After quite a few months saving and a few more in correspondence with Bill Maxwell, he likes a chat, my screen finally arrived. I purchased the HI-LUX Ultra Brilliant Matte with grid, for my Shen Hao 4x5. I did some tests while mounting it on my camera and setup difficult light conditions to test the difference in screens. With the Shen Hao ground glass focussing screen I checked the brightest part of my subject through the ground glass, using a spot meter, and the exposure time was eight seconds at f8, changing to the Maxwell Screen I spotted again and it was down to a one second exposure. Unlike the Graflex Fresnel screen I had been using as a stand in, the concentric rings of the Fresnel screen can still be seen through my 10x loupe, but very faint and does not interfere with focussing. Expensive yes but the tests were done using my Super Angulon 90mm f8, which I had all but retired because focussing was hard in less then perfect lighting conditions. Now I can dust it off and put it in my kit bag.