Sony a7iii: What is the flash that happens in this clip?

[Henrydavidt]

Whenever I zoom in, the flash of light happens. Im already set on Manual Exposure. What am I missing?

Metabones EF-E mount T Canon EF 16-36mm set to manual Aperture is 5.6. When I crash zoom the F5.6 flashes off, then when the camera ‘finds’ the exposure again returns to this figure. Picture profile is off (same flash happens on every PP) Manual Exposure set to M Wheel is set to Video (same flash on M mode) ISO is 125 (same flash on other ISO) 1/50 (same flash on other shutters)

[XKAES]

Read your manual.  Some cameras send out a flash of light to aid in focusing -- especially in low light.  If that is the case, it will not impact your exposure.  And you might be able to turn it off, but that depends on your camera -- so again, check you manual.

[Henrydavidt]

Thanks for the response. I should have been clearer, I have read the manual and Im still none the wiser. The 'flash' does impact the exposure, that's why I'm asking for help. Also, it's the Sony a7iii (as displayed in the post title), Im not aware that this camera sends out a flash to aid focusing. Happy to be corrected if it helps this issue though! Many thanks

[XKAES]

OK.  What flash MODE(s) are you using when this happens?

[Pieter]

For some reason the camera seems to open the aperture for focus acquisition, and then closes again when focus is found. This is causing a sudden heavy overexposure (or flash). For photography this is normal but your viewfinder is compensated for this so you normally won't notice it. I guess your Metabones adapter has something to do with it. Does it also happen with native E-mount lenses?