Related Clues:

• Part of a focus group?
• Photog's gear
• Glass in eyeglasses
• Bifocal, for one
• Chip in a Dell, briefly
• Projector part
• ___ cap
• See 23 Across
• Cell-phone feature
• Pince-nez part
• ''Telephoto'' or ''contact'' ender
• Literally, ''vault''
• You see right through it
• Focusing device
• PC brain