Here is an Anniversary Speed Graphic and a Graflex RB Super D. Both cameras are 3-1/4x4-1/4.
What is a focal plane shutter? What is the mean difference between Pacemaker SG and Crown Graphic? I have those 2 and didn't use any of them yet [i bought one without any lens or lens board and the other with lens on lens board, so i have only 1 lens to use for both] and i don't know what i will get with over the another.
The Speed Graphics have two separate exposure systems. The first is a lens mounted in a leaf shutter at the front side of the bellows. The second is a focal plane shutter at the back of the bellows. The focal plane shutter is a piece of rubberized fabric with slits that moves in front of the film to make the exposure. To use the focal plane shutter, you need to leave the front shutter open OR to use the front shutter you need to leave the focal plane shutter open. Crown Graphics do not have the focal plane shutter. Speed Graphics can use lenses that are not mounted in a shutter.