Porro mirror finder

This article or the following section is not adequately provided with supporting documents ( e.g. individual evidence ). Information without sufficient evidence could be removed soon. Please help Wikipedia by researching the information and including good evidence.

A Porro mirror viewfinder is a viewfinder system for single lens reflex cameras .

Porro mirror finders (also known colloquially as Porro prism ) are similar to pentaprism finders in their mode of operation . However, the pentaprism is replaced by a number of flat mirrors. This means that more compact and lighter cameras can be implemented; the large prism head is largely eliminated. However, the viewfinder image is usually (slightly) darker and the open construction is more sensitive to dust and more complex.

The name comes from the Italian optician and geodesist Ignazio Porro , who improved the performance of telescopes with this invention.