filter pitch - RB 67 Fisheye

<p>A friend is skimming some non-dedicated 40.5mm filters to suit the RB 37mm lens. He intends to mount these into a threaded stock that can be clamped into the chuck of a lathe - however he is having problems measuring pitch of the filter thread. Presumably these are a standard metric size. Anyone know what it is??</p>

<p>Hi Neil, the RB 37mm. lens' filter thread is 0.5mm. pitch. Most filters are 0.5 or 0.75 pitch.<br /> There may be some 40.5 filters with 0.75 pitch but I don't recall having seen any - if the filter fits the lens then it's 0.5mm.<br /> Hope this helps.</p>

<p>thanks, I'll tell him.</p>