Over the last 2 weeks I have been shooting some tests for a major feature film. The tests involved a special process that involves the use of Infrared light and shooting outdoors.
On the test day we had some fairly bright light levels to deal with. So as you would normally do we added some ND filtration to reduce the light levels. Most of the equipment for the shoot was on hire from Panavision, the main cameras being Panavised Sony Venices with PV70 mounts and Panavison lenses. But for reasons I can’t go into yet, we were unable to use the Venice internal ND filters, so we had to use external ND’s.
The first ND’s we used were circular Tiffen IRND’s that were the correct size for the PV lenses. But much to my surprise these made very little difference to the amount of IR reaching the camera. For our application they were absolutely no good. Fortunately, I had a set of Formatt Hitech IRND’s in my camera bag and when we tried these we got an equal visible and infrared cut. So, the Tiffen’s were put back in their boxes and the Formatt filters used instead.
Back at Panavision we did some further testing and found that both the Tiffen and Schnieder IRND’s that we tested had very little IR cut. But the Formatt Hitech and Panavision IRND’s that we tested cut the IR by a very similar amount to the visible light. In addition we were able to test the Venice built in ND filters and found that these too did a very good job at cutting both IR and visible light by similar amounts.
So, my recommendation is – if you are ever concerned about infrared light contaminating your images use a Venice 2 with it’s built in ND’s, Panavision or Formatt Hitech IRND’s.
Alister,
Do you think that the FX6 NDs will also cut the IR?
I don’t know for certain as it is difficult to remove the IR cut from any of the cameras with a variable ND to test. But I suspect they will cut some but not all. I would not expect a full even response form visible to IR. It is already known that different amounts of variable ND introduce different colour offsets which are then corrected electronically so you don’t actually normally see them. So, this suggests the response across the spectrum is not even.
This sounds like the Day for Night they used in Jordan Peele’s Nope where they used a mix of IR and color.
That and other methods that will have some SFX benefits.
Hi Alister,
Thanks for this post. I totally agree.
I am an amateur videographer, but I always have the Formatt Hitech Firecrest 4×4 filters in my bag (all steps from 0.3 up to 3.0). I really love them. One downside is that they are not really 4×4 (4mm thick), but instead 100×100 (2mm thick). Hence they are not compatible with all matte boxes.
Cheers,
Alex
The firecrests are excellent ND filters. As I understand it they offer 100mm x 100mm x 2mm for use with Lee and Cokin holders etc and then 4′ x 4.65′ x 4mm for use with professional matte boxes etc.
You are absolutely right. But unfortunately many filters are simply called 4×4, even if they are 100×100 (or vice versa). One has to look out for 4mm instead of 2mm thickness. Nonetheless I can use them in my Smallrig matte box which is lightweight and suitable for 2 filters (4×5.65, 4×4 OR 100×100).
For the TILTA MB-T15 it isn’t that easy…