An object can be focussed generally

An object can be focussed generally no closer than
250 mm from the eye (depending upon how old you
are!)
• this is considered to be the normal viewing distance
for 1x magnification
• Young people may be able to focus as close as 125
mm so they can magnify as much as 2x because the
image covers a larger part of the retina - that is it is
“magnified” at the place where the image is formed