One of the most important rules I learned for photography is this: don't make two things the same size.
I don't mean compositionally – I'm a huge fan of symmetry, balance, and repetition. No, I mean this in the most literal and physical way possible.
If I need to cut down some foam-core to make a reflector, I won't just divide it in half, because then when I need a card that's larger or smaller I have no options. A sixty-forty split means that one of them is bound to be right for the job, including many of the jobs that I haven't even thought of yet.
Two tripods with the same height and weight capacity aren't nearly as useful as a light one and a heavy one. Having a camera that can fit in a pocket and another that needs its own backpack – and a half-dozen different ones in between – is an essential part of my creative toolkit that just can't be replaced by having a single allegiance to a brand or lens mount.
If things are different, one of them could be perfect, and with a creative endeavour there's really no way to know ahead of time which one it will be. If everything's the same size, there's an excellent chance that nothing will be the right fit.
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