Formatt non-ND Hot Mirror filter

[Ryan Lightbourn]

Question for anyone who may have some advice:

I found a great deal on a used one of these:
http://www.bhphotovideo.com/c/product/751589-REG/Formatt_BF_77IR680_77mm_Hot_Mirror_Filter.html

Combined with my Hoya ProND's, will this filter essentially do the same as Formatt Hot Mirror NDs, or do I need varying strengths (this one being 680nm)?

Thanks in advance!

 

[ericyoung]

Yes it should work. This is just a Hot Miirror - it only comes in one "strength", and will effectively block all the problematic Infrared light.

 

[Ryan Lightbourn]

Yes it should work. This is just a Hot Miirror - it only comes in one "strength", and will effectively block all the problematic Infrared light.

Awesome, thanks Eric!

 

[Randall Weatherington]

680 nm is right on the edge of visible red with 650 nm being primary red.
The cut off curve on hot mirrors is not a sharp edge cliff like a square wave. It does have a little slope to it.
You may get a slight reduction in visible red which is easy enough to grade back in when in post.
Also be careful about angling the mirror as it will shift the center frequency (680 nm) more towards a shorter wavelength.
This can also happen as a wide angle lens looks out through the filter near the edges. More of an angle, more of a shift. You may get a color vignette that has less visible red towards the edges as the center reflection wavelength shifts away from infrared into the visible.