I don't know about other people's cameras. Mine is a thing I had cobbled up, it holds together with tape and is always losing parts. All I need to set is the distance and that other thing - what do you call that other thing?

I don't know about other people's cameras. Mine is a thing I had cobbled up, it holds together with tape and is always losing parts. All I need to set is the distance and that other thing - what do you call that other thing?