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Porro Prism

General Purpose Binoculars

      The goal of binoculars design is to provide the most natural viewing experience possible. Channeling light through a series of glass elements generates image inversion and distortion, which requires counteraction. The two most common designs are porro prism and roof prism.

Until recently, porro prism binoculars were preferred for general purposes because they delivered a brighter, sharper image than similarly priced roofs. However, roof binoculars have superior durability. They can't be knocked out of alignment because their prisms are bonded together. Whereas Porros use offset prisms, which are vulnerable to knocks.

Porro Prism

Misaligned binoculars produce a double image, which the brain struggles to convert to viable input, causing eye fatigue and headaches. Porros also have an external focus mechanism, which makes a watertight seal difficult to achieve. In contrast, roofs have an internal focus mechanism, which is relatively easy to seal against water ingress.

Purging with nitrogen gas prevents internal lens fogging by displacing air containing moisture vapor. Clearly, roof prism binoculars' waterproof and shockproof traits made them better suited to outdoor environments. Image quality was the limiting factor.

Roof Prism

Roof prisms by design, split incoming light into two beams and subsequently recombine them into a single image. Each beam is distorted by this process but to an unequal degree. Merging two beams that are out of phase degrades image resolution and contrast. Porros prisms employ a different technique, which doesn't involve merging beams.

Phase correction was game changing technology that regulated roof prisms phase shift with a special coating on each prism surface, improving image quality to match Porro binoculars. Nikon's release of the Monarch ATB was the first time a durable roof prism binocular with phase correction was available at a mid-price point.

Bird watchers are probably the most demanding consumers in terms of optical performance; the viewing experience is paramount to their satisfaction. In 2005, the Cornell Lab of Ornithology conducted an extensive binocular comparison test. The ATB 8x42 scored the highest in full size mid-price binoculars ($200-$500). They found the ATB's optical quality perfect for birding and only slightly less than premium optics, which currently cost nine times as much.

Nikon Monarch ATB Binoculars

Frankly, most people won't notice the slight difference in brightness, field of view or edge clarity and would consider the extra expenditure a waste. The ATB's optics have fully multi-coated lens, phase corrected prisms, O-ring seals and nitrogen purge. The focus is very smooth with the correct balance of speed and precision, delivering an intuitive control.

Locking twist up eye cups and 18mm eye relief supports use with eye wear. Eye relief less than 15mm will truncate the field of view when using eyeglasses. In 2010, the ATB received a slight optical upgrade; incorporating a new 'Dielectric' prism coating, to improve low light performance, giving improved brightness, resolution and contrast.

The current ATB binoculars have effectively been around since 2003; earning a reputation for durability and quality; it is still one of the most popular binoculars on the market. Nikon are so confident in the durability of the Monarch ATB; they offer a 25 year warranty; some brands only offer 2 years. The ATB is made in China. However, the factory is Nikon owned and operated, which maintains quality control.
ATB 8x42 Binos

Nikon LX-L Binoculars

Pocket Binoculars

Pocket binoculars can't match the performance of their full size brothers but satisfy specific niches like impromptu birding, stalk hunting, spectating at sporting events and sight seeing on vacation. Very few compact binoculars achieve the balance between bulk, weight, durability and image quality. Optical performance is important but the other three criteria take precedence in this particular category.

Reverse porro binoculars deliver a superior image to pocket roofs but are too bulky and delicate. Roof prism monoculars are durable and compact but can't support sustained viewing. Using a monocular for more than a few minutes will lead to eyestrain headaches. They are intended for brief observation, like spying on a shoplifter.

There several premium pocket binos available; surprisingly, only two products meet the grade, when image quality is factored in. Currently, Nikon's LX-L and Leica's Ultravid, are the only game in town. The LX-L has equal performance at almost half the price of the Ultravid, earning extra credit for value.

Don't get too misty eyed about the Germanic brands in this class; you will find they are assembled in Portugal and Romania, rather than the fatherland. Those aristocratic labels still have some cache but the truth is, Nikon binos are the top performers in every class except the premium 'alpha' binoculars.

The Nikon and Leica are dual hinged roof prism binoculars. Their compact design fits in a large shirt pocket but operation takes a little getting used to. The small lens deliver a narrow exit pupil, requiring a precise inter-pupillary distance. Setting this distance is a little slower than with standard binos, as the two hinges need to be equally adjusted.

The light weight and small focus wheel will make your hands feel clumsy at first. The Nikon's focus wheel is located on the end of the frame, requiring the pinky finger to make adjustments. Experts will advise purchasing the 8x20 model but most people are happier with the 10x25. They are slightly larger but that seems to translate to greater durability.
Nikon LX-L
Leica Ultravid


Premium Binoculars

People with wealth expect special treatment and are perfectly willing to pay through the nose to receive it. The comfort of the champagne tent at the races, corporate box at the football game or first class seating on an airliner, isn't commensurate with the premium charged.

Exclusivity is what the smart set truly crave and premium binoculars fit this niche to a tee. Their image quality is 10% better than Nikon's ATB but costs ten times as much. However, Swarovski's customer service is legendary. They will respond instantly and exceed your requests. Other European optic brands are surprising lacking in customer aftercare. If you want to feel like a king then the Swaro EL is the one to buy. He who dies with the best toys wins!
Swaro EL 8.5x42 Binos


Bino Harness

Binocular Harness:
A conventional neck strap may be convenient but it is not suitable for extended sessions or activity; the binoculars will swing like a pendulum, straining muscles and possible damaging the optics. The Vortex harness spreads the load on the shoulders, the binoculars are kept secure by the arms two anchor points and elastic that draws them close to the body.
Vortex Bino Harness
OP/TECH Connectors

Questions & Feedback.

Well, that's about it guys. I hope you found this guide useful. If you have any questions or feedback, feel free to contact me through the welcome page.

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Ian ST John.

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