Sony SEL90M28G - A-mount and E-mount Sensor Sizes; Identifying A-mount and E-mount Lenses

A-mount
[1] Lens mount [2] Flange back distance
[3] Translucent Mirror [4] Image sensor plane
E-mount
[1] Lens mount [2] Flange back distance
[3] Image sensor plane

 Image sensor size
Both A and E mount cameras have full frame and APS-C sensors options. Among the
many sensor sizes in common use, full-frame is considered to be a large format while
APS-C is a medium format. Both are popular for their individual advantages.
 About A-mount lenses and E-mount lenses
Sony provides A-mount lenses and E-mount lenses that meet each mount standard for
camera bodies. The name of an A-mount lens starts with “SAL” while the name of an E-
mount lens starts with “SEL.”