For handholding, tuck your elbows in, feet shoulder width apart. Effectively turn yourself into a tripod (Bipod if you're picky
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As for breathing, compose your shot then slow your breathing down, and take a few deep calm slow breaths. Then halfway through exhaling gently squeeze the trigg.., er, shutter. Don't hold your breath as this will introduce shake. Any good sniper, er, I mean photographer should tell you this
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