A brief description of what has to happen with astronomical telescopes.
The parabolic mirror reflects the light travelling down the scope back up to a secondary flat mirror that reflects that light out the side usually into an eyepiece where it is focussed.
All the mirrors have adjusters, the primary mirror has three adjusting screws that tilt the mirror to make the light cone hit the secondary at the right spot to be reflected out into the eyepiece.
These adjusters are usually at the bottom of the scope underneath the mirror cell.
Once adjusted correctly they usually only need a tiny tweak now and again.
This is called collimating the mirror.
In a binocular each tube then has to be adjusted to bring both the images into call it co-collimation so your eyes can successfully merge the two images into one.
If this co-collimation is a bit out your brain takes over and merges them for you BUT in the process giving you the most thunderous headache ever.
All these rods will allow me to tweak the co-collimation whilst looking through the eyepieces to ensure the images do allign perfectly. (I hope)
The first one as pictured is actually to move the complete mirror cell sideways as another aid in merging the images.
One mirror will move at 90' to the other mirror.
I hope this makes some sort of sense.
