Spectacles and binoculars - does this combination work?
Binoculars and spectacles wearers: sometimes a problematic relationship. There is one fact that you should pay special attention to.
Some people want to wear their spectacles when observing with binoculars. However, this is usually not necessary, provided that the spectacles wearer is either purely long-sighted or purely short-sighted. If this is case, the wearer can remove their spectacles and adjust the sharpness with the focusing wheel and dioptre adjustment. Even if you have a slight astigmatism, you can still observe without your spectacles. However, if your astigmatism is a little higher at maybe 1 or 2 dpt, it makes sense to wear your spectacles when observing. Astigmatism is the second value on your glasses prescription and is indicated by the abbreviation CYL.
- OD SPH -4.5 CYL -2.0 Axis 90°
- OS SPH -3.0 CYL -1.5 Axis 110°
This is an example of a typical prescription, as you might get from an optician. The value following CYL indicates the curvature of the cornea. If this value is fairly high, maybe 1.5 dpt or more, observing with spectacles is recommended.
For this purpose, some binoculars have an exit pupil that lies further back from the eyepiece, so that the entire field of view can be seen even when wearing spectacles. Since the distance between the eye and the spectacle lens is around 16mm, this longer eye relief is important. Otherwise, you would suffer a sort of keyhole effect. Small, compact binoculars in particular are not usually suitable for spectacles wearers.