I too use Mamiya C330f cameras Blighty , my main interest is people photography, for child shots I find the gear I find easiest to use and get the best results with is with the L grip with trigger release, and prism finder attached to follow the action, I can hold the camera with the grip and fire the shutter with my left hand leaving my right hand free to wind on and focus , the only drawbacks with this arrangement I have found is that the prism finder is a huge lump of glass, and makes the camera so heavy it makes you're left wrist very tired after a short time, especially if I have the 135mm or 180mm lens pairs attached, but you must be prepared to "suffer for you're art"