The default thumbnails are set to show two different pictures of a camera:
The Picture Present Indicator:
Indicates that the HomeStuff database has a file name value in either the Picture or Receipt field and that the file is present but that the "Generate Thumbnail" setting is OFF.
The No Picture Indicator:
Indicates that the HomeStuff database does not have a file name value in either the Picture or Receipt field of the current item.
The Missing Picture Indicator:
Indicates that the HomeStuff database has a file name value in either the Picture or Receipt field of the current item but that the physical file is missing.
Notes: The Picture and Receipt fields are monitored separately.