Kind of figured it out. This code does not give accurate readings for high speeds. The higher the speed the greater the error. The OP's values for the 1/400 are proof of that. Keep this in mind when you decide to test your shutters.
Kind of figured it out. This code does not give accurate readings for high speeds. The higher the speed the greater the error. The OP's values for the 1/400 are proof of that. Keep this in mind when you decide to test your shutters.