Get to know - #2 PORRO & ROOF

Get to know - #2 PORRO & ROOF

You may be considering the type of binocular to choose, one with a modern shape and intuitive construction, another with an objective lens that is powerful enough to give the impression of being awesome.

Prisms are inevitably used in optical design because we are always referencing by ourselves, the ground below our feet, and the sky above our heads. If we see an upside-down view through a small hole, our brain needs time to adjust its perception to it.

The main purpose of using prisms, whether Porro or Roof, is to correct inversions. And they use different prism sets for this purpose.

Porro

The prism system of the Porro is theoretically very effective, as the light is reflected in the prism with total reflection. In practice, however, due to differences in the quality of the prisms used (BAK4 & BAK7), the current acceptance of Porro is not as high as that of roof prisms.

Due to the angle between the two prisms, the objective lens and the eyepiece are not in a straight line, so in addition to looking bulky, there is also a difference in the sense of perspective and three-dimensionality when observing with the Porro.

However, the object lens of the Porro can be made larger, which increases the amount of light intake.

Roof

Roof prisms have actually existed for a long time, and the main reason for their popularity is that they optimise the sense of perspective and three-dimensionality when using Porro, while being able to be more portable than Porro.

However, there is a certain loss of refraction in a roof prism, and the light does not produce a total reflection on the reflective surface that enters the human eye (Schmidt-Berhan prism). Modern technology uses aluminium or silver for plating in order to reduce the light loss, which also results in a higher degree of precision in roof prisms.

Also, given the physical structure of the Roof, the objective lens is usually not as large as Porro, so the observed view will be considerably fainter.

Porro VS Roof

As with WIN and macOS, both Porro and the Roof can observe objects very well. Based on the personal usage the following aspects can be considered.

  • Portability.

For the same objective size, the Porro is usually heavier, so for simple outdoor activities, no doubt the Roof would be more suitable.

  • Budget.

Typically, Porro will be relatively inexpensive due to its simple construction, while roofs will usually be slightly more expensive. However, top of the range Porro is also very expensive.

  • Object of observation.

If there is a specific need for an observation target, please select it according to the need.

  • Conditions of observation.

Roof are generally not suitable for use in low light scenarios due to the small size of the objective lens. For performance in certain extreme conditions (heat, rain, snow, etc.), the Porro has certain advantages from a structural point of view.

  • Personal habits of use

Optics are never a product that requires attention to usage habits, so if you're someone who doesn't usually love things too much, the Paulscope will probably last longer.

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