What is the widest lens offered for canon (by any manufacturer) that has an aperture of 1.8 or lower?
This and all similar questions are best answered by looking at websites designed for the purpose. One approach is to look at vendors like B&H Photo, which offers convenient filtering. For example, Canon EOS EF or EF-S lenses classified as "wide" or "wide zoom" with an aperture of f/1.4. Or, use a website dedicated to the task, like the Neocamera database. For example, results for Canon mount, 24mm or wider, and f/2 or faster.