The competition in the industry of binoculars is becoming more and more strained by the day. There used to be just a few manufacturers, but this is no longer the case. The purpose of this guide is to narrow down the possibilities when it comes to compact binoculars, pointing out the best choices in each of the price classes. At the beginning of this article, we explained the general features and the most common field of use of compact binoculars. Then, we divided them by price, observing the characteristics in each of the formed price classes. Finally, we listed the devices we deemed best (2019), pointing out their pros and cons.
If you have any additional questions regarding compact binoculars or any optical device from the field of sport optics, send an e-mail on email@example.com. As a team of passionate sports optics enthusiasts, we are always glad to help.
What is a compact binocular? The name couldn’t describe it any better – it is small and light, which makes it a great companion for longer tours where every surplus of weight is best avoided. It must be pointed out, however, that compact binoculars are not the smallest and lightest among binoculars as that is the privilege of pocket binoculars. Nevertheless, compact binoculars are fairly lighter than the popular 42mm objective binoculars and much lighter than the bulky binoculars designed for use in the dusk. The objective lens diameter of compact binoculars ranges from 28 to 36 mm, with 30 and 32 mm being the most commonly used values. As such, compact binoculars can easily be stored in a backpack or even a pouch.
So, why shouldn’t you choose pocket binoculars over compact ones if you want small-sized binoculars? Well, pocket binoculars might be lighter and smaller, but their eyepieces are narrower, so they are not as comfortable to use as compact binoculars. Because of this, compact binoculars are more suitable for longer observations.
There are several magnifications available with compact binoculars, the most common ones being 8x and 10x. 6x, 7x, 8.5x, 12x, and some other magnification power compact binoculars can also be purchased but are not nearly as popular. What are the main differences between 8x and 10x magnification? The lower the magnification, the wider the field of view, which means that you should go for 8x magnification if you seek a wider image. The best 8x magnification binoculars of the compact type provide around 140 m of the field of view on 1000 m, while the high-end 10x magnification compact binoculars grant approximately 120 m of the field of view on 1000 m. These binoculars are not designed to be used in the dusk because the small objective lenses cannot transmit plenty of light. Nevertheless, the 8x magnification will prove to be better in the dusky environment because it provides a greater exit pupil than the 10x magnification, meaning that more light will reach your eye. The exit pupil is the diameter of the beam of light that travels from the eyepiece to the user’s eye. It is calculated by dividing the diameter of the objective lens with magnification. In the case of 8×32 (32 ÷ 8 = 4) the exit pupil is 4 mm. The pupil of a human’s eye can dilate up to 7 mm in optimal conditions, but that value decreases as we age. If you are searching for low light binoculars, you should consider purchasing binoculars with bigger objective lenses. For a more detailed image, a bigger magnification is better – if you like seeing nature in great detail, go for 10x or even 12x magnification. The shaking of hands is more noticeable when using binoculars with a bigger magnification. You will have fewer problems maintaining a steady image with 8x magnification than with 10x magnification. For this reason, 10x magnification binoculars are sometimes mounted on a tripod, especially when used for longer periods of time. With 8x magnification, tripod mounting is rare.
Most compact binoculars feature roof prisms of the Schmidt-Pechan type. Only a few models, usually of a vintage design, contain Porro prisms – one of such is Swarovski Habicht 8×30 W. Porro prisms are known for granting a better light transmission rate than Schmidt-Pechan prisms, which is a factor to consider if you are looking for a low light binocular. With compact binoculars, though, most observations will be carried out during the day, rendering low light performance less important. We don’t know of any compact binoculars that would feature roof prisms of the Abbe-Koenig type.
Fields of use
Compact binoculars are a great choice for hikers, travellers, campers, and other nature enthusiasts. They are light enough not to be a burden on longer treks. You can carry them strapped around your neck for long periods of time thanks to their low weight, and if they are in the way, you can easily store them in the backpack thanks to their small size. Furthermore, they are a popular gift for children (and your loved ones). Children are fond of compact binoculars because they don’t weigh much and can be more comfortably used as they usually allow a setting of a short interpupillary distance (children’s faces are, naturally, smaller than those of adults).
One of the questions that we often get is whether compact binoculars can be used for hunting. We generally advise against using this type of binoculars for hunting because it often takes place in the twilight, and compact binoculars are not designed to be used in low light situations. There are some exceptions, however – mountain hunting, for example, often occurs during the day. Mountain hunts are long-lasting and burdensome, so every extra gram of weight is best avoided. On day-treks where the combination of rifle and riflescope is already heavy per se, compact binoculars are advantageous over bigger binoculars. When the sun goes down, don’t expect them to be of much use though.
Birdwatchers usually prefer the 10x or 12x magnification binoculars, as it is important for them to see as many details as possible when observing birds. Even though they are fond of 42mm objective lens binoculars, they sometimes go for the compacts as well.
If you wish to have a binocular for marine observations, go for 7x magnification or lower to avoid seasickness (if you are using it on a boat). Our recommendation is to look for a marine binocular in the corresponding category (usually of the 7×50 configuration).
Under 100 €
With compact binoculars, the quality of binoculars priced less than 100 € tends to be a little bit better than with 42mm objective lens binoculars. Their optical performance is still far from excellent, but if 100 € is your limit, compact or pocket binoculars are the way to go. Nevertheless, we highly recommend that you spend a little bit more and buy something from the 100–300 € range as you will have a much more decent optical experience.
If you are looking for a binocular that delivers acceptable optical performance, consider spending 100–300 € for it. Compact binoculars from this price class are often referred to as entry-level binoculars. A great choice for those who are into hiking, travelling, or any other kind of outdoor adventure, and are looking for something to spice up their trip. When you walk a trail, interesting animals and plants are sometimes out of your eye’s reach – why not have a binocular on you for such occasions? Let’s point out some of the features that the binoculars in this price range share. Most feature a plastic chassis combined with a single bridge. The eyecups can be set to two positions. The dioptre setting is on the right ocular. They are made in China (some exceptions, like Sightron SII Blue Sky, are made in the Philippines). Warranty periods are no longer than 2 years. We tested entry-level compact binoculars from some of the most notable optics manufacturers and came up with our own selection of best buys.
Diamondback by Vortex is one of the most popular binoculars on the market. 42mm objective lens versions are sold in the greatest numbers, but the compact versions are also quite impressive. As of 2019, the updated ‘HD’ version is available, with the most notable upgrade being the improved light transmission rate. The optical performance is great for the money, which is nothing new for Vortex – their company philosophy is based on offering as much as they can for the price. On top of that, they revolutionized the optics industry by offering unprecedented, incredible warranty terms. This is one of the few binoculars in this price class that comes with a magnesium chassis, a feature usually limited to high-end binoculars. If you are a glasses user, you will not be able to achieve the right eye relief to comfortably use these.
- Great warranty terms
- Magnesium housing
- Great optical quality for the money
- Very compact
- Difficult to use if you wear glasses
This compact binocular is something special, as it is the only one we know of that features an open-bridge design in this price class – this is rarely seen in binoculars priced less than 1000 €. The open bridge allows users to hold this compact device single-handedly. By adding this feature, manufacturers also reduce weight, which is an important factor in compact binoculars. There are three eyecup positions for an optimal eye relief setting. Sightron invests in development rather than marketing so these binoculars are not well-known but optically great for the money. These are our number one pick in terms of optics in this price class. SII Blue Sky’s main downside is the size – it is quite longer than its rivals. The strap lugs are flush with the housing.
- Open-bridge configuration
- Optically the best in class
- Strap lugs recess into the barrels
- Long for a compact binocular
Hawke is one of the market leaders in offering budget optics. With Endurance ED 8×32, they deliver great optics for the price. Both 8x and 10x magnification models provide a decent field of view. Endurance ED features a solid magnesium body, something we aren’t used to seeing in this price class. No colour fringing (chromatic aberration) is visible during observation, and it performs surprisingly well as the light begins to fade outside (even though it is of the compact type). A great buy for someone who wants to get acquainted with the world of compact binoculars. Available in black and green.
- Magnesium housing
- Low levels of chromatic aberration
- Can be comfortably used by glasses wearers
- Image is slightly yellowish
These are among the smallest and lightest compact binoculars not only in our selection but on the market itself. You can easily mistake them for pocket binoculars. The eyepieces are narrower than on other compact binoculars, so using them is not as comfortable – it does make for lower weight and smaller size, though. Optically, they are surprisingly decent. Even the field of view is quite average – the 8x magnification model offers 131 m of the field of view on 1000 m, while the 10x magnification model grants 108 m of the field of view on 1000 m. The chassis is nothing special. We like the deer logo on the bridge which makes it look a bit more expensive than it is. One of the few compact roof-prism binoculars that measure more in width than it does in length (when fully extended and with eyepieces folded in). at 169 €, these offer plenty for the money.
- Incredibly compact
- Affordable for what they offer
- Not as comfortable to use as other compact binoculars
- Build quality
Raptor is the cheapest binocular that we included in this list. Priced around 130 €, Raptor comes with Porro prisms instead of roof prisms. With this type of binoculars, it is nearly impossible to achieve 100 % waterproofness, which is why we would advise against dipping these into water or exposing them to heavy rainfall. What we like is that unlike most Porro binoculars, Raptor allows 2 eyecup position settings, which eliminates the eye relief problems for glasses wearers. As it is quite affordable, it is a great gift for a child enthusiastic about optics. Available in 8.5x and 10x magnification – both offer a decent field of view. Don’t forget – You are backed by Vortex VIP warranty should anything go wrong. Their build quality is far from exceptional, but you can’t expect much for this price.
- 2 eyecup positions, which is a rarity among Porro prism binoculars
- Great warranty terms
- Build quality
- Questionable waterproofness
Binoculars in this price class are great for beginners as well as experienced users. If you plan on using a binocular regularly and aren’t yet ready to spend a big amount of money, you shouldn’t overlook this price class as there are some great buys here. The optical quality is on a higher level than with the 100–300 € class, and so is (in most cases) the build quality. The housings are mostly made of aluminium, and you will find fewer plastic parts than on less-priced binoculars. The accessories provided with the device are of higher quality, and the scope of delivery is greater. Some binoculars are made in Japan, but most are still Chinese products. Manufacturers usually grant a 5-year warranty on these binoculars. Single bridge design prevails, and the eyecups can usually be fixed in three positions. Below, we list some binoculars we deem to be the best-performing in this price class.
One of the biggest surprises of the test. GPO is a newly formed company, but they are by no means inexperienced in the field of optics. People that run the company previously worked at other, well-known European optics-manufacturing companies. 8×42 ED was the first model of theirs that amazed us – after the test, we can say that the compact versions are just as great. We are fond of these binoculars’ build quality. The appearance gives one the impression that these are way more expensive than they are. On top of that, the eyepieces are of excellent quality. The great optical performance is the cherry on the cake. GPO is generous at providing accessories with their binoculars – it is a true rarity to receive so many quality extras at this price point. It is difficult to find any weak points considering its low cost. Our favourite binocular in this price class. As GPO is a new brand, it will take some time for them to become worthy of trust and gather followers.
- Magnesium housing
- Available in four different colours
- Build quality
- Elegant, appealing design
- Affordable for what it offers
- New brand
The 42mm version’s performance didn’t astound us during our previous in-the-field test, so we weren’t expecting much from the 32mm model. We have to admit that the compact Terra was a huge surprise for us. The image quality is decent, with the only downside being the slightly yellowish tint. The field of view is great, considering that these binoculars cost around 400 €. In terms of optics, we decided to put it on the second place, right behind the GPO. It is no secret that this device is made in China, so it can’t compete with other, more expensive Zeiss binoculars.
- Optically decent; better than the 42mm version
- Field of view
- Slightly yellowish image
Monarch 7 by Nikon is a well-known, established name on the market of binoculars. They come in polycarbonate (plastic) housing covered with rubber. Some argue that aluminium would be a better material to use, while others like it because it contributes to lower weight – this is one of the lightest binoculars in the compact category. On top of that, it is incredibly short. Eyepieces can be set to four positions. The field of view is astounding – the 8x magnification model grants 145 m of the field of view on 1000 meters, while the 10x magnification model provides 117 m. The close focus of 2 meters is great for close-range observations. Edge sharpness is not their strongest point.
- A well-known brand
- Field of view
- Four positions of the eyecups
- Lightweight and short
- Close focus of 2 m
- Build quality
- Edge Sharpness
Skyhawk 4.0 is different from other binoculars in this category but has its own strong points. The image sharp and clear in the centre. On the edges, however, chromatic aberration can be observed. These binoculars are well-built, living up to hunters’ expectations – the housing is dressed in a thick layer of rubber armouring, ensuring that the optical part is well protected. This is one of the few compact binoculars on the market that has winged eyecups – a feature some like and some don’t. It has a decent field of view and features a great solution for the installation of objective lens covers. It is quite large and heavy for a compact binocular.
- Winged eyecups (some like them, some don’t)
- Sharp centre of the image
- A reputable, renowned manufacturer
- Chromatic aberration on the edges of the field of view
- Heavy and bulky
Are you considering a purchase of a European-made binocular with a prestigious status? This is where it starts. For the premium brands, this is entry-level. For the housing, expect quality materials – in most cases, the chassis is of magnesium. Image sharpness is achieved with the help of quality glass, and images are high in contrast & rich in colours because of various lens coatings used. Eyecups can be fixed in at least 3 positions, but often there are four eyecup positions for optimal eye relief setting. Manufacturers are generous with warranty periods – expect 10 years. The single-bridge design prevails still. The devices found in this price class are made in Japan; those nearing the 1000 € price point are predominantly made in Europe. Accessories provided in the box are higher in quality than those provided with the binoculars of lower cost.
Conquest HD is a name that has been dominating this price class for quite a while now. It is no secret that these binoculars are one of the best at this price point. You can tell that these are made by Zeiss just by looking at them – the rubber covering the surface is in different shades of black. They feature a single-hinge bridge with a conspicuous yet subtle Zeiss logo on. Zeiss uses their famous T* and Lotutec coatings on the lenses, increasing light transmission and preventing the accumulation of various particles such as dust and dirt on the external parts of the lenses. This compact binocular has two main disadvantages – the first one is the truncated pupils, while the second one is weight. At 630 grams, this is one of the heaviest devices in its class. Both provide an amazing field of view. The 8x magnification model grants 140 m, while the 10x magnification model boasts 118 m of the field of view on 1000 m. It has a close focus of 1.5 m, and a fast-focus mechanism that some like and some don’t (birdwatchers are usually fond of this feature). Conquest HD can be comfortably used if you are a glasses wearer.
- One of the best binoculars if you aren’t willing to spend more than 1000 €.
- Field of view
- Close focus of 1.5 m
- Great optics for a price of around 900 €
- Heavy and bulky for a compact binocular
- Truncated pupils
As regards the build quality, Trinovid HD is our number one pick in this price class. It features Leica’s timeless design, combined with a magnesium housing and quality rubber armouring. It comes in black colour, with a red and white Leica logo on the right barrel. This is one of the biggest competitors of Zeiss Conquest HD, the two being frequently compared to one another. Trinovid’s strong points are superb build quality, elegant design, and image rich in colours and contrast. We have to point out its amazing capability of focusing objects close by – even at 1 meter of distance. The field of view is not their specialty – the 8x magnification model provides merely 124 m of the field of view on 1000 meters (10x magnification model is slightly better, providing 113 meters). If you are a glasses wearer, you can set the right eye relief on Trinovid HD to comfortably use it. It is difficult to say which one is better optically, Trinovid HD or Conquest HD – both have their strengths and weaknesses. As this is Leica’s entry-level binocular, it doesn’t feature the AquaDura coating on the external parts of the lenses. Trinovid HD is among the heaviest binoculars in its category, like Conquest HD by Zeiss.
- Elegant, timeless design
- Build quality
- Magnesium housing
- Images rich in colours and contrast
- Close focus
- Heavy for a compact binocular
- Field of view
- Leica doesn’t coat Trinovid HD’s lenses with AquaDura
Companion is Swarovski’s compact roof prism binocular. It is priced at around 1000 €, but the final price depends on the accessory pack chosen. With Companion, it is about style and image, but the optics are not to be overlooked. First, we have to point out its unique bridge system, which leaves enough place for the user to hold these binoculars with one hand. At around 500 grams, it is lighter than Leica Trinovid HD and Zeiss Conquest HD. The field of view is decent, and the image is rich in colours – which is, of course, expected from a Swarovski optical device. It is available in two colours and with three accessory packs to appease different tastes. It only offers two eyecup positions, though.
- The lightest in this price class
- Unique bridge design
- 2 eyecup positions
Meopta is one of the few that dares to compete with the great three (Swarovski, Leica, Zeiss) in this price class. Meostar B1 is a worthy competitor both optically and in terms of build quality. The construction is even more durable than that of Conquest HD, and the thick rubber armour will protect these binoculars from impacts. The dots on the rubber make for a firm grip during use. It features a central dioptre setting. Images are sharp, with a low amount of inner reflections. A great choice if you are a glasses user since you can set the appropriate eye relief. Meopta is one of the few that still grant the 30-year warranty for their products.
- Great warranty terms
- Build quality
- Excellent grip
- Heavy and bulky
The only Porro prism binocular that we included in this test. Not because roof prism binoculars are so much better, but because Porros are rare in the compact category. Habicht is a renowned name in the world of optics – Swarovski has been making these for more than 40 years, introducing only slight improvements. It features a unique shape, a result of Porro prisms inside. Interestingly, it is wider than longer. The image is amazingly sharp and crisp, and the field of view great. Even though most Porros out there aren’t waterproof, Habicht is. At 540 grams, it is of the average weight for a compact binocular. Even though we like this binocular, there are several disadvantages that it has. The first one is internal reflections, which pester the user on a bright, sunny day. The second one is the focusing wheel which is quite stiff. The eyecups are a grand problem for the glasses users – they remain in a single position, but for use with glasses, you have to push the rubber inwards so that it ‘hugs’ the eyepiece. When you do that multiple times, you are sure to damage the rubber. Other than that, Habicht proudly maintains a position among the best binoculars in this price class because of image quality and the light transmission rate.
- High light transmission rate
- Field of view
- Vintage design
- Internal reflections
- Eyecups problematic for glasses users
- Stiff focusing wheel
Are you looking for quality without compromises? Do you use binoculars daily? Do you spend plenty of time in nature and wish to inspect the beautiful surroundings up-close? If the answer to these questions is a yes, then consider purchasing the cream of the crop in the field of compact binoculars. To be honest, most binoculars in this price class are priced above 1500 € (there aren’t many binoculars priced 1000–1500 € on the market). Only the most prominent optics manufacturers have the knowledge and the audacity to construct a binocular worthy of such a price tag. These binoculars are so well-made that it is difficult to determine which one is the best – the differences are minimal. Currently, there are four competitors (Swarovski, Zeiss, Leica, Blaser), three of them old hands at optics. Blaser went straight for the high-end class with the introduction of Primus binoculars two years ago. What are some of the unifying characteristics of these binoculars? The housings are mostly made of magnesium, some feature an open bridge (even though compact binoculars are mainly of the single-bridge type because of their small size), and the eyecups can be fixed from 3 to 4 positions. The focusing mechanism is self-lubricating, ensuring that binoculars can be used at extremely low temperatures. The image is sharp not only in the centre, but also in the edges, rich in colours and high in contrast. The field of view is wide. There are many coatings on the lenses, even on the external parts (to prevent accumulation of dust, dew, and to protect against abrasion). They hold their resell value steadily, so they make for a worthy investment. Warranty is at least 10 years, and you can count on the manufacturer to repair the binoculars even after this period expires. Accessories provided in the box are of high quality (in most cases), and even the boxes in which you get the device are pleasant to look at. Occasionally, manufacturers launch a limited-edition binocular in this price class. One such is Leica Ultravid HD Plus Zagato, a wonderfully designed binocular, great for collectors and optics admirers. The prices of such binoculars are usually extremely high – most of them will be placed in a showcase and rarely be used in the field.
We have to point out that it was extremely difficult to select a #1 binocular in this category. The differences between the devices are minimal, and each has its own advantages. The battle was tense, but ultimately, we had to crown the winner – Swarovski EL. The flat field of view, a result of the Swarovision technology, is something special. When you look through them, the image ‘fills up’ your vision. It boasts a fast focus mechanism and is one of the few in the compact category that features an open bridge design, allowing use with a single hand. Optically, these binoculars are top-notch. Another feature worth mentioning is the unique strap attachment system – with other binoculars, attaching and detaching the strap is an irritating procedure, but that isn’t the case with the EL. It is available in two colours. We are not the fans of its length – EL is one of the longest compact binoculars on the market. The most expensive binoculars on this list.
- Optically great
- A flat field of view (some don’t like it)
- Open bridge construction
- A unique strap attachment system
- Too long for a compact binocular
Some in our team chose Ultravid HD Plus as the winner. The differences between this sharp-looking binocular and Swarovski EL are minimal. With Ultravid HD Plus, most pointed out its extraordinary build quality and excellent eyecups. Furthermore, it is difficult to match the colour fidelity of this great, German-made device. They are much shorter than EL and lighter as well. The housing is made of magnesium. It features a central dioptre setting. Occasionally, Leica launches limited edition binoculars under this name.
- Build quality
- Optically great (image rich in colours)
- Incredibly compact
- Occasionally, a limited edition is launched under this name
- Single-bridge design
Even though the design of these binoculars is a tad outdated, they are a worthy competitor of Leica Ultravid HD Plus and Swarovski EL in terms of optics. They have been in production since 2004, when Zeiss started using fluoride glass, and have been only slightly upgraded since then (Lotutec coating, for example, was added in 2007), hence the old-fashioned design. Zeiss uses polycarbonate for the housing, which many people dislike, saying that it is unfit for binoculars in this price class. It is lighter because of this, but far from being the lightest in the compact binoculars’ category. Build quality is nothing special, but optically, these are still among the best – and for this reason, they deserve a spot on this list. The field of view is excellent, and the images are sharp edge to edge. These are almost as short as Leica Ultravid HD Plus.
- Optically great
- Incredibly compact
- Outdated design
- Polycarbonate housing
Even though Blaser is a reputable company with a rich tradition in the field of firearms manufacturing, they are new to the world of optics. They went straight for the high-end class when they first introduced their optical devices in 2017. Is Primus worth the money? Let’s check it out. Blaser chose the elegant combination of brown and black for their first-ever binoculars. We can’t deny that they are one of the best-looking binoculars on the market. On top of that, they are really compact and lighter than most of the competition. The rest of the Primus family has Abbe-Koenig prisms integrated, but Blaser went for standard Schmidt-Pechan prisms with the compact model. This is understandable since it is not designed to be used in the dusk. These binoculars have got a particularly slow focus, which is the preferred solution for most hunters. The image is a bit yellowish, but overall, the optics are great, only slightly inferior to the three binoculars listed above.
- Slow Focus (some hunters like it)
- The lightest in this price class
- Blaser is a newcomer in the world of optics
- Not as optically perfected as the binoculars listed above
If you are an avid outdoorsman, curious for what the nature has to offer, having compact binoculars on you is a great way to enhance the experience. This guide is here to help you choose the right compact binocular based on your needs – knowing what you get for a certain price is useful. With more and more manufacturers of optics making a debut and the competition getting harsher, new compact binoculars are sure to hit the market in the near future. For this reason, we will make sure that this guide remains up to date.
Magnification is an optical parameter which enlarges/zooms the viewing image and makes the observed object seem bigger. For example, with magnification factor 10 we see objects 10 times larger, which means if an object is 0.1 m high and 100 m away we see it 1 m large. In other words, it’s the same observing the object that’s 100 meters away with a 10x binoculars as watching it with the naked eye 10 meters away. In choosing the right magnification for fixed magnification optical products, practice shows that the most useful magnifications are between 7x and 10x, where average people seem to handle optics without too much hand tremor.
Optical products with fixed magnification are designed in a way that they allow only one magnification of a viewing object. Due to a smaller number of lenses used in their construction, they are optically brighter and have a lower loss of brightness. The number of lenses contributes to its smaller size and lighter weight in comparison to optics with variable magnification. Most binoculars tend to have fixed magnification, whereas with riflescopes it’s getting rarer each year. Normally this kind of optical products are easier to use and cheaper. They also offer better optical performance, especially in terms of the light transmission rate.
Variable magnification simply means that the optical product is designed in a way where you can change the magnification of a certain area. This consequently changes the viewing angle, where higher magnification means smaller/narrower viewing angle and lower magnification means a wider viewing angle. Variable magnification adds to the versatility and general usefulness.
Lens diameter represents the second value in the product’s name/designation. For example, 10×42 optics have 42 mm diameter of the lens at the front (those that are closer to the viewing object). It is known that the bigger the lens, the more light goes through and the image we see is brighter. All of this, however, depends on the magnification and quality of a certain optical product. Although the bigger lens diameter in binoculars is better, the size adds up on the weight, making it more heavy and difficult to handle.
The most common lens diameters are 24 mm, 42 mm, 50 mm and 56 mm.
Exit pupil is a circle from which the light is being transferred to your eye through the optical product. When you hold the optics a bit far away from your eyes towards a light, exit pupil can be seen as a bright circle in the center of each eyepiece. The larger the exit pupil the more light can reach the eye and the image appears brighter. This is why the exit pupil plays an important part in the optical products in poor light conditions at dawn or dusk. Size of the exit pupil also determines how comfortable viewing through an optical product really is. An important factor is also the size of the eye box, which is a space where the eye still has an entire picture, without any tunnel vision or blurry edges. Bigger eye box means more flexibility of the eye position and therefore more comfortable viewing because the eye can move in several directions within the eye box and still obtain a full image.
The diameter of the exit pupil is calculated by dividing the lens diameter with magnification. E. g. 8×50 binoculars have an exit pupil in the diameter of 6.25 mm.
To ensure a brighter image, the eye pupil in low light conditions has to be at least as big as the exit pupil. This way there’s no loss of light and the image is as bright as possible. However, the maximum diameter of the eye pupil depends on age. At night, children’s eye pupils can widen up to 7 mm, while with aging they decrease to a maximum of 4 mm. So if the viewer’s pupils can only be open up to 4 mm, the 7 mm exit pupil cannot be fully utilized. It may contribute to a more comfortable viewing, but not to brighter image.
In daylight, when the eye pupil is open up to 3 mm, all the optics with exit pupil bigger than 3 mm are equally bright. For example, the 8×30 binoculars with 3.75 mm exit pupil are no brighter than 8×56 binoculars with 7 mm exit pupil. Those with 7 mm are however more comfortable to use since they’re less sensitive to the eye position (they have bigger eye-box).
Field of view
Field of view is an area you see when looking through the optical product. Although it primarily depends on the build of the eyepiece, it is hugely affected by magnification. If you look through two binoculars of the same model but with different magnification, you can see that the one with lower magnification factor will have a wider field of view. So when comparing binoculars, you must compare the ones with the same magnification. With binoculars, spotting scopes and other optical products it’s measured at 1000 m.
With binoculars, a field of view with more than 140 m at 1000 m distance is considered a wide angle, while with riflescopes it is with a field of view over 38 m at 100 m. Wide angle is particularly useful in bird-watching. It is also important to mention that the size and lens diameter of optical products are not indicators of their field of view – bigger housing doesn’t automatically mean wider field of view.
Field of view can be expressed in two values – degrees or meters.
One degree is 17.5 m at 1000 m / 1.75 m at 100 m.
If you divide the field of view given in meters by 17.5 you get the field of view in degrees.
If you multiply degrees with 17.5 you get the field of view at 1000m.
Apparent field of view
The apparent field of view is a value in degrees that represents the viewing angle of an image you see through the eyepiece. Two binoculars that share the same magnification, lens diameter and field of view don’t necessarily have the same apparent field of view, because it depends on the structure of the lenses inside an eyepiece. It’s simply a subjective impression of the field of view.
Apparent field of view is also depending on the eye relief distance. Shorter eye relief means wider apparent field of view. But if comparing two different binoculars with the same eye relief, the one with the larger eye lens in the eyepiece will have larger viewer field.
It can be calculated by multiplying the actual field of view with the scope’s magnification. Higher value is better as it makes the image appear wider and bigger.
Most modern binoculars are made with an element called prism which is responsible for the rotation of the image upright as the viewer sees it. Prism in binoculars also determines their size, shape, optical features and plays an important part in providing image quality of binoculars. However, prism is the most neglected factor in the process of buying binoculars. There are many types of prisms present which normally determine the purpose of a certain binoculars – whether they are for hunting, marine, bird watching etc.
Porro Prism Binoculars
Binoculars that contains Porro prism (named after Italian physic Ignazio Porro) in their optical construction were predominantly the first type of binoculars on the market. In the last couple of decades, binoculars with Roof prisms (either Schmidt-Pechan or Abbe- Köning) became more popular, due to their compactness and water-tightness. This traditional arrangement of binoculars provided by Porro-prisms makes objective lenses further apart and thus offering a higher light transmission rate. Images are not only brighter and sharper but also have a better depth of field, offering realistic 3D images and wider field of view. Many Porro prism binoculars have also focusing mechanism separated for each eye, which can be very useful in low-light situations, when observing at dusk and at dawn. Even though Porro prism binoculars are becoming rare in today’s times, this traditional arrangement makes them more affordable due to less expensive manufacturing. But wider design makes them heavier and difficult to hold in hands and they are less watertight and also less rugged, providing a less secure grip. The other disadvantage of Porro prism binoculars is also the lack of adjustable eyepieces, which in most cases leads to problems when using the binoculars with glasses.
Abbe/Koenig Roof Prism & Schmidt/Pechan Roof Prism Binoculars
Binoculars with roof-like prisms in their optical construction provide compact design due to straight-line position of eyepieces and objective lenses. They are more expensive due to complex manufacturing and are providing many advantages for more demanding users. They are less sensitive to impacts and abrasions and are incredibly impervious for water and dust entering the construction. They are usually purged with nitrogen or argon gas, which also helps to eliminate internal glass fogging. Compared to Porro prism binoculars, they are more likely to withstand extreme weather conditions. The very good ergonomic design of this straight-line construction makes them less difficult to hold in hands and eases your portability immensely. But compared to Porro prism binoculars, this construction makes light transmission less permeable and thus providing darker and less sharp images.
The main difference between both types of binoculars with Roof prism is that those with Schmidt – Pechan prisms tend to be smaller and less expensive, while those with Abbe – Köning prisms tend to have better light transmission rate and have a longer design.
Optical products have many lenses in their housing. With each lens, about 5% of the light passing through is lost. This can be solved with an application of coatings on the glass surfaces. With years the technology of coatings changed. At first, they used only one layer, where the reduction of the loss was to 2% per surface. Today they use multiple layers of coatings where there’s minimal loss of light – 0.1% per surface. The best binoculars have even 95% of the light transmitted to the eye, through all their lenses.
With the increasing transmission of the light, the coating is also important as a protectant of the optical glass and to ensure the true color fidelity, so the colors when entering are the same when exiting binoculars/riflescope. Above all, coatings also increase the image quality because all the light bouncing around on the inside can cover up detail and blur colors.
The process of applying coatings has to be precise, otherwise, it can contribute to a hazy and blurred image. They must be spread evenly and thinly to ensure the best quality. The better the coatings, the more expensive the optical product.
Lens coatings are as important as the quality of the lenses themselves. You can easily check whether your optical product has coatings – if you look at the reflection and it shows multiple colors such as purple, green or yellow the lenses are definitely coated. On the opposite, lenses with no coatings have a clear reflection without showing any colors.
There are many different ways of applying lens coatings:
- Coated: where one or more glass surfaces are coated with one thin anti-reflective layer.
- Fully coated: where all glass surfaces are coated in one thin anti-reflective layer.
- Multicoated: where one or more glass surfaces are coated in multiple layers. Light transmission is more than 75%.
- Fully multicoated: where all glass surfaces are coated in multiple layers. Light transmission is more than 85%.
- Outer surface coating: coating on the outer glass surface which protects the lens from external dew (especially in the winter), partially from dirt and other impurities. They can have different names, depending on the manufacturer (LotuTec, Swarodur, AquaDura)
Depending on the purpose of use, there are two focusing systems available in binoculars. Most common is central focusing system, which is almost without an exception present in every roof prism binoculars. The other, less occurring system, is an individual eyepiece focusing, which is most useful in marine (because of the water resistance) and extreme low light situations. Binoculars with this kind of focusing system have an advantage in setting the right focus only once for each eye, which is especially useful when viewing in the dark where it’s not necessary to set the focus again.
With central focusing, it’s often difficult to focus the image in the dark, because there is not enough light to see whether the object is sharp or not.
Binoculars with central focusing
Binoculars with central focusing have a central wheel that is able to provide perfectly sharp images. With central focus knob, you adjust the focus of both barrels at the same time, moving lenses simultaneously. When choosing between binoculars with a central focusing system it’s important to look for its design and performance. Depending on the manufacturer, some binoculars provide sturdier focusing and some very smooth focusing, which is especially suitable for dynamic situations. Focusing throw also varies from binos to binos, it takes more time for setting a proper focus with very long focusing throw, than with the ones with shorter one. When it comes to ergonomic design, most of binoculars provide a central knob with different bulges for a better grip, very convenient when wearing gloves. Since central focusing wheel doesn’t eliminate differences in both eyes, diopter on the upper side of the barrel is included.
Binoculars with individual focusing
Individual focusing system provides focusing on each eye separately. On the upper side of both barrels lie focusing rings – diopters, with the numbers for setting a proper focus by moving lenses individually. Majority of binoculars uses the central rotating knob, so this arrangement is not that frequent and most commonly found on Porro prism binoculars. Individually focusing system has many different commercial names like sports autofocus, permanent focus or simply autofocus. The main characteristic of this system is that you can set them only once and afterward the eyes focus to different distances by themselves. This can be a significant advantage in low-light situations when there is not enough light for precise focusing with a central knob. Binoculars of this type are also incredibly watertight and thus very likely to appear on the majority of marine binoculars. There are, however, some disadvantages of such focusing system compared to more conventional central focusing. Close focusing distance is usually bigger and the majority of binoculars with individual focusing does not offer adjustable eyepieces for those wearing eyeglasses.
Optical products are often filled with dry gas to prevent the condensation on the inside of the housing when exposing them to temperature extremes. If there is even a slight sign of air inside, there is a certain % of moisture present. Usually, they’re filled with either argon or nitrogen gas, which have the same effect – to prevent the moisture and internal fogging without affecting the optical properties. In addition, these gases also prevent the formation of fungus which would destroy the optics. Internal dewing was the biggest problem in older binoculars when exposed to lower temperatures because they weren’t watertight and contained air. Newer binoculars are therefore all airtight and filled with dry nitrogen or argon.
The waterproof feature is made to keep the optical products sealed and protected from water or dust. Such products are suitable for marine, hunting, hiking or in extreme humidity. Even if you’re not planning on using them in this kind of situations, it is a good feature to have in case of heavy rain or dust. Waterproof optical products are typically sealed with O-rings.
All optical products that are fogproof are also waterproof because they have to be properly sealed to keep the dry gas inside. Yet not all waterproof products are also fogproof as the air inside the product is not necessarily replaced with dry nitrogen or argon.
You should be careful not to confuse waterproof with weather-resistant as they’re designed to protect only against light rain and are not fully sealed.
Slightly better waterproofing of binoculars can also be ensured with an individual eye focusing mechanism, due to less moving parts than with the central focusing system.
Closest focus distance
The closest focus distance is an important value when watching butterflies, moths or plants at a really close distance. It represents the nearest distance where the viewing object can still be in focus. With binoculars, an excellent viewing distance is from 1.5 m below. If you’re not particularly interested in watching objects at a close range this is an irrelevant factor when choosing a new pair.
In the past, the twilight factor was an important value in determining the brightness of the optics. The manufacturers were using the same kind of technology and materials of the lenses, therefore, the optics were comparable. Nowadays, they use different types of lenses and modern coatings so the twilight factor has lost its meaning because the brightness of the optics depends more on the quality of the coatings than on the twilight factor.
Twilight factor is calculated by the square root of multiplying magnification and lens diameter.
The twilight factor of 8×42 binoculars is a square root of 336, meaning 18.33. All the binoculars with this kind of magnification and lens diameter have the same twilight factor, but not the same brightness. If you look through an old pair of binoculars made in the 1950s and a new pair with the same magnification and lens diameter you could see the difference in brightness even though they share the same twilight factor. The new pair is significantly brighter due to better lens materials and coatings.
Though manufacturers still specify the twilight factor, we recommend you to ignore it as it’s not important.
Relative brightness is a calculation of how bright the image should be when viewed through binoculars. It is presented as a square value of the exit pupil. 10×50 binoculars have an exit pupil value of 5.0 (dividing lens diameter with magnification). Square of 5.0 gives us a value of relative brightness which is 25.0. As the relative brightness value increases, we have a brighter image. On the opposite the lower the value, the darker the image.
In the past, relative brightness was an important value in determining the brightness of the optics. The manufacturers were using the same kind of technology and materials of the lenses, therefore, the optics were comparable. Nowadays, they use different types of lenses and modern coatings so the relative brightness has lost its meaning because the brightness of the optics depends more on the quality of the coatings than on the relative brightness.
Light transmission specifies an amount of light that is let through the build of the optical product. Every crossing through each lens means a certain loss of light (0.1% with best coatings, up to 5% without coatings). Higher light transmission rate is very important when using optics at dawn or twilight. Good optics normally have light transmission up to 90%, whereas top-notch ones have even 95% and more light let through.
Although the quantity of light reaching the eye depends on the size of an exit pupil, light transmission determines the transparency of the lenses, whether the image is dark and cloudy or bright and clear.
Light transmission can be increased by applying different coatings on the glass surfaces. However, it depends on the coating type and number of layers. Multi-layered coatings mean higher light transmission.
The diopter ring is present in the central focusing system on each of the barrels near the eyepiece, where you can correct the difference in the prescription of the left and right eye individually. Once you have set the right value, you can focus the image with using just the central focusing ring. If you’re wearing glasses, the diopter value should be set to 0, because the differences in your eyes are already corrected in your glasses.
To see a sharp image without wearing glasses you can easily set the diopter by looking with the bare eye, turning the ring and adjusting sharpness. So when looking with both eyes your image should appear sharp. If you have astigmatism the diopter adjustment cannot correct it – you’ll still need your glasses and diopter set to 0 to see sharp images.
is an optics enthusiast who writes articles and reviews in the field of binoculars, riflescopes, NV optics etc. Currently, he is a member of the Optics Trade team.