That is why we called it porro prism.
Porro or roof prism astronomy.
Roof binoculars are in a higher general price category than porro prism binoculars and represent a class of more powerful viewing instruments.
If you are traveling with your binoculars roof binoculars will be a better choice than porro prism binoculars because they are designed to be a lot more durable and are usually waterproof.
Roof prisms are the newer option.
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These are easy to hold for you are more compact and more expensive than porro prism binoculars.
Roof prism binoculars have lately become more popular than porro prism binoculars.
The difference between porro prism and roof prism binoculars is in the design and the respective features.
The prims are in the shape of a right angled triangle and they reflect the light rays through the binoculars so you see your image clearly.
Roof prism binocular is more streamlined as the glasses are in line with one another.
Contain 2 prisms called dach or dachkanten prism and derive their name from abbe koenig ak prism design.
Porro prism includes two right angled prisms that are facing each other.
The objective lens tube of porro prism is offset from the eyepiece.
Porro prism is made to increase the light in its path and increase the magnification so that we can get a clear bright image.
Gone is the familiar eyepiece bridge because all the workings are internal aiding with waterproofing.
Most binoculars marketed for astronomy use porro prisms named for the italian optician who invented them in the 1850s.
Roof prism units are smaller and lighter weight but have a more complicated touchy optical design which makes them more difficult and expensive to manufacture well.
There are a few reasons for this but it is mainly due to the way a roof prism still corrects the inverted image as a porro prism does but the light enters and then passes out of the prism in the same plane straight through light path meaning the designers can make a more compact and streamlined shape of binocular.
It also allows them to incorporate an enormously useful feature.
