Please answer the photographer who used the automatic film machine.

1. Generally, cameras have a rewind button (F55D, I'm not sure, there should be this button). Remember to take a few shots and then rewind the film to the tape. For example, if you shoot 10, put this film on the next shot, hang the title (if the film pair has been pulled into the film box, you need to use the film guide to pull the title out), close the camera back cover and do as you say. Pull the exposure mode to M, set the small aperture high-speed shooting 10 blank (to be on the safe side, you can shoot 1 1 blank), and the film behind you can be shot normally.

2. In order to make the viewfinder bright and convenient for framing and composition, SLR cameras adopt full aperture framing, which only reduces the aperture to the set value at the moment of taking pictures, and opens it to the maximum aperture immediately after exposure. No depth of field effect can be seen by changing the aperture size. In order to preview the depth of field effect before taking pictures, some cameras have a depth of field preview button, and the aperture is reduced to a set value after being pressed, but Nikon F55D does not have this function. So what SLR cameras see is the depth of field effect under the maximum light, which is not exactly what you see is what you get. When zooming, the influence of focal length on depth of field is directly reflected in the viewfinder (of course, at the maximum aperture).