Hello,
so I am getting my Sinar F1 with 90mm lens soon. I will acquire a rollfilm back, so I can practice a little bit, without spending huge amounts of money on film (those 4x5 sheets are damn expensive). I will need a lens that equals the 90mm on 4x5 on either a 6x7, 6x8 or 6x9 back (haven't decided yet). I was thinking of maybe a Schneider 58mm XL? Or a Rodenstock 55mm. The 47mm XL would be too wide, or am I mistaken?