Wearing glasses is not a big drawback when it comes to using binoculars. In fact, you can even think of it as easier, since you probably won’t have to mess with extending and adjusting eye cups (sometimes called eyecaps) because your glasses automatically keep the binoculars at a proper distance from your eyes. Typically, keeping the eye cups collapsed (not extended at all), or locked down in the case of turn-and-lock eye cups, gives people who wear glasses the best view. However, experimenting with different eye cup positions could result in a larger field of view. Also, you may find that prescription glasses with the lenses set fairly close to your eyes work best when you’re using binoculars. If the “eye relief” is too short, your view will suffer from an effect called tunneling, in which you only see the middle of the scene you’re observing. To avoid missing out, make sure your eyes are the ideal distance from the eyepiece, whether you’re wearing glasses or not.
Experts such as Michael and Diane Porter, who write for Bird Watcher’s Digest, recommend that glasses-wearers use binoculars with long eye relief of at least 16mm. Folding eyecups might not collapse enough to provide people who wear glasses with the proper distance from the eyepiece. Eye relief should be listed in the product specs for any good binoculars.
If you don’t wear glasses all the time, or switch between glasses and contact lenses, you will need to adjust your focus, including the diopter, when your vision changes due to corrective lenses. It’s not a great idea to take your glasses on and off during a viewing session. Just get comfortable using binoculars with your glasses on. If you’re constantly switching around, you risk missing the bird or action you want to see!
One great source of binoculars reviews is the Cornell Lab of Ornithology’s publication, The Living Bird, which includes “eyeglass friendliness” as a category in its reviews.
