Canon rf s 7 8mm f 4 stm dual vs laowa 11mm f 4 5 ff rl?

7-8mm on APS-C (Canon) gives the view of 11-13mm on full frame. For the same depth of field, f/4 there behaves like about f/6.4 on full frame. Exposure doesn't change: f/4 gives the same brightness on any sensor.

The same view on every common format:

• Medium format (44 x 33): 14-16mm at about f/8.1 for the same depth of field
• Full frame: 11-13mm at about f/6.4 for the same depth of field
• APS-C: 7.5-8.5mm at about f/4.3 for the same depth of field
• APS-C (Canon) (yours): 7-8mm at about f/4 for the same depth of field
• Micro Four Thirds: 5.6-6.4mm at about f/3.2 for the same depth of field
• 1-inch: 4.1-4.7mm at about f/2.4 for the same depth of field
• 1/1.3-inch: 3.1-3.6mm at about f/1.8 for the same depth of field
• 1/1.7-inch: 2.4-2.8mm at about f/1.4 for the same depth of field
• 1/2.3-inch: 2-2.3mm at about f/1.1 for the same depth of field

Crop factors are by the sensor diagonal, rounded as they're usually quoted; a format with a different shape (4:3 against 3:2) frames a little differently across the width. More in the focal length converter.

Computed from the sensor sizes, not written by a model.