How much of a sharpness problem are film holders? I remember reading a thread o n this board that showed considerable and significant discrepancies between wher e the film should have been and where it actually was. Is it worth investing in the more expensive Toyo holders? Are they better that the cheaper riteway etc? I suppose that the ultimate solurion is the Sinar - but that costs more than m y camera... and that's only for one of them! many thanks in advance