I have two 6x7 rollfilm backs for 4x5. One is a modern-style Horseman and the other is a Graflex RH-10 (lever wind). I have not used the Horseman yet, and the last time I used the Graflex was several years ago.
When I load Ilford film into my Mamiya SLR bodies, I always need to turn it one full turn past the start marks in order to get the first shot onto the roll. With Fuji color films, I need to go 1/2 turn past the mark. It happens like this with both of my Mamiya 645 bodies (and the third one that I sold), and on my RZ. It does not happen with my Super 23 or C33 (both 1960s cameras). The cameras with inserts are the ones that are always off: the ones that wrap the film around so it is emulsion up. The ones that load the film directly into the camera emulsion down without using inserts are always right on. Ilford and Fuji are always 1/2 turn off from each other as well.
Next, since the RZ and M645 inserts are similar in design to the Graflex and Horseman inserts for 4x5, in you all's experience, do you need to make adjustments for the first frame with either Horseman or RH-10 backs?
My expected response is that something is wrong with all three of my M645s and my RZ, or with the way I am loading my film into my Mamiya SLRs.
Thank you in advance.