Roof Prism Binocular Collimation

The eccentric ring ajustment is more often found on roof prism bins and is extremely difficult to adjust without the correct equipment and some experience.

Roof prism binocular collimation.

These are easy to hold for you are more compact and more expensive than porro prism binoculars. In a roof prism binocular the prisms reflective surfaces resemble those of a rooftop hence the name. In the most common form of inexpensive binoculars each prism is held in place with a spring clip that tensions it against a screw that tilts the prism. The prisms are held onto a mounting plate with a metal clip.

The arrowed screws in the images are the collimation screws that pass to the outside through the housing. This can cause eyestrain headaches and a degraded user experience. The system used in binoculars consists of two prisms with at least one prism having a roof edge. Aligning the prisms the typical cause of porro prism binoculars losing collimation is being dropped or receiving a knock that shifts one of the prisms.

Normally the collimation is adjusted by screws on porro prism bins which i assume that 20x60s will be. Perfectly aligned lenses and prisms in binocular barrels produce a crisp merged image that is said to be collimated rough handling can knock binoculars out of collimation leading to fuzzy or overlapping images and possibly cat s eye shaped images in each eyepiece.