For anyone following this thread who doesn't know how to use LAB mode:
I found out about it from Louie's video here:
https://www.youtube.com/watch?v=fE2GS_87Ct8
His whole series is here & I think they are all essential:
https://www.youtube.com/channel/UCJ5...Ge66vsuSaXb-0A
cheers
Allan