Wed May 12, 2021 4:45 pm
Whilst testing a behind-the-lens IRND filter option, I reset the URSA Mini 4.6K EF-Mount slightly forward using temporary thin cardboard lens mount shims to research thicknesses for metal shims to be made later.
Cardboard and paper shims with complex shapes and patterns of holes are easier to cut, punch and stack, then measure once the correct flange to focal plane distance including the indwelling filter has been restored. One need only measure the thickness of the cardboard/paper stack to choose the correct thickness of metal or plastic shim material.
Be aware that the shiny layer on some cereal packet cardboard turned out to be chemically antagonistic to the magnesium alloy and had set off a fine white powder corrosion on the surface it touched after about five weeks.