reflection image when shotting flames

[Yaron Harel]

hi all.
one of our costumer try to shut a frame that the lower half of the frame light with flames and the upper half is dark the flames are feed with diesel fuel and there is diesel fume above the flame.
when they look at the monitors they see an image reflection of the flames on the dark half of the frame and they see it also in the camera PB (they haven't try PB on RED cine or RED alert).
did anyone ever bump in to such phenomenon?
thank, Yaron.

 

[Nick Gardner]

What lens, what stop, and what filters? Most likely a lens issue not a digital one.

Nick

 

[Brent J. Craig]

This was a problem before they moved the OLPF, but there shouldn't be any of those cameras in the wild anymore.

 

[Paul Kalbach]

Were you using a hot mirror filter? If so, and it's not in front of other filters or if it's oriented backwards, it can cause reflection problems.

 

[Yaron Harel]

I'm copying the answer of Keith Walters and I think that this is the answer.
"Sounds like the old infrared problem.
Invisible infrared light from the flames might be reflecting off the smoke and fumes.
Your eyes don't see it but the camera does.
Are they using NDs?
If so, the problem is that most NDs were only designed to reduce visible light, since until single-chip cameras came along, most cameras did not pick up infrared.
If this is the problem all they can do is either get better filters or a hot mirror, or use the lens iris to reduce the exposure and live with the large depth of field."
Thanks all, Yaron.