Vortex Kaibab 18x56 HD binoculars review

In recent months, I have noticed a growing interest in binoculars with magnifications greater than 15x, but still easily portable anywhere. For this reason, I asked the official distributor of Vortex products, Origin STB , to send me a sample of the  Vortex Kaibab HD 18×56, which currently has a competitive price of 1230 euros and includes a lifetime warranty.

Vortex Kaibab 18×56 HD Review: The Ultimate Binocular for Mid- to Long-Distance Observing

As always, in this review and in the YouTube video you will find my practical impressions, as well as a detailed description of the technical characteristics, strengths and weaknesses of the product.  

Technical data declared by the parent company

• Brand: Vortex
• Model: Kaibab 18×56 HD
• Enlargement: 18x
• Objective diameter: 56mm
• Exit pupil: 3.1mm
• Pupillary extraction: 16.4mm 
• Field of view at 1000 m: 194 feet (about 64 m)
• Viewing angle: 3.7°
• Apparent field: 66.6° 
• Type of prisms: Schmidt-Pechan roof prisms
• Optical Coatings: XR Plus multi-layer, Armor Tech
• Waterproofing: Yes with Argon
• Weight: Detected 1230 g
• Warranty: For life
   

Accessories supplied

The binoculars arrive inside a “Vortex green” colored box, which contains, in addition to the binoculars, a semi-rigid black cordura bag, a quick-release adapter for connection to photographic tripod plates, an extendable cordura shoulder strap branded Vortex, a strap for the bag, a yellow cloth for cleaning the lenses and a small manual in English. The manual describes the basic operations: from adjusting the interpupillary distance to focusing, from mounting accessories to cleaning the lenses and lens caps.

Optional accessories

Vortex offers a wide range of accessories, which I invite you to discover on the official website. For these binoculars, for example, the “ Pro Binocular Adapter ” and the “ GlassPak Pro Binocular Harness ” are indicated as optimal, a quick attachment system that distributes the weight on the shoulders instead of the neck, also including an improved bag for comfortable transport and a small pocket for accessories. You can also download a PDF file with the list of all replaceable accessories, complete with serial numbers, as well as the product manual, which you will also find in paper format inside the box.

Mechanics and focusing system

I begin by confirming that this binocular from the wide Vortex range is positioned as the third in terms of quality; before it we find only the Razor model and, immediately after, the Diamondback series, thus positioning itself in a medium-high range, although it does not reach the quality of the more sophisticated models. At first glance it appears to be an imposing binocular compared to the classic 8×42: Vortex in fact recommends, without hesitation, using it on a photographic tripod. With the lens and eyepiece caps, the estimated weight is 1,280 grams, which drops to 1,230 grams without caps.

The design is classic, with a single hinge and a wide central bridge that limits any form of lateral torsion. The binoculars are well protected by a rubber armor, with an optimized coating with anti-slip textures on the sides and on the support points. At the bottom there is a small recess that facilitates the support of the thumbs and the hand. Like all Vortex products, it is waterproof and filled with argon gas instead of traditional nitrogen, since argon is less volatile.

Under the polycarbonate cap with Vortex logo is the thread for connecting the supplied adapter. Instructions for assembling the quick system are included in the package: it is necessary to fix a component that allows quick connection to the photographic plates. I invite you to consult the video for further details.

There are two attachment points for the shoulder strap on the side. The focus knob is large, measuring 26.7 x 31.9 mm , and can be used easily even when wearing winter gloves, thanks to the knurling that facilitates the grip even with sweaty or wet hands. Being a binocular designed for long-distance observations, it does not excel in focusing speed . The minimum distance I measured is 5.40 meters, and to reach infinity it is necessary to rotate the knob counterclockwise for about three and a half turns. From 10 meters to infinity, however, just under one turn is enough.

The focusing movements are precise, without any play or blockage . The diopter adjustment is entrusted to a ring on the right eyepiece equipped with a locking system: it is lifted to unlock the movements. The ring is large (48 x 10.6 mm) and has numerous reference notches for precise adjustment. On the rubber armor, immediately below the ring, there are the classic “-” and “+” signs.

Optics

Goals

Vortex declares this binocular as an “APO system”, meaning that the lenses provide a correction index that allows for excellent color rendering across the entire visual spectrum. Personally, I would define the “HD” lenses of this instrument as ED (Extra low Dispersion) since, due to its format (which provides a rather open focal ratio), the images are sharp in the center of the field with good contrast and a fair correction of chromatic aberration. The tone of the whites is slightly veered towards warm. From a construction point of view, the objectives are recessed inside the optical tube by almost 12 mm. This measure helps to protect them from scratches and, in part, from lateral light.

Eyepieces

The eyepieces have a claimed field of 194 feet at 1000 yards, or 64 meters at 1000 meters, with a viewing angle of 3.7 degrees. Using the classic formula “magnification x true field,” this translates to an apparent field of 66.6 degrees, almost 67 degrees, which makes the binoculars classed as wide angle. The eyepieces have a 47 mm diameter hood, and  at my interpupillary distance of about 66 mm, the distance between the eyepieces is 17.50 mm, allowing me to use these binoculars comfortably.

The lens hoods are equipped with a “click-stop” extraction system: the steps are accompanied by very clear and precise clicks . The protective rubber of the eyepieces is quite soft, and the internal structure of the eyepieces is made of metal, a quality detail in the price range. The declared pupil extraction is 16.4 mm. Not having professional tools, I manually checked the pupil extraction, using a silicone strip on the field lens so as not to damage it, and measuring the distance to the center of the lens with the lens hood extracted, with this technique, I estimated a pupil extraction of 15.20 mm.

I advise eyeglass wearers to test their comfort when using them, as it is possible to frame the entire field of view even with the face slightly turned away from the binoculars, but it is preferable to do some tests to obtain optimal comfort.

Prisms

The Vortex Kaibab 18×56 HD binoculars use Schmidt-Pechan roof prisms, with a 3.1 mm exit pupil that is perfectly circular. There is a slight, almost imperceptible vignetting at the edges. When framing infinity, a sharp edge (field stop) is observed, with a very thin green-yellow ring.

There are no obvious reflections near the exit pupil , although there are still some minor reflections, probably caused by the prism faces or the frame containing them, visible in the outer part of the pupil.

Anti-reflection treatment on lenses and prisms

Vortex says that these binoculars feature XR™ Plus coating, which is a fully multi-layer coating. The coating has a pleasant, low-intensity green color that performs well for the price point, although it doesn’t quite match the quality of the higher-end models. In addition to the multi-layer coating, there’s ArmorTek™ coating, an ultra-durable, scratch-resistant coating that protects the exterior lenses from scratches, oil, and dirt, while also making the exterior surfaces easy to clean.

The roof prisms are also coated with a phase correction treatment, which improves the resolution and contrast of the images. The coatings are applied using plasma technology.

Chromatic and geometric aberrations

Chromatic aberration at the center of the field

An 18×56 binocular is a decidedly advanced format, with a very open focal ratio; for this reason, without the use of high-quality fluorite crystal elements, it is almost impossible to completely eliminate residual chromatism. In fact, in critical lighting conditions on very contrasted subjects, the binocular shows a slight residual chromatism, visible especially on the contours of the most contrasted objects. In more common lighting conditions (observing landscapes, mountains, trees, etc.), the chromatism is quite contained. Considering the price range, I would define the product as ED with low dispersion glass, and not apochromatic as the price would also suggest.

Lateral chromatic aberration

Lateral chromatism is obviously visible and increases slightly as one moves from the centre of the field towards the edges, where a thin green-yellow and violet halo appears around the outlines of the main subjects.

Field curvature

The field curvature performance is excellent: the depth of field is excellent, and the daytime images are perfectly sharp all the way to the edges. When looking at long-distance details such as buildings or other landscape elements, I can confirm that the entire field of view is fully usable. This is a remarkable result, especially since some slightly higher-end products do not guarantee such a flat field all the way to the edge.

Angular distortion

This optical design has a slight pincushion distortion, visible from 70-75% of the field of view from the center . Pincushion distortion is often intentionally introduced by designers to reduce the so-called “rolling ball effect”. The perception of this effect is very subjective and I encourage beginners to understand it by reading the glossary . Some people are almost immune to it; I am one of them and have not noticed the rolling ball effect in an obvious way with these binoculars. I find that it is possible to use it pleasantly even during panning.

Other aberrations

I analyzed the performance of the Vortex Kaibab 18×56 HD using a 50 micron Geoptik artificial star and then observing the star fields. In both cases, I noted the presence of a slight astigmatism and coma, visible from about 90% of the field from the center. I would say that this is also an excellent performance.

Test with USAF chart at 35 meters

At eighteenx magnification, I was able to read line number 1, resolving both vertical and horizontal lines. Compared to higher-end products, there is a slight drop in sharpness and an increase in chromatic aberration. For comparison, the Vortex Razor HD 12×50 images are sharper and more contrasty.

I also performed the test with the Zeiss Victory 3×12 T* multiplier , even though I know that using binoculars with such a high focal length at 54x magnification can be challenging. I confirm that, despite a drop in sharpness and an increase in chromatic aberration, it was still possible to distinguish up to line number 4. This result represents an average obtained during daytime use, since I found it more difficult in the morning hours, with the lateral sun on the USAF Chart, while in the late afternoon the details were more easily distinguishable.

Test diffused light, reflections, ghost images

In daytime observation with lateral sunlight, you sometimes notice a slight presence of diffused light in the opposite part of the field of view. I then performed the classic evening test, framing a spotlight in the center of the field and moving it towards the edge: in this case, the presence of some ghost reflections was highlighted but the image was certainly readable in most of its details. This is always a very selective test where even many Top of the Range ones sin.

Practical impressions on the field

Birdwatching

An 18×56 binocular can also be useful for birdwatching. Although it does not have a suitable focus for observing birds at distances less than 5 meters, it is very good for medium-long distance observation, such as during raptor censuses from the top of observation towers or from natural observation points. In this case, the 18×56 offers excellent performance, allowing immediate recognition of birds in rapid movement, even more easily than with a 45-degree angled scope. As already mentioned, a slight chromatism can be noticed on the flight feathers when backlit, but the sharpness and resolving power of the 56 mm allow a level of detail comparable to a terrestrial observation scope of at least 65 mm at 25x. Furthermore, these binoculars are more easily transportable than a spotting scope, and the binocular vision allows for more relaxing observations, ideal for those who dedicate themselves to daily censuses: at the end of the day, those who use 18×56 binoculars will feel more rested than those who used a spotting scope.

Landscape

In landscape observation, apart from the slight chromatic aberration in strong backlight conditions, I really appreciated the apparent field of view of almost 67°. Unexpectedly, the Vortex Kaibab 18×56 HD demonstrated excellent sharpness up to the edge . For this reason, if mounted on a good topographic tripod and a video head of a decent capacity, it allows you to perceive many details. Even in this case, the visual quality is similar to that of a 65 mm – 70 mm spotting scope at magnifications between 20-25x, but binocular observation at 18x ​​allows for a more comfortable perception than using only one eye at slightly higher magnifications.

Dusk

At twilight, where I prefer an exit pupil of at least 5 mm, this 18×56 which generates a pupil of about 3 mm, is not comparable to the classic twilight 8×56 and is certainly not among my favorites.

Astronomical observation

In addition to landscape and bird watching, the Vortex Kaibab 18×56 HD has proven to be excellent for astronomical observation . It is easy to pack in a car on a hike and compact enough to fit in a backpack with a lightweight tripod, making it handy for nighttime field observations. The astronomical images it provides are superior to those of budget 15×60 models. Compared to low-cost Porro prism binoculars, the Vortex has superior optical quality, resulting in sharper star detail and more natural, pleasing color contrast. Additionally, the images remain sharp almost to the edge.

I particularly enjoyed the view of the galaxy M31 with NGC 205 in Andromeda, which occupied half the field of view, while the Double Cluster in Perseus was dotted with colorful stars against a dark sky background. The shape of the Lyra Nebula (M57) was also evident, and the Pleiades appeared as an exceptional object. M42, the Orion Nebula, also showed a fair amount of haze. The star images are almost perfect up to the edge, with stars appearing as pinheads up to about 90% from the center of the field; beyond that, however, they begin to be slightly affected by coma and astigmatism.

In moderately polluted conditions, the 18×56 format provides a wider apparent field and a darker background sky than a 12×50 or 15×50, which makes star clusters and galaxies more detailed and contrasted . Thanks to the better contrast compared to budget astronomical binoculars, even faint details such as some nebulae and galaxies can be seen with profit.  

Compared to a 15x56 binocular, the 18x56 proves more effective under moderately polluted skies, while a lower magnification binocular would be preferable for particularly dark skies. Lunar observation reveals many crater details, even if sometimes some residual chromatism is perceived on the edge of the lunar disk. Observing Saturn, it is possible to distinguish the shape of the planet and, with Jupiter, a very bright globe emerges without details that are perceived only by interposing ND filters on the eyepieces and the Galilean satellites, in addition to the presence of a light green-yellow and purple chromatic halo at the edges of the planet.

Unlike cheaper 15×60 binoculars, which are more vulnerable to mold if not stored properly, this model is fully waterproof, a useful feature for keeping the lenses free from impurities even in humid environments.

Pros and cons

Merits

Good price/performance ratio
Versatility
Robustness and waterproofing
Good edge rendering
Precise focus 
Quality accessories 
Residual chromatism containment

Defects

Requires a tripod:  With 18x magnification, a sturdy photographic tripod is essential to get sharp, stable images.
Its open focal ratio sometimes shows the presence of some chromatic aberration.

In summary

In conclusion, I think that the Vortex Kaibab 18×56 HD is a very interesting instrument, capable of replacing a 65 mm diameter spotting scope for observations not exceeding 25x magnification. Its configuration is very suitable for long-distance birdwatching and wildlife monitoring, proving useful also in hunting and wildlife control contexts. Furthermore, it is valid for landscape observations, thanks to the corrected field up to the edges. In particular, it stands out in astronomical observation, where I really liked it.

Price and warranty

The Vortex Kaibab 18×56 HD binoculars are available at a price of around 1,230 euros and come with a lifetime warranty, an added bonus for those looking for a long-lasting investment.

Thanks

I would like to thank Mauro Spozio, sales director of Origin STB , official distributor of Vortex products, for having provided the specimen which is the subject of this text and for having left me free to express my personal impressions in the field.

I reviewed on the field the Vortex Kaibab 18x56 HD Binoculars - Want to Know How It Goes?

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