Magnifying glasses are often used for viewing three-dimensional objects.
This angle, therefore, divided by the magnifying power of the telescope gives the real angular distance of the centres of a double star.
focal length, having eye-pieces magnifying up to 230 diameters.
In magnifying glasses for direct vision the eye must always be considered.
focal length, with a magnifying power of 38 diameters, which he presented to the Royal Society of London in December 1671.