- Self Illuminating - if the light path of obj to eye is reversed can see that all incoming light is focused at the plane of the magnifier
- Height of a flat field magnifier can be less than, equal to or greater than r (radius)
M = nr / nr + l (1-n)
for a hemi-spherical magnifier where thickness = radius of curv
t = l = r
The thicker a flat field magnifier is in relation to r the greater the magnification. The image is formed very close to the object so there is no relative distance magnification. Patient must wear near correction. Also you can have bar magnifier with magnification in one direction only - plus cyl lens
Advantages
- Normal reading posture
- Very bright - gathers light
- Good for px w/hand tremor
- Clear image across the lens w/minimal aberrations
- Combine w/spec mounted to get good mag while maintaining fairly distant viewing
- Large lenses - heavy
- Magnification typically low
- Reading Material has to be flat and on firm surface
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