Possible Clues:

• Like photographs of an eclipse, say
• Type of photography
• Not shot all at once
• Snappy way to condense lengthy periods?
• Having an extended opening?
• Of photographic technique of taking photos at intervals
• Photographic technique blurring pale items
• Such a photo mate pasted up in paper at bottom of page
• Photographic technique to show very slow processes in motion
• *Like some videos of growing plants