The flip mirror is housed in the Tracker View Port Sleeve. This sleeve slides up and down in the view port Collar . When up, the mirror is completely out of the beam, and the target image goes to the camera. For most, if not all targets, unless you have a flip mirror to see the target, you won't be able to tell if it is even in the field of view. For CCD cameras , the target can be viewed on a computer monitor, but not live .
Most targets require several minutes of exposure to record enough of an image to be seen.
It would be like trying to find an object, and center it in the field of view with your eyes shut, being allowed to blink them open only briefly once every several minutes.