When I am walking along the magnificent Fife Coastal Path, I often carry a pair of binoculars in my pack.
A good pair of binoculars allow you to see some wonderful sights but not everyone uses them correctly and may be missing out on what there is to be seen.
Over the past few years I have heard from many people who struggle to use binoculars. Everybody has different eyes and it is common for us to have one eye that sees better than the other. Someone may have one eye which is nearsighted and the other may be the opposite and can be farsighted. There are multitudes of variation when it comes to a person’s vision.
The most common complaint from people trying to use binoculars is that they have to keep one eye closed when using them in order to see anything clearly and in focus. This is a common problem and one that is easily rectified.
Choosing the correct binoculars
The first step to solving the problem is to ensure that you have a good pair of binoculars. Cheap pairs tend to have very poor lens quality and they tend to lack one key feature which is a diopter adjustment ring which I will cover later in this post.
I always advise people to look for binoculars that feature a large focussing wheel (also called the fly wheel) that moves freely and smoothly and I also recommend that they choose a pair that have a glare reduction coating over the optics. It is always best to try different binoculars in person before purchasing them rather than buying them from the web and hoping that they will suit you.
I tend to favour 7×32 or 10×50 binoculars where venturing out for a walk. The 7×32 binoculars are small, lightweight and ideal for nature, hiking and sporting events while the more powerful and bulky 10×50 binoculars are more suited to birdwatching and astronomy when you want to pick out fine detail.
In terms of magnification, the 7×32 binoculars have 7x magnification and the objective lenses (the larger of the two lens types) are 32mm in diameter and the 10×50 binoculars have 10x magnification and the objective lenses are 50mm in diameter. There many variations of lens and diameters for all sorts of uses but I have found that these best suit my usage both in the countryside and on the coast.
People often think that moving the focusing wheel is calibrating the binoculars to suit their use allowing them to focus on something in the distance but, as I mentioned at the start of this post, many peoples eyes are different and this is where people start to close one in order to get image.
The key to calibrating your binoculars for your use is the diopter adjustment ring. This ring is often found on the right ocular or eye piece (see picture) and can be identified by the presence of a plus, minus and 0 (or arrow) markings. This marked ocular also rotates.
Adjusting the diopter
Provided you are the only one using your binoculars, you should only have to adjust the diopter once but the process is easy enough to repeat should you need to e.g. when you lend your binoculars to someone else.
1 – Look for a fixed object that is approximately 10m away from you (around 30ft).
2 – Look through your binoculars and close the eye that has the diopter adjustment ring (often the right eye) and using the focussing wheel bring the object into focus for your left eye. Try to get the image as sharp in focus as possible.
3 – Open your right eye, close your left eye and take hold of the diopter adjustment ring. Slowly turn the diopter until you bring the object again into sharp focus.
4 – Now with both eyes open you should have a pair of binoculars that provide you with a perfectly focussed image for both of your eyes.
Once you have calibrated your binoculars to your eyes, it is best to keep them stored in a case to prevent the diopter ring from accidentally being moved and losing your calibration. If you do find that you have lost focus then simply follow the steps again.
I hope that this quick guide will help those of you struggling with your binoculars but if you have any questions then please email me at email@example.com
Jim Beatty – Walk Fife