1. I set my watch by the radio.
2. I set my watch by the clock.
3. I set my watch by the TV.
4. I set my camera on automatic.
5. I set my camera on flash.
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Are they all grammatical? Can we use 'according to' instead of 'by'?
They look ok to me.
And yes, "according to" is ok, as well.
I guess you are all "set" now, eh?