That is my concern too. I'd love the try the Rangefinder on my Samyang primes, but I shoot with a mattebox when the internal ND's on my FS7 are not strong enough. The Rangefinder's focus gear will be unusable with a mattebox, however I think if you screw on an 82mm plastic lens hood to the Rangefinder like the one below, it'll give you plenty clearance to use a follow focus and mattebox. The only issue will be using wide lenses as you willl probably get vignetting. http://www.ebay.co.uk/itm/Phot-R-82mm-PRO-Screw-On-Mount-Tele-Telephoto-Metal-Lens-Hood-Canon-Nikon-Sony-/271812381956?pt=LH_DefaultDomain_3&hash=item3f4947cd04