Do I need another filter if I'm going over a certain number of stops in nd filters?

[leaftors]

I remember seeing a DP put in another filter because he had gone over like 5 stops of nd filters. I think it has something to do with colour change?

 

[David W. Jones]

IR or hot mirror?

 

[Chris Adler]

Yes, it's common to use an IRND (combined filter) starting around 1.2.

 

[leaftors]

I need a 5 stop dif so a 1.5

What happens if I don't use one?

 

[Chris Adler]

There's a big thread that shows the effects of IR contamination the BMCC sensor picks up when you go with a heavy ND without blocking the IR.

 

[visugeek]

Yup, red shift in the shadows. Fix it in camera so it's not a headache in post.