How to Choose Binoculars: We Review the OM System Olympus 10 x 42 PRO

How to Choose Binoculars: We Review the OM System Olympus 10 x 42 PRO

A good pair of binoculars are often invaluable to photographers. There are many important things to learn about buying them. Here's what led me to the OM System Olympus PRO binoculars, why they are my perfect choice, and why my old ones were a mistake.

Why My Old Binoculars Were a Mistake

My binoculars were showing their age. I bought them around 20 years ago, shortly before I moved to Tanzania. They were small, light, and easy to carry around, which I needed back then. But they had shortcomings. I know now I made the wrong decision when I bought them.

Those old Steiners were 10 x 26. That first number refers to the magnification and the second to the diameter of the objective lens. Back then, I found the 10x magnification was more than I needed for the large animals I saw in Africa, and I could often not fit the entire creature in the frame.

The second number refers to the objective lens' size. 26 mm is small, so the light transmission through them was not great; think of a camera lens with a small aperture. In the bright light of the savannah, that smaller objective lens was less of an issue. However, here in the often cloudy and dull North of England where I live now, it is. Furthermore, I am no spring chicken. Their low light-gathering capacity meant that, although I see things 10 times bigger, the image was dull and lacking detail, and I gained little from using them. Everyone's vision gradually deteriorates with age, and a dark image isn't what I need.

Consequently, although they fit in my pocket, I rarely take them anywhere. If only I knew then what I know now, I would have invested in something better.

What I Needed From Binoculars

Since then, my appreciation of how bigger and better-quality lenses make a huge difference in image quality has grown. If I photograph using the M.Zuiko PRO lenses I own, I can see a sizeable increase in sharpness compared to standard lenses. I concluded it must be the same with binoculars.

So, I wrote down my requirements based on avoiding the mistakes I had made in the past, plus my needs now. Firstly, as I said, the image had to be as sharp as possible to pick out the fine detail of the subject I was watching. I also want greater light-gathering capacity, showing those details even in the shadows. Additionally, I needed sufficient magnification; most wildlife here in the UK is not as big as the animals I saw in Africa. I also needed them to be robust and comfortable to use. Finally, I wanted them to be robust but light and ergonomic.

My Choice of Binoculars

I know that my OM System camera lenses are known for being hypodermic needle-sharp. A search of many different review websites also rated that brand's binoculars as exceptionally good. Furthermore, I know it is a brand I can trust. But, even so, I wanted to put them to the test to be sure.

OM System produces three grades of binoculars – Compact, Standard, and PRO – still sold with the Olympus branding. I went for the PRO version mainly for its increased clarity of image, durability, and because they are waterproof. So, before buying, I trialed a pair of mid-sized OM System Olympus 10 X 42 PRO binoculars.

My First Impressions of the Binoculars

On unpacking them, I found the binoculars were pleasant to hold. The rubberized grip was warm to the touch. The focusing ring was large and easy to reach with my forefinger and thumb.

Importantly, its focusing action was smooth, with just the right amount of resistance to focus quickly and accurately. Many pairs I tried over the years are too tight and jerk when you start to turn them, and others are too loose. But not these. They fit in the Goldilocks zone.

The hinge between the two barrels is tighter, which is excellent. Once set to the correct distance between my eyes, they stayed there.

They weighed just 665 g (1.46 lb).

It took a few moments to set up the binoculars. The eyecups unwind and extend; you don't do this if you are wearing glasses. Then, you focus on a subject using your left eye only. Once that is sharp, swap over your eyes and use the diopter adjustment on the right eye to tweak the focus. It's worth spending a little while to get this right.

Putting the Binoculars to Use

On my outing with the binoculars at a bird conservation workshop, I could spot and clearly identify small shorebirds, like avocet and redshank, 260 yards (approximately 235 meters) from where I was standing. They also have a close, 5-foot (about 1.5 meters) minimum focussing distance, making them ideal for observing butterflies in fine detail.

The bokeh was nice and creamy looking. Even looking at a subject a reasonable distance from me, the background smoothly blurred, thus isolating the subject from its environment.

If you click on this image, you will get a rough approximation of the depth of field and how much the bokeh is blurred through 10 x 42 binoculars. 

Just as you find with long camera lenses, that shallow depth of field gave great separation between the subject and the out-of-focus foreground and background. The result is a hyper three-dimensional look, not dissimilar from watching a 3D movie in an IMAX cinema. I actually said, "Wow!" out loud when I first focused on a bird flying over the estuary.

Image Quality of the OM System Olympus 10 x 42 PRO Binoculars

My previous binoculars, convenient though they were, lacked good light-gathering capacity because of the small objective lens. In comparison, the 42mm lenses on the Olympus binoculars are far larger. Consequently, the image is much brighter. As one would expect with binoculars in this class, the image was superb.

How the optics are put together means that the maximum possible light would reach my eye. The nine elements in three groups, including the extra-low dispersion (ED) objective lens, the phase-correcting and dielectric coatings on the BAK4 prisms, and the anti-reflection fully multi-coated optics gave me clean, sharp, high contrast views of my subjects.

The colors were accurate, and I could detect no distortion, ghosting, or fringing.

That high performance is partly due to having the same Olympus' ZERO coating found on their camera lenses to reduce flaring and ghosting. In fact, these binoculars transmit over 95% of light in the visible spectrum (400 to 700 nm), better than the equivalent  Swarovski EL 10 x 42 E B binoculars that cost nearly five times as much.

Understanding Magnification

This is a gross over-simplification, but 10 times magnification is approximately what you get when you look through a 440-500mm camera lens. But it is far more complex than that because you are not projecting the image onto a sensor. There is also a far wider field of view with binoculars.

Choosing the correct magnification for you is essential. If you can handhold those focal lengths on a camera without image stabilization, you should be able to handhold 10x binoculars. If you struggle to do that, or cannot keep a moving subject within the frame, then slightly less powerful binoculars may be a better fit for you.

When I have been sailing at sea, with the boat's movement, 8x magnification is far easier to manage. I bought some 16 x 50 mm binoculars in my teens, believing that more magnification was always better. I was wrong. They were difficult to hold on to a subject and nearly impossible to use on my boat. I rarely sail now, so that wasn't a consideration.

Lower-magnification binoculars can be brighter, too. Thinking of it in camera lens terms, it's a shorter lens with the same aperture diameter, so a lower f/stop. Nevertheless, I was confident that these binoculars would be fine. They were.

Whereas those antelope and elephants in the Tarangire National Park were huge and sometimes in very close proximity, 10 times magnification was overkill. But most wildlife here is tiny and measured in inches instead of yards. Plus, birds and small mammals don't want to get too close, and neither do I want to get too close and scare them. I concluded that 10x magnification was the best choice for me. But I was nearly persuaded by the 8x model.

A Note About the Angle of View

There are two angle measurements quoted for binoculars that are related to magnification. The first is the real field of view. This is the angle of view you get from the binoculars. With these 10 x 42s, it is 6.2°, while with the 8 x 42 model, it's 7.2°.

Approximately 6.2 degrees. Looking through the binocular, the island will be 10 times larger and the field of view falling within the red lines.

Then, there is the apparent field of view, a more useful reference. If you imagine walking forward until an object in front of you is 10 times larger, the angle across it would be more obtuse. That's the apparent field of view. This is 56.9° with 10 x 42 binoculars and 55.3° with 8 x 42s.

The green line represents the apparent field of view. That is how the image appears through the binoculars. It is as if you were standing 10 times closer. The angle is more obtuse.

Build Quality and Ergonomics

Robustness was also an important consideration. I often clamber over rocks on rugged beaches splattered with sea spray. I wanted something that wouldn't fall apart with the first knock or have water ingress into the optics.

I always emphasize how important ergonomics is when choosing a camera. Nothing is worse than using something unwieldy and giving you a neck ache. The same applies to binoculars. I wanted a light pair that was a good size for my hands with a wide comfortable strap.

Large, full-sized binoculars are available on the market, but the ergonomic disadvantages of these big, heavy ones were enough to put me off considering those.

The binoculars are rated as waterproof and can be submerged up to a meter for five minutes. The lens coatings are water and oil resistant, so they shed the rain very quickly; it was raining when I first tested them. Their nitrogen-filled body prevents fogging and corrosion.

My tests for this article were well timed for you, but I got soaked. Like with the weather-sealed OM System cameras, getting caught in a rain shower isn't a problem for these waterproof binoculars.

What I Liked and What Could Be Improved

These are high-quality, professional instruments. The huge difference I noticed using these binoculars compared to anything else I had used before is their brightness. I tried this pair and my old binoculars side-by-side and watched the eider and cormorants on the water and flying. With the Olympus binoculars, I could see details in the shadows that were not visible with the smaller, older ones. Furthermore, those old Steiners seemed to put a slightly muddy cast, whereas the Olympus ones were crystal clear.

Obviously, I can't show you the actual difference. However, the picture below roughly approximates how the subjects looked to me through the Olympus binoculars on the right compared with the old Steiners on the left. With the old binoculars, I could barely differentiate the eider's eye from its feathers.

The focussing action was smooth and fast. I could track flying birds and quickly swap between foreground and background subjects. The large, ridged, and rubberized focusing wheel was easily adjusted, even when wearing gloves. Additionally, the slightly sculpted features and the texture of the barrel made them easy to grip. I liked that they were light and, even with their low profile, were comfortable to use with my large hands.

The strap is wide and slightly elastic. I was glad to see that the loops on the body were the same width as a camera strap, so I could fit an even wider strap if necessary. I could also use the binoculars at the same time as my camera on its shoulder strap.

Unlike some binoculars, these binoculars are supplied with lens caps. The objective lens caps can be removed completely, but they are designed to be secured to the body with the caps' integral rubber loops. Similarly, the eyepiece caps are joined together and tethered to the strap, so you don't lose them. The binoculars also come supplied with a padded nylon storage case with a belt loop.

I struggled to find anything amiss with these. I enjoy using high-quality precision tools, and this is what they are.

There should be an optional tripod adaptor available for them. However, at the time of writing, I could not find one for sale. However, I have no need for that. There are other generic adaptors on the market, though.

Some binoculars have image stabilization. If you struggle with handholding them steadily, and the extra weight that comes with the stabilization system isn't an issue for you, and you don't mind changing batteries, then those might be something worth considering. But it wasn't something I felt I needed. Canon's 10 x 42 L IS WP Image Stabilized Binoculars are $1,499 are an example.

Other reputable camera brands also make good binoculars. I looked at other similar high-quality models in a similar price range, including the Nikon 10 x 42 Monarch M7s that retail at around $497, but I discounted those because the grip seemed not as good as the Olympus. I looked online at the Fujinon 10x42 Hyper Clarity Binoculars, and those were far more expensive at $849, but they also seemed not to be rubberized.

The Olympus 10 x 42 PRO are light and comfortable to wear.

Although costing far less than the $3,369 Swarovski equivalents or the Steiners at $899, with a recommended retail price of $499, the Olympus 10 x 42 PRO binoculars seem superb value. It's worth shopping around and asking for price matching. The Olympus binoculars are currently on offer at a reduced price here in the UK, and you may find similar offers in your corner of the world. However, if that is still outside your budget, I have previously tried some models from the Olympus S range in a camera shop and, although not in the same class as the PRO binoculars, seemed superb compared to much of the similarly priced competition.

Whatever you go for, do choose a known brand, as the build and image quality is miles ahead of the cheap, obscure manufacturers. Those are a false economy.

For openness, I am now an OM System Ambassador, a role I recently took on because of my belief in the OM System's outstanding quality and my familiarity with and long-term use of its camera equipment. You can read more about what that means here. However, that has not influenced my opinions of these binoculars. I am happy to own them and would gladly recommend them on price, weight, build quality, and, most of all, image quality.

You can buy the 10 x 42s by clicking here and the 8 x 42s by clicking here.

Ivor Rackham's picture

Earning a living as a photographer, website developer, and writer and Based in the North East of England, much of Ivor's work is training others; helping people become better photographers. He has a special interest in supporting people with their mental well-being through photography. In 2023 he became a brand ambassador for the OM System

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For low light use, the binocular exit pupil is more important than the objective lens diameter. The exit pupil size determines how much light actually reaches your eyes. This would be more comparable to a camera lens aperture. The objective element size is just the front glass element. A big front element does not necessarily equate to a wide exit pupil.

In low light your eyes' pupils will dilate. It is important the the binoculars exit pupil are larger than your dilated eyes. Or else you can actually see the edges of narrower binocular pupils and they will be letting in less light than your eyes could potentially use.

Sorry, but doesn't work this way (I studied optics).

First things first: if you compare binoculars yielding the same magnification, the amount of light collected depends mostly on the square of the diameter - so 42 mm binoculars collect ~2.6x more light than 26 mm binoculars. And that matters a LOT more than optical quality.

The edges you see when looking in binoculars aren't related to exit pupil and image brightness, but to the field of view of the eyepiece (the "thing" you're looking into). You can have eyepieces with different fields of view, while keeping the same magnification and exit pupil (think of exit pupil as camera aperture and field of view as camera focal length).

This is because exit pupil *actually* depends on diameter, since exit pupil = diameter / magnification

So 10x26 binoculars will give you 2.6 mm exit pupils, 10x42 will give 4.2 mm pupils and 10x50 give 5 mm pupils. But the first will collect ~2.6x less light than the second, and ~3.7x less light than the third.

But your eye can't always collect so much light. At night your eyes dilate to ~7mm, but under daylight they might close to ~4 mm (it depends on the amount of ambient light). So at night your eye pupils are big enough to collect all the light coming from 10x50 binoculars (since 7 > 5 mm), and you'll see a considerable difference in brightness between 10x50 and 10x42 binoculars.

At midday your eye pupils will close to ~4mm (which is smaller than 5 mm), and they won't be able to collect all the light coming from the bigger binoculars, so you won't be able to tell the difference.

So under daylight you may be better served by the smaller binoculars, since they will be lighter and easier to hold steady than the bigger one.

I haven't studied optics, but I'm wondering about the condition of one's eyes. LIke the author, I'm older with relatively poor vision and thus question whether my eyes would benefit more than a younger person from a larger exit pupil.

Thank you both for an interesting discussion.

Gerlando, thank you for that fascinating information.

This past year I went through the same process as you, researching models from various manufacturers and came to almost the exact same conclusion: due to my use case, I went for the 8x42, but like you, chose the same manufacturer of my camera gear! ;-) I don't know if they're better or worse than anything else ... I only know I love my Nikon Monarch M7 binoculars. :-)

Thanks for that, John. Those, too, are super binoculars with great reviews. However, when I was researching, I could not find the supplied strap's width, and the loops on the binoculars were big enough to take a camera strap. I would be interested to hear.

The strap is too short and nothing to write home about so I replaced it. The loops are 12mm wide so only take a very modest camera strap.

Thanks for sharing that.

Any items like binoculars that I own stand a fair chance of being lost or badly damaged due to careless treatment, so binos are one of the things that I simply won't spend much money on, despite the fact that I appreciate high quality optics. So I have to get "bang for the buck" binoculars, and the best I have found in that category are the Vortex brand.

I also see the value in large diameter objective lenses (the exit pupil diameter doesn't matter to me). Hence, I will not bother getting any binos that are small and light because I would rather have no binocular at all than ones with small objective lenses.

The Canon Image Stabilized binoculars that you mention, the 10 by 42 model, are incredible! My friend's Dad has those and they are truly a game changer. But way out of my league price-wise for something that I will inadvertently treat with neglect.

Yes, stabilized binoculars interested me, but the payoff of having the extra weight and carrying batteries was too big a disadvantage. Plus, I can happily hold my binoculars on the subject. If I were in a position where I needed to use 16x or 20x optics, then I could see the advantage.

Regarding exit pupil size, Gerlando's comment above is a fascinating read.

Tom, it's too bad that you indulge in "careless treatment!"

I realize certain behaviours are well-ingrained and hard to change, but I appreciate the rewards of treating gear with at least somewhat more care. I don't go overboard about it, but I am still using gear I bought in 1980, and it still works great!

If it matters to you, you can train yourself to be more careful. For example, after an ex unexpectedly dumped my camera bag on the floor, I adopted the "always keep it zipped" rule. Do I miss a shot now and then because of that? Perhaps, but my repair and replacement budget is practically nil!

On a higher level, human impact on our planet is approaching the breaking point. We may lose the ability for high-precision manufacturing in the not-so-distant future. I harbour the somewhat foolish notion that perhaps my well-cared-for gear may someday become a treasure to someone else who otherwise can't get anything decent. Being non-electronic, binoculars may be worth more than gold someday!

I absolutely agree with your sentiments there, Jan. I remember the first time I picked up my camera bag without zipping it up. Oops!
Luckily I was on a soft field and the only problem was the mud I had to wipe off my lenses. Learned a lesson from that.

I'm also a great believer in putting the camera down and just watching. The 3D viewing through binoculars is quite different from the monocular vision of a camera lens and there's no pressure to take a picture.

I used to use binoculars a fair bit before I got into photography. Now I can't imagine carrying them anywhere - If I see something I like, I want to photograph it!

I just spent a few days tramping in Malaysia - Walked 21km with 10KG of camera gear on my first day. I can't imagine adding binos to the load, even at ~650 grams. That's half a litre less water I could carry and you definitely need the water :-)

I absolutely get that. But 10 KG? Ouch! I used to do a lot of hiking in the hills and mountains in Scotland and that would have been more than half the weight of my full rucksack, including a tent, food, and water. I'm still very much into reducing the weight of what I carry, hence the OM1, a long and wide-angle zoom lens, and a carbon fibre tripod. It comes to under 3KG. I agree with you that I wouldn't always take binoculars with me, but sometimes I like to stop and just watch too.

We often get dolphins off the shore where I live. They are usually too far out to photograph but it's nice to watch them. Similarly, the bird hides at our nature reserve are too far from the water and set too high for great photos, so just watching and learning the birds' behaviors with binoculars is a good education for photographing them later. But, as you say, there are times to leave them behind.

Interesting article. I use a pair of, now discontinued, Opticron Traveller BGA Mg 6x32 binos. Made in Japan, nitrogen filled, 30 year guarantee, etc. They’re magnesium bodied, have BAK4 prisms and weigh under 400g. They were £250 RRP and I paid £225 for mine. On top of that, and the main reason I bought them, is that they’re brilliant in low light. I really only need to find things, I don’t need to use my binos to study them, so compactness and low light ability are important to me. I reckon 6x magnification optics are much under-rated and thus there aren’t many about. I’ll be hanging onto these ones.


John, you bring up a good point about how you use binoculars - to find things, but not to study them.

My usage of binoculars is as opposite from yours as can be. I find the animal with my eyes, and they use binoculars to study it is as great detail as possible. That is why I use larger, heavier binoculars and always try to have a support to rest the binoculars on for the steadiest viewing possible. I mean, I want to look for tiny plumage details on small birds at 100 yards away - you know, so that I can tell one Mallard duck from another Mallard duck, or to estimate the length in inches of each tine on the antlers of a Whitetail buck form 300 or 400 yards away - the tiniest details that distinguish one of a kind from another of the same kind.

I would like to know what you are finding with your binoculars - are they wild animals, or other types of subjects?


That's interesting John. My understanding is that the low-light performance depends upon the objective lens size. Have you compared them with the low-light performance of those with a larger aperture? Sadly, you are in the opposite end of the country from me - you couldn't get much further - otherwise, we could meet up and compare. Thanks for taking the time to comment.

I must disagree. I find the Canon IS series to be functionally so much more useful, particularly in more difficult situations, on a boat, on safari etc

Agree. People who say IS doesn't make a difference with binoculars aren't using their binoculars in super-challenging conditions where there is no way to hold them steady.

I used to live in Tanzania and never found the lack of image stabilization an issue then when I was out in my Land Rover. Saying that, I would invariably stop driving to use them so was on a stable platform. I would never recommend passengers holding a camera or binoculars to their eyes while a vehicle is moving either, especially not over rough terrain. The risk of injury is high.

I can see the point at sea for certain uses, such as ornithology. But, like everything they have their advantages and drawbacks. That includes having to carry extra batteries and change them every two and a half hours of use, which is not a great thing to do at sea as the salt water can ingress the electronics that way. Furthermore, at sea, storage space is at a premium.

My understanding is that most Navies don't use stabilized binoculars except in their helicopters, and then they are plugged in on charge. But my information here is secondhand and happy to be corrected.

I agree that stabilized bins have their uses, but not in every case. For example, I wouldn't take them hiking, camping, or canoeing. When weight and portability isn't an issue, then they are a good idea, especially if you need longer focal lengths.

Thanks for commenting.

Depends which option you chose. The canon12x36 II IS weigh exactly the same as the bins you reviewed

But they have far smaller objective lenses so less light gathering ability. Like for like, those without are lighter.

A month later and I tried these against a pair that cost more than double what these do and another pair that were under £100 GBP.

I could tell no difference against the more expensive ones and there was a huge difference against the the cheaper models.

I think, like cameras and lenses, after a certain point you pay 90% more for an additional 10% benefit.

That's a good point, John.

With some things, it's more like you pay 400% more for 2% more benefit. And it is well worth it to those who have the money.

If only we all had access to unlimited funds!

Well, yeah. It's more of a saying than a rule. The first time I read that was in '82, referring to the benefit of 4WD over 2WD.