question: What camera has the highest Mpix with an aspect ratio of 2:1, a height less than 1536, and a width smaller than 2048?
answer: SELECT MAX(mpix) FROM table_name_51 WHERE aspect_ratio = "2:1" AND height < 1536 AND width < 2048
context: CREATE TABLE table_name_51 (mpix INTEGER, width VARCHAR, aspect_ratio VARCHAR, height VARCHAR)