I am now searching for an Arca swiss/sinar lens board converter because I am looking forward to use my canon 5DII on the back of my hybrid and I have the 4X5 sinar to canon adapter! I do have a sinar P now (8X10 !)..my so much fuss? It's convenient to swap systems, ie the canon makes a much better proofing than a Polaroid and some of my lens are on Sinar boards and some on Arca..I still think the sturdiness and simplicity of my arca/sin makes it a very enjoyable tool !