Binoculars for Fishing



Many people choose unsuitable binoculars and this article will hopefully help you avoid making the same mistakes I did.  I’ll try not to go into too much technical detail but still give you enough information to make an informed choice.  If you do want more of the technical stuff see the appendix at the end that I’ll be adding soon.

Understanding Binoculars

Binoculars are described by two numbers separated by an x, for instance 7×50 or 8×40.  Incidentally, the x is pronounced “by”.

The first number is the magnification, which for handheld binoculars is likely to be between 6 and 12.  The higher the number the greater the magnification but the harder they are to hold steady and the less you can see at once of a scene.

The width of the scene is called the “field of view”.  Quite apart from showing more of the scene, a wider field of view also makes it quicker and easier to find what you’re looking for, plus makes it easier to track a moving object.

The second number is the diameter in millimetres of the lenses furthest away from your eyes.  These lenses are called “objectives”, whilst the lenses nearest your eyes are called “eyepieces” or sometimes “oculars”.

Objectives for handheld binoculars will typically be between 20mm and 56mm in diameter.  The larger they are the more light they’ll collect but the bigger and heavier the binoculars will be.

There’s no universal agreement, but binoculars with objectives less than about 30mm are usually called compacts.

How bright the view appears will partly depend on the quality of the binoculars and also on what is called the “exit pupil”.  The exit pupil is simply the objective size divided by the magnification.  For instance 10×50 binoculars will have an exit pupil of 5mm (50 divided by 10).

The larger the exit pupil the brighter the image will be. However, there’s a limit.  This is because there’s no gain in brightness if the exit pupil is wider than the pupil of your eye.

So just how wide is your pupil?  It varies from person to person, but in bright light your pupils are likely to close down to less than 2mm.  At dawn and dusk they’ll open to about 5mm.  Once you’ve adapted to darkness they’ll open up to about 7mm.

What isn’t commonly known though is that as you get older your maximum pupil size tends to gradually diminish.  Again everyone is different, but by the age of 65 your pupils may not open to more than 4 or 5mm, and it can get even worse at older ages.

This is more important than it first appears.  A young person is likely to get the full benefit of say 8×56 binoculars that have an exit pupil of 7mm.  An older person whose maximum pupil size is only 5mm won’t.  With the odd exception he or she might as well buy a pair of 8x40s that have an exit pupil of 5mm and save on size and weight, not to mention cost.

See the appendix for more on the exit pupil, including if you want to look at the stars or use binoculars from a vehicle or boat.

You’ll by now have realised that with binoculars everything is a compromise.  What spec to choose depends very much on both the individual and the intended use.

What’s Best for Fishing?

Like many anglers I thought I wanted compact binoculars for fishing from the bank because of their small size and weight.  If I were desperate to travel light or going on a hiking holiday I still might think the same.

However, to my surprise, I’d found that compact binoculars didn’t perform as well as larger ones, even in bright light.

In case it was just the various compacts I’d used, I went into a camera shop and spent ages looking through lots of different sizes and makes in various price brackets.  What I found was that for a given magnification I could indeed see more detail through the larger binoculars – even outside in full daylight.

The reason turned out to be a surprising one.  Up to an objective size of about 42mm, I could actually hold heavier binoculars more steady – presumably because of inertia, it taking more force to start them shaking in the first place.

We’re all different as to how steady we can hold binoculars but I found that, for me, 8x magnification was the optimum.  I couldn’t see any more detail through 10x binoculars than 8x ones, again because of shake.  On the other hand, as already explained, higher magnification means a smaller field of view.  Additionally the view with higher magnification may well not be as bright at dawn and dusk, which of course are prime fish-spotting times (see the earlier exit pupil discussion).

There is one way round this though.  Image-stabilised binoculars allow you to hand-hold higher magnification binoculars without shake.  Canon are the market leaders here, and I have a pair of their 12x36s that I can thoroughly recommend and I’ll review in due course.  However they aren’t waterproof or fog-proof, nor do they focus closer than 20 feet (6 metres).  They’re also very expensive (I paid £630).  For my other hobby of astronomy though they’re brilliant, and I do often take them fishing with me in good weather.

By now though I’d decided that the ideal specification for my all-weather fishing binoculars was 8×40 or 8×42, which are also popular with birdwatchers.  However, although I was happy with the heavier weight, I still wanted them to be as compact as possible.

There are 2 styles of binoculars, traditional Porro prisms and modern roof prisms (see photos as soon as I’ve taken them!).  The latter are more compact and also easier to make waterproof and fog-proof (so they don’t steam up internally in humid conditions).  So for these reasons I decided on roof prisms, at least for fishing binoculars.

How much do you need to pay?

Thankfully, the price of binoculars has come down a lot recently, in as much as former advanced features are now available in much less expensive pairs.

I tried a large number of models, starting at the lower end and gradually working up.  What I found was that there’s a big difference in quality as you first go up in price. However, as you go further up the scale you need to pay a lot extra for just a small improvement.

At the very least I suggest you look for fully multi-coated optics (i.e. not just multi-coated, nor just fully coated) as these will give you a much brighter view, especially in poor light.

If like me you decide on roof prisms also look for “phase-corrected” prisms (see the appendix if you want to know what these are).  Phase correction is one feature I certainly found it worth paying extra for.  Porro prisms don’t need phase correction though, and this is one of several reasons why they tend to be cheaper than roof prisms of the same quality.

Is it worth paying more for other improvements?  Certainly more expensive binoculars are likely to be a bit brighter, sharper and more contrasty.  However, as I said earlier there comes a time when you have to pay a lot more for just a small improvement in quality.  Only you can decide if you can justify extra, especially for binoculars that are likely to get knocked about.

For many of us the “sweet spot” is currently about £150 – £200.  Here you’re likely to find roof prism models that are not only rubber-coated, waterproof and fog-proof, but are also fully multi-coated and have phase-corrected prisms.  However there are an awful lot of such binoculars to choose from in this price bracket!

To decide which binoculars are for you I can’t stress enough that you should try as many pairs as possible.  This is because, like clothes, binoculars are very personal items, and they have to fit you.  In particular they have to fit the shape of your face, and so what suits me or any other reviewer may not suit you.

If you wear glasses or Polaroids

It’s better not to wear your glasses with binoculars unless you have to as they’ll slightly degrade the image.  However you may or may not be able to get away without them.

If there’s anything in the CYL part of your prescription then you have astigmatism, and many articles say you should then always wear your glasses when you look through any binoculars.

However, this is not quite correct as it depends on the amount of astigmatism and the exit pupil of the binoculars.  The smaller the exit pupil the less likely you are to need your glasses.

Tests show that if you have the minimum amount of astigmatism (0.25 on the CYL part of your prescription) you’ll only be able to just notice the astigmatism with an exit pupil of about 7mm or more.  With 0.50 on your CYL prescription this drops to about 4mm or more, 0.75 to about 3mm or more, and 1.00 to about 2mm or more.  Bear in mind that this applies to your worse eye.

If you don’t have astigmatism you probably won’t need to wear your glasses.  However it’ll depend on how long or short-sighted you are.  This is because to a certain extent you can correct for long and short sight (but not astigmatism) when you focus the binoculars.

However, the maximum amount of correction varies from model to model, even in the same range of binoculars.  If you’re eyes are markedly different to each other you may not be able to get the image focussed in both eyes at the same time without your glasses.  And if you’re moderately short-sighted or worse, without your glasses you may not even be able to focus at or near infinity at all!   This is therefore yet another reason to test binoculars before buying.

Additionally, it’s important if you wear glasses that you buy a pair that has enough “eye relief” (see the appendix for more information).  Without sufficient eye-relief you won’t be able to get close enough to the eyepieces to see the full field of view.

Too much eye relief is less of a problem as long as you can adjust the eyecups around the eyepieces enough to avoid “blackouts” obscuring part of the image.   So once again, it’s important to try before you buy.

The eye-relief will be quoted by just about all makers, but in my experience it’s only a guide as there doesn’t seem to be a common standard.  How much eye-relief you’ll need will depend on the eyecups of the binoculars, the style of your glasses (see the appendix) and, again, on the shape of your face.  At the very least, if you wear glasses you’ll need a minimum of 14mm of eye relief, and many people will need more.

So what did I end up buying?

Opticron Discovery 8×42 WP PCs.

These had been on my short list as, although not quite top, they’d done very well indeed in head-to-head resolution tests.  They also turned out to have a somewhat brighter and more contrasty image than some others I tried in the same price bracket.

They’re also very compact at 133 mm long x 126 mm wide x 52 mm deep (5.2 x 5.0 x 2.1 ins). In fact I haven’t yet found any smaller 8x42s, even amongst much more expensive pairs, and they’re actually smaller than some 8x32s!  At 703gms (24.8ozs) they’re slightly heavier than some other small pairs of this spec, but as discussed earlier I could hold them steadier.

If you decide that even these are too big or heavy for say hiking take a look at the even tinier 8×32 Discoveries that are smaller and lighter than some compacts!  However, as already mentioned, I could see more detail through the 8x42s.

The supposed eye-relief on the 8x42s at 22 mm is very long.  That said, although longer than others I tried, it didn’t seem hugely so, and I think Opticron are being less strict than some other suppliers.  More importantly though, with the eyecups adjusted almost right down I’m able to see the full field of view with my glasses on.

This field of view is a little wider than average for 8x binoculars at 7.5 degrees (393 feet at 1000 yards or 131 metres at 1000 metres).

They also focus significantly closer (4.9 feet or 1.5 metres) than any other 8x42s I know, again regardless of price, making them ideal for looking at nearby dragonflies for instance.

Mechanically they’re very good, and once adjusted everything stays put, whilst the focus wheel is easy to use without any sloppiness.

One other thing I like is the large eyepieces.  I found these helped me hold the binoculars more steady.  As I said earlier though this will vary from person to person – large eyepieces might not suit someone with a big nose or closely-spaced eyes.

If you have got closely-spaced eyes you need to be aware that you might not be able to fold the two barrels of some binoculars close enough together to see through them properly.  The reverse is so if your eyes are particularly widely-spaced, although this is less likely. To help with this the Discovery 8x42s have a very wide adjustment for “inter-pupilary distance”, in particular going down to an unusually closely-spaced 53mm.  This also means that they can be used by younger children than other models.

What about the downsides?  Whilst everything is good optically and mechanically I’m disappointed with the plastic-coated case that’s peeled apart after only a few months.  Opticron needs to put this right as it gives the (incorrect) impression that these are cheap binoculars.

Although in the UK there’s a 5 year parts and 2 years labour guarantee it doesn’t unfortunately extend to carrying cases, nor straps, eyecups or rubber coatings.

Some other companies do better here.  For instance, one of Opticron’s main competitors, Vortex, gives an unlimited lifetime guarantee if you buy through any of its authorised dealers, though again with similar exclusions except that they cover rubber coatings.  However their guarantee even includes accidental damage!

Granted the street price of the equivalent Vortex model, the excellent Diamondback New, is a little higher than the Discovery (for which I paid £159).  I’d rather have at least the option of paying a little more for a better guarantee though – please note Opticron!

Overall though I’m very pleased indeed with my Opticron Discovery 8x42s.  They provide a very good image compared to many in their price bracket, and indeed better than some quite a bit more expensive pairs.  Additionally, I find them very comfortable to use even with glasses and relatively easy to hold still.  I also appreciate the close focussing, and in particular the small size for 8x42s.

Don’t forget though – whilst these binoculars suit my eyes and the shape of my face they might not suit yours.  So don’t buy sight unseen unless the supplier has a very good returns policy.  Better still,  go into a camera or specialist optical shop and try out lots of pairs.

Technical appendix

Coming as soon as I have time to write it!

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