Stacking IR NDs

[Robino Jones]

I am about to buy a set of 4x5.65 Schneider Platinum IR filters to use with a RED Scarlet. (1.2, 0.9, 0.6)

 

My question is about stacking them up.

 

- Is it be better to use a 1.2 IR and a non IR .6 or .9 when stacking-up filters to avoid increasing the green bias? In other words will having 1 stronger IR filter take care of the IR issue in a stack?

 

- ...or should I not even think about stacking NDs and get a 1.8 for outdoor ?