Hello, The Mamiya C330 F/S have a focus lock feature to prevent bellows from slipping out of focus. The older cameras do not have this feature. Does this mean that older cameras slip out of focus when pointed up or down? They seem like they're built so well that nothing would budge unless you wanted it to. I was thinking of getting one of the older Mamiya TLR models but wanted to know if anyone here has any "focus-slipping" problems without the focus-lock feature. Thanks.