Mosseltje
Registered
Not true. The focus light has a sensor and when the flash fires the focus light turns off for 1 second or so. The whole process of TTL is driven (on most underwater camera systems) by light from the flash using optical fibre, and it all happens at the speed of light. As quick as the light from the strobe reaches the subject the Focus torch will be off and have no impact on the TTL sensing, or in manual provide no 'additional' light. The issue with the focus light is it creates uneven lighting, red or white, the aim of the strobe is to provide an even light, so two is better!
Mine only turns off if the relative light of the flash to ambient is 'high', so in bright conditions it says on but the image is not affected, in dim conditions or night it turns off. I use the Focus Light on every photo, its on for the whole dive.
FIX Neo 1000 Mini WR
There is no mention of pre-flash:
Auto Shut-Off
That little round opening below the two red LEDs may seem innocuous but its full of magic! The Auto Shut-Off (ASO) of the Neo Mini detects the flash from a strobes and automatically shuts off the Mini's red or white light output. This feature frees the photographer from the need to dim their focus light to avoid undesirable side effects in the photo. Without dimming a traditional focus light, you can wind up with excess or conflicting shadows or an undesirable red cast in your photos. With the ASO feature those concerns no longer exist. After about 1 second from the ASO, the Neo Mini turns on again allowing you to capture the next series of shots.
I stand corrected, sir.
Seemingly technology advanced faster than my knowledge.