Focal length and shutter speed

[Lizziejane]

I have a question regarding some advise that was given on another thread. If focal length is 300mm then shutter speed should be about the same. I posted 2 pictures earlier today from the zoo - I was using my 300mm and the shutter speed was 640 (which is what the camera told me was the correct exposure, although they are a bit dark). Is it a "hard and fast" rule? Is it a fairly accurate guideline? Would I be better off to start with that rule, and adjust the shutter speed from there? Oh, so much to learn!

Jane

 

[KrazyPete]

I certainly think of that one as more of a guideline. It's a place to start when you have no idea where to start. Experiment! It's half the fun of learning photography.

The thing I like most about "hard and fast" rules is breaking them.

 

[0bli0]

shutter speed and focal length don't really have too much to do with each other - except to prevent motion blur from shaking the lens. ISO, shutter speed and aperture are the combination of factors that determine exposure, based upon available light.

if you were using your if you have your camera set to automatically expose a scene, 'what' you are metering can have a difference. for example the white cutie you took a photo of earlier will tend to under expose the rest of the image

 

[boBQuincy]

As the pirates said about the code, it's more like guidelines.

The slowest acceptable shutter speed depends on a lot of factors: how much sharpness is acceptable; how steady you are; are you using any kind of support; etc. Using a shutter speed at least as fast as the reciprocal of the length of the lens is only a starting place.