There have been some threads about Christmas portraits recently, however I would like to get some more input. I will be visiting family over the hoilidays and will be taking pictures in front of the tree. My basic setup is Canon T-90,85 mm lens, Sunpak 555 handle mount flash(gn 160), and lumiquest softbox on the flash, shooting either realla or nps160@125. Unlike typical portraits, I want to keep the background in focus (tree) with all of its lights and decorations. Requiring a greater dof, I am not sure of an ideal f-stop; 5.6, 8,11? Stopping down will mean more artificial light, and I am worried about over powering the lights on the tree, and also the flare from shiny decorations. I will be doing a test roll over the weekend, but this is the first time doing this type of photo, so any direction would help. I also have a wireless slave which I could mount to a vivitar flash to and use my flash meter to meter manually, instead of ttl flash, but I am not sure if I need another source of light.