I have the chance to buy a Welmy Six folding camera from a neighbor. It seems like a very well made camera. I wondered if anyone had any experience using one. Specifically I'd like to find out what the optical quality of the lens is. It has a 75mm f3.5 terionar lens. Any info on how many elements it has? I also saw a Welmy Six online with a 75mm f4.5 terionar lens. Is it much different? Thanks.