Linked from
The 6 pages that link to Objective lens, each with the reason it gives.
MicroscopeBroader topic: Its optical properties strongly shape magnification and resolving power.
BinocularsRelated: Its diameter determines how much light each telescope gathers.
Compound microscopeRelated: It gathers light from the specimen and creates the intermediate image.
EyepieceRelated: The eyepiece magnifies the image this component forms.