Wonderful photographs! Hard come by I am sure.
I think Eric is right to say that forest owls generally stay hidden through the day- especially at this time of year when presumably, they have young in the nest. Wood owls that I have seen in Borneo roost in dense foliage in the day and become active towards dusk. This is certainly the pattern of calls that has been seen in Lam Tsuen- calling from dusk through to dawn (although it has been very quiet recently- a result of leaving for TPK or breeding?)
Dylan