There is a ULF standard that the manufacturers are now using. It is the older holders and the few that decide to make up their own that cause the problems. If a camera is made right the S & S, Lotus, ABW holders will all work. This probably will be address in the article in View Camera. If you are not sure you should have the camera back and the holders checked.
Originally Posted by BarryWilkinson
The light leak is where the dark slide goes in the holder this can be a problem on any size holder. Best to lay the dark slide or drape the dark cloth over the top when doing vertical with the light source over head.