What Dolby Vision settings should I use?

I just bought an 120" UST ALR screen. I’m fiddling around with the settings and I noticed that there are Dolby Vision settings that set’s the screen size and the gain. My screen has a gain of 0.85… am I correct to assume that I should use a 120" size and 0.8 gain setting for my screen?

I would like to know this too. I have a 100" ALR screen and left it at 1.6

Not claiming to have solved it… but here’s an opinion I’ve formed after a month. Yes, it is also my understanding that this setting should be used to match the projector to the screen gain and size. I think you need try the setting and watch a variety of DV content to see if you like the end result. For me I have a 92” ALR screen rated at .6 gain. When I matched that screen size and gain using the setting, it looked fine on the apps streaming natively (Apple TV +, Amazon Prime, Disney). However I noticed some rather ugly effects in very dark shows on Netflix and Disney (also in DV on Apple TV 4K). Very elevated dark levels that caused weird patterns. Of course I don’t know if this an issue with the way Apple TV outputs or what; but returning the gain to around 1.8 looks better for that device. I’m just hoping this will be handled well when the native Netflix app becomes available.