperture or both?
If I still am not getting... it's okay, Colin. It's not you... it's Moi. I'll go bake some cookies that will make Martha Stewart jealous.
Perfect
Yes Or if you increase the ISO you could keep the shutterspeed the same, but use a smaller hole to get a better depth of field.Boosting the ISO would aid in increasing the shutter speed because I probably couldn't hold the camera still enough long enough?
Yumm ... food!I'll go bake some cookies that will make Martha Stewart jealous.
I'm about to go get some lunch in town ... Portuguise marinated chicken (grilled), with Piri Piri sauce (fire extinguisher on stand-by) - cheese - and fries (I blame Mary!)
Well done Mary, I can see you mind getting around this now. Just take your time, enjoy learning and come back with any further questions.