What should be my ideal screen brightness for 4k HDR content on a 150" screen?

[imgqtr]

Dear members,
I am thinking to upgrade to a 4k projector. My current screen is Elite Screens EZ Frame 150" CineWhite (gain 1.1). My cinema room is completely light-controlled (bat cave). What should be my target brightness (ftL) on this screen in order to watch HDR content properly?
Of course HDR content and DTM issues are relatively new topics in the home projector area and I couldn't find any consistent advice on this subject. I am using Epson TW9000 SDR projector and I want deeper blacks in my next projector.
I will be grateful for all of your answers.

 

[swiftpete]

I also have a pitch black treated batcave and 150 inch screen. I have an epson TW9400 projector. Unfortunately when in digital cinema mode and medium lamp even with iris fully open and hdr slider on 1, it only measures 32 nits (9.3 ftL) maximum. On natural mode it gets up to 60 (17.5 ftL). I’ve read that ideal target is 100 nits but no chance of that at this screen size. High lamp would probably get closer but way too noisy for me.

I’ve been persevering with digital cinema for hdr for a while as I preferred the colour but it just isn’t bright enough no matter how much I tell myself it is, so recently have started using natural for everything and do prefer it as I can actually see what’s going on in my games etc!

I’m going to calibrate it for sdr and hdr with natural mode and save each as a preset to switch between the two. It is a compromise but no other choice at this screen size unfortunately. I can’t go back to a puny 120 inch screen now though so will keep the big screen.