Tiny opening
Else clues• A poster may have one
• Aperture
• Balloon buster
• Balloon flaw
• Camera obscura feature
• Camera type
• Certain camera aperture
• Film flaw
• Flask flaw
• Homemade camera feature
• It admits very little light
• It's hard to see through
• Small aperture
• Tiny aperture
• Tiny puncture
• With no help, I find opening
• A small puncture that might have been made by a pin