Whats the longest lens I can use on a bellows that is only 7 3/4 " ? I want to use a 90mm, but will a 135mm work? I realize that 135mm (5.5") doubled won't work, but what about focused at infinity? This is for landscapes and architecture, not for close up work. I suppose I can mount my 135mm on my 16' rail camera, and measure how much draw I need?