There is a common habit that one pulls off his glasses or puts them on top before his eyes approach to the binoculars. It would not be a big problem unless you have to repeat this process too much when you walk in the wilderness area or worse, unintentionally lost glasses. Even if you use contact lenses, you still need to blink frequently to keep moisture to the eye. At that time, using spotting scopes will limit somewhat the blink and you’ll soon find your eyes dry.
In summary, spotting scopes are very inconvenient for people wearing glasses. But if you still want to own a spotting scope used in travel, there is a parameter you should know when buying this optical gear.
This parameter represents the distance between the viewer’s eyes and the closest lens in the spotting scope at which the viewer’s eye can obtain the full viewing angle. If the user’s eye is outside this distance, he will obtain a decreased field of view. It is quite complex to calculate the eye relief, though generally, the eye relief is inversely proportional with the magnification and the intended field-of-view.
This is a very important indicator for the glasses wearer because it shows the appropriate distance from which the spotting scopes bring the best image to the eye.This parameter is greater means you can keep the spotting scopes farer away and still see the image.
Normally, an eyeglass wearer’s eye is further from the eyepiece. Therefore, in order for him to see the entire field of view, he needs a longer eye relief. Simply, you can check whether the glasses limit the field of view or not by conducting a two-step test in which you first view without your glasses and then view again with them. It will be ideal if there is no difference in the field of view in the two steps.
This is very beneficial for people carrying glasses, because you do not need to remove your glasses, but put the spotting scope right before the glasses and look around. Despite such importance, this is the parameter that people often overlook.
How much distance is reasonable?
Normally, you need to find spotting scopes that show this parameter in about 14 – 15 mm, which is widely applied in ordinary spotting scopes. But the most ideally, the distance should be over 16mm.
Also, you should check your eyesight before purchasing a spotting scope. Ask the salesperson for advice on how to choose a spotting scope with appropriate parameters for your eyes.