TRU-CUT IR-750 filter

[Shapour Daneshmand]

What's the use of TRU-CUT IR-750 filter?
when and where would you use it?

 

[Damien Molineaux]

Hi Shapour,
When you use a lot of ND, from ND9 and up, you're cutting light but not infrared, this will cause dark colors to turn shades of red, purple or brown. To avoid this, you either use IRND filters, or add a Hot Mirror or an IR clear filter such as the one your inquiring about.
Cheers,
Damien

 

[Andre W.]

Helps cut out Infrared Contamination in the 750nm wavelength and beyond. Is something that you would use when you reach a certain point with your ND's. Outdoors is a good example....

When you hit ND.9 your balance of visible light and invisible light (invisible to us, but visible to camera sensors) starts to become imbalanced a little bit. You will start to see slight color shifts, blacks going magenta, greens going white, stuff like that. The deeper the ND's the more this imbalance becomes. So say that you had a ND1.2 stacked with a ND1.5. The amount of invisible spectrum is going to be far greater than that of the visible spectrum causing you image color wise to be vastly different and possibly unusable than what you needed.

Different times of day will result in more contamination than others, and you can also get them from different light sources as well.

https://docs.google.com/open?id=0B0C11OPglduLNGk3eVdMSmRlelE

it's a quick little test we did with various different IR filters and an EPIC camera one day... might help give an idea of what it would do, and when you might need it.

Hope this has helped and answered some questions for you.