If you are already familiar with binoculars or cameras, you may have probably adjusted the diopter already knowingly or unknowingly. Whether you are a newbie or a Pro, here are steps on how to adjust diopter on binoculars properly.
What is a Diopter and Its Purpose?
The diopter is a control knob for adjustment that is meant to compensate for the differences between your eyes in your binoculars. Basically, it is a measure of a lens’s optical power which is determined by its focal length. A higher diopter means a stronger lens and correction.
Most often than not our eyes strengths are not always the same. You will find that one of your eyes is weaker than the other. Especially when you are looking through equipment that has magnification. The optics exaggerate the eye focal differences. This may lead to eyestrain.
Many of us actually do not know that our binoculars have that diopter adjustment in them. When you focus the binoculars and look through them, you might realize that you can’t still see properly through them. This makes many people think their device is probably spoiled when in actual fact, all they need is to just adjust their diopter to compensate for the difference between their eyes for them to see properly through their binoculars.
The human eyes can never actually focus at the same distance at the same time.
How to Adjust the Diopter- Step by Step
When it comes to the binoculars adjustment, there are two places you can often find the diopter on your binoculars. On some binoculars, you will find it on the right eyepiece and on others it is placed on the central knob.
You will often identify the diopter my its marking. It is marked with +/- on the wheel.
Adjusting the Diopter on the Right Eyepiece
Before you start tuning the diopter knob, first use the binoculars central focusing knob to focus both eyepieces at the same time. Check out this article on how to focus your binoculars if you don’t already know how to go about it.
After you can now adjust the differences between your eyes by adjusting the diopter on the right barrel to fine-tune it one time. Once it is tuned, the two barrels will stay focus together whether you are looking at short or far distant objects.
You start by setting the diopter to zero or its central position. Different binoculars have different symbols to indicate the central position. Some have zero indicator others different symbols. the wheel or ring can be turned either right or left to achieve this position.
Using a lens cap, your hand or any dark cover, cover the barrel which the diopter affects. Mostly it is the right eyepiece.
Put your binoculars over your eyes and look at a stationary object in the middle from a distance. Keep both eyes open and focus your binoculars using the central focusing knob until you get a clear and sharp image. Do not focus your bino using moving object and don’t keep one eye closed and squint. As the pressure on your eyeball may temporarily change shape and make it focus differently.
Once your left eye is correctly focused, you can now use the diopter to adjust the right eye. Be careful to leave the central focus the way you have just set it. Do not adjust it again. Now switch the lens cap to the other side so you can see through the barrel.
Staying at the same place, look at the same object you looked at before. even though you are looking with both eyes you will only see with one eye(the right eye).
To now fine-tune for the right eye, turn the diopter setting back and forth until you obtain the sharpest image. while doing this, do not focus the central focusing system. Once, the image on the right eye is very sharp, you can now remove the lens cap from the other barrel and look through with both eyes. The image should be sharp and comfortable to look at this time.
You have correctly adjusted the diopter on your right eyepiece.
The Diopter Adjustment on the Central Column
Some binoculars have their diopter adjustment on the central column. However, the technique for adjustment is the same as the ones with the diopter on the right. Just follow the same steps.
- Set it at zero by placing the index mark on the focusing eyepiece opposite the zero or middle on the scale.
- Using the central focus knob that moves both eyepieces, focus on a distant object such as a leaf, rock, or star. Be sure it’s sharp in the fixed eyepiece.
- Turn the diopter adjustment until the other eye, too, has a sharp view. The number on the scale is the diopter correction for that eye relative to your other eye; it’s probably close to what an eye doctor may have measured for your eyes.
- Remove the lens cap and enjoy the matching view through both eyes at once.
Once you have set your diopter in the binoculars correctly, you don’t have to set it again. You can now use your binos to view long and short distant objects comfortably and with accuracy.
Josephine is Content Manager @ Binocularsinght.com, an Electrical Engineering Grad who loves optics. She is an Outdoor Enthusiast and a Writer who likes escaping into the mountains for hiking adventures and enjoys other outdoor activities as well.