I got some good advice about focusing cloths from this forum so I thought I'd try for some more information.
I'm just starting out in LF photography. I have a 6x9 cm field camera of unknown manufacture. If it's home made it was made by a skilled cabinet maker, but there's no manufacturers name plate . I use a Graphic "23" 120 roll film back, I get 8 images per roll. I have 2 lenses, a Zeiss Ikon Compur 105mm F4.5, and a Prontor-Press Tessar 75mm F4.5. I think both came from old folding cameras they look quite old. They are both mounted on lens plates that measure 64mm high by 60mm wide measured to the nearest mm.
Is this a standard size for a lens plate. When ever I read about lens plates they are never refered to by size but by manufacters name. Similarly the hole for the lens to fit in is never given a diameter but refered to by the shutter make and model. I'm not in the market for a new lens yet, the ones I have seem quite good. However whether or not I can buy a new lens plate or have to have one custom made will infulence the decision in the future.
Thanks for your help.