I find that the 4-way split image focusing screen gives me better focus (Focusing Screen L for AE-1 Program). However, I have 3 Canon A-1s and I like them a lot. I know that there were replacement screens for the Canon A-1 but unlike the AE-1P screens they were not user replaceable. My questions are: 1) Can the AE-1P focusing screen be installed in a Canon A-1? 2) If so, are there instructions available for user-servicing the A-1 screen?