Delay in shutter release of NIKON D71 overhead flash

Please add the following questions:

1. Does the flash support TTL? Do you support high-speed synchronization?

2. Does the lag of shutter release mean that the shutter cannot be pressed? Or is the shutter speed too slow?

I'm a wedding photographer, and I often encounter the shooting of hotel environment.

I'll give you a preliminary answer:

AF-A spotting mode may be out of focus in the hotel's low light environment, so it's better to choose AF-C mode

general flash, which only supports 1/25 at most, and does not support TTL flash, so the camera can't detect it, so the camera is based on "no flash" when metering, so it must be at the aperture.