I'm building a couple of 4x5 cameras and I am looking for 1. The dimensions of a "standard" square bellows for 4x5 monorail. 2. The dimensions of a bellows for a 4x5 field camera like the Linhnof. The length of the bellows is related to the focal length of the longest lens I want to use, but the opening sizes are the question. I know there may not be something like a standard size, but some representative dimensions would be helpful. Thanks in advance!