CREATE TABLE table_79373 ("Brand" TEXT, "Product Name" TEXT, "Focal Length" TEXT, "35mm EFL and equivalent aperture" TEXT, "Max. aperture" TEXT)

What is the brand of the Sigma 30mm f2.8 DN, which has a maximum aperture of f /2.8 and a focal length of 30mm?
SELECT "Brand" FROM table_79373 WHERE "Max. aperture" = 'f /2.8' AND "Focal Length" = '30mm' AND "Product Name" = 'sigma 30mm f2.8 dn'
SELECT "Brand" FROM "table_79373" WHERE "Focal Length" = '30mm' AND "Max. aperture" = 'f /2.8' AND "Product Name" = 'sigma 30mm f2.8 dn'