Is the laowa 14mm f 4 ff rl zero d good on aps c?

14mm on APS-C gives the view of 21mm on full frame. For the same depth of field, f/4 there behaves like about f/6 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): 27mm at about f/7.6 for the same depth of field
• Full frame: 21mm at about f/6 for the same depth of field
• APS-C (yours): 14mm at about f/4 for the same depth of field
• APS-C (Canon): 13mm at about f/3.8 for the same depth of field
• Micro Four Thirds: 10mm at about f/3 for the same depth of field
• 1-inch: 7.8mm at about f/2.2 for the same depth of field
• 1/1.3-inch: 5.8mm at about f/1.7 for the same depth of field
• 1/1.7-inch: 4.6mm at about f/1.3 for the same depth of field
• 1/2.3-inch: 3.8mm 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.