What Are Porro Prism Binoculars? Find Out Here!

Written by 


Updated on: 

October 6, 2021

Why should you buy Porro prism binoculars and what are they?

Porro prism binoculars, or traditional binoculars, are the type that has two slightly off set triangular glass prisms that force light into a zig-zagging pattern in order to produce a clear image.

There are two main types of binoculars on the market, roof prism binoculars are Porro prism binoculars.

Even though technology and modern designs mean that these two models do not look so different anymore, there are still a few noticeable differences that separate the Porro prism types form the room prism types.

A history of Porro prism binoculars

The Porro prism binoculars as we know them today have been used for centuries having been invented by Ignazio Porro - an Italian inventor who invented the prism system in 1854.

It was this prism system that then led to the invention of Porro prism binoculars in the 1890s thanks to a German optical systems manufacturing company who repurposed the Porro prism.

These types of binoculars differ to other binoculars as the prisms within the body are purposely offset from each other.

This forces the light to zig zag through the binoculars to create a wider image within a smaller space.

Unlike other binoculars that came before, there was no need a vast amount of lenses to correct how the human eye saw the image and so the Porro binoculars turned out smaller and more compact.

What is the prism system?

We are able to see colour due to the various visible lights bouncing off of every surface we see. Lights that our eyes then see as colour.

The prism system was invented in order to dissect this coloured light and to see the colours individually through the use of a triangle piece of glass.

Such a system is possible to due the lights that then become colours to our eye travelling at different speeds. It is this variation of speed that determines the colour we see from that light.

A violet light takes the longest to reach an object where are red is the fastest and first to reach an object.

When Porro invented the Porro prism system, he used a right angled triangle and shone a light at the underside of the triangle so that the light internally reflected off of the two sloping sides.

The result was that the light bounced back at and returned at a 180 degree angle at the opposite end of where the light came from.

Porro then paired the same type of triangle with another and off set it slightly while also rotating it 90 degrees to the other triangle resulting in a double prism system.

What Porro discovered was that this method was able to take an inverted image and have it be reflected in the right way round through the use of the double prism system.

It was this exact system that was developed further and used in binoculars later on.

The advantages of Porro prism binoculars

When you are looking for a new pair of binoculars, you may be conflicted on which type of prism binocular to buy.

Usually, it is the roof prism type of binoculars that hit the higher price ranges but that does not mean that they are the best.

In fact, porro prism type of binoculars have an array of advantages:

A crisper, clearer image

Due to the fact that Porro prism binoculars have been around longer than the other most common binocular type (the roof prism binocular), there has been more time for manufactures to perfect the Porro model.

Since the invention of the Porro prism system, it has been noted how much light makes it all the way through the system without being lost along the way.

This means that the internal reflection happening within the glass prisms happens a low enough number of times that the light received on the other end is crisp and clear.

It is this crisp and clear image that you want from your binoculars.

After all, most people use binoculars in order to properly see wildlife and be able to identify them without confusion. A distinct image allows this to happen.

You will also find that it is Porro prism binoculars that offer the greater depth perception as they are able to let in more light without interruption therefore picking up on more molecular depth cues.

For the same reason, many binocular enthusiasts have notes the wider angle of view they have when using these types of binoculars further enhancing their nature observation.

Usually the cheaper choice

It is also proven through years of use that the Porro prism system works perfectly fine with just two glass prisms.

Other systems of prism systems may require more than just the two glass prisms which not only increase the chance of light being lost in the final image but also mean a bulkier product.

The more glass prisms that are used in the binoculars, the more expensive the product ends up being.

Luckily, very few brands have tried to mess with the perfect design that Perro invented when designing new Porro based binoculars.

However, this type of prism system is great to build binocular designs upon and allows manufactures to add extra features while being assured that their customers will still be able to have the distinct image that they want.

Due to the versatility of the Porro prism system, you will find that Porro type binoculars are far more common and certainly cheaper than roof type binoculars.

This is because roof prism type manufactures have to come up with solutions to overcome the loss of light during the internal reflection process.

Therefore roof prism models end up costing more to make and being more expensive to buy.

Some may argue that the extra money is worth it for the results that you get, but if you are on a budget or want to stick with traditional binoculars then Porro prism binoculars are the way to go.

The disadvantages of Porro prism binoculars

Just like with any traditional product, there are disadvantages that need to be considered when you are shopping for a new pair of binoculars and are considering buying a Porro prism pair.

Lack of coatings

One of the main disadvantages of Porro prism binoculars is also one of the many advantages.

Due to the fact that Porro prisms are able to keep the vast majority of the light that is reflected into the system, there is no need for a high reflection coating to be applied to the lenses.

While this may cut down on cost, it does also mean that there is less protection for your lenses which are the most breakable part of the whole product.

Some brands may still provide ample of protective coatings to the lenses os you might not need to worry about that but for the cheaper brands, there will still be the increased risk of scratching or marking your lenses.

Also, even though Porro prisms are very good at keeping a high percentage fo the reflected light, it would make for an even clearer image if a high reflection coating was to be applied.

Some higher priced binoculars may still include this coating but unless you have the money to spare, you may have to miss out on that advantage.

Less durable

For most people being able to save some money on a cheaper pair of binoculars is a great win. And it is for the most part.

With cheapness comes a loss of quality and the area of Porro prism binoculars that usually suffer this loss of quality is the durability aspect.

If manufacturers are able to make their product for cheaper then they will not go out fo their way to focus on other aspects like durability and will instead focus on making as much money as possible.

For that reason, most Porro prism binoculars that usually fall on the cheaper - mid priced range will not last as long as roof prism binoculars that have more thought put into them in order to be on par with the abilities of Porro prism binoculars.

That being said, you will definitely need to examine each product carefully as there are always going to exceptions to both the advantages and disadvantages of the traditional Porro prism binoculars.

Born and raised in the south coast of UK, a small town close to Cornwall, I have adventure in my blood. Ever since a young age, I have always been into the great outdoors and particularly love watching the natural wildlife. Birdwatching is what I enjoy the most, and thus my natural interest in binoculars began. I founded and run Best-Binoculars.UK a site where I talk about various aspects of and review binoculars. Hope you enjoy my ramblings :)

Read more

Related Posts

October 9, 2021
How To Clean Vortex Binoculars - Our Step By Step Guide

Our Guide To Cleaning & Maintaining Your Vortex Binoculars Contents1 Our Guide […]

October 9, 2021
How Far Can You Actually See With Binoculars? Our Guide

Whats The Farthest You Can See With Binoculars?Contents1 Whats The Farthest You […]

October 8, 2021
What Is A Diopter On Binoculars & How To Adjust Them - Our Guide

Our Guide To Adjusting The Diopter On Your Binoculars Contents1 Our Guide […]

Leave a Reply

Your email address will not be published.

Born and raised in the south coast of UK, a small town close to Cornwall, I have adventure in my blood. Ever since a young age, I have always been into the great outdoors and particularly love watching the natural wildlife. Birdwatching is what I enjoy the most, and thus my natural interest in binoculars began. I founded and run Best-Binoculars.UK a site where I talk about various aspects of and review binoculars. Hope you enjoy my ramblings :)

Best-Binoculars.UK is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.co.uk & Amazon.com.

Copyright 2021 © Best Binoculars - Reviewing & Comparing Binoculars