Only with enough eye relief, and short eyepieces of simple design have very little. If your prescription is spherical you can usually take the glasses off and refocus; astigmatism is the case where keeping them on genuinely matters.
This is the specification that most often decides whether an expensive eyepiece gets used, and it is quoted more loosely than any other.
What eye relief is
The distance behind the eyepiece at which your eye sees the whole field. Too close and the field is cut off; too far and it vignettes. Spectacles push the eye back by the thickness of the lens and the frame.
Which prescriptions need it
Astigmatism, principally. A spherical correction — short or long sight — can be dialled out with the focuser, so the glasses come off and nothing is lost. Astigmatism is not a focus error and does not respond that way.
Where the figure is misleading
It is normally measured from the glass, and what you get is measured from the top of whatever eyecup sits above it. A folding or twist-down eyecup returns that difference; a tall moulded one does not.
What to look for
Designs sold explicitly as long eye relief, and zoom eyepieces read at both ends of their range, since the figure usually changes across it.
The questions that keep arriving
Why can I take my glasses off for short sight?
Because the focuser can compensate for a purely spherical correction: you simply refocus. Astigmatism cannot be corrected by refocusing, which is why it is the case that needs the spectacles to stay on.
Does the eyecup matter?
A great deal. The published eye relief is usually measured from the glass, and a tall fixed eyecup consumes part of it. Eyecups that fold or twist down are what make a long eye relief usable with spectacles.
Last reviewed 17 September 2026