First thing you might want are some indexes.
A Clustered Index on ID in the Places table and a Clustered Index on SID in Phototable would be a start and may speed things up no end.
After that, a simple left join query will help you.
DECLARE @Username VARCHAR(100)
SET @Username = 'Jeff'
LEFT OUTER JOIN
PLACES.ID = PHOTOTABLE.dir
PHOTOTABLE.creator = @Username
PHOTOTABLE.dir IS NULL