If a shooter does not look "straight" but "diagonally" through the telescopic sight eyepiece, an aiming error occurs - the so-called parallax.
Binoculars with porro prisms are the real universal binoculars, are inexpensive and offer brighter images with higher contrast.
Lenses have the property of imaging objects upside down and laterally inverted - therefore the image must be rotated again.
Difference and comparison between Porro prisms and roof prisms The design of binoculars is always determined by the type of prism used. Porro prism in binoculars Binoculars with a porro prism design can be recognised by their relatively low height and wide design. Advantage: The greater distance between the two lenses promotes spatial vision. A graphic illustration and further details on the design of porro prisms can be found [...]