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View Full Version : Hot mirrors for FS100 in daylight



imag
05-25-2011, 05:29 PM
Do people think it's necessary to have a full Tiffen Hot Mirror filter for full daylight ND on this camera?

I have been looking around online and can't find convincing answers on this. I did find this cheat sheet: http://provideocoalition.com/index.php/aadams/story/ir_cheat_sheet_version_2/, which seems to indicate that the hot mirror is the only way to go for the F35 (vs. a standard IR filter).

Other stuff I find online says that IR issues are not a big concern nowadays, that modern chips have good IR filters.

Thoughts are welcome.

nyvz
05-25-2011, 08:11 PM
I think you may be reading that wrong. Tiffen T1 is probably the way to go for up to ND1.2 .

http://www.thelondonfiltercompany.com/filters/pdf/HD_Camera_Filter_Chart.pdf
http://www.tiffen.com/userimages/T1_IR_Charts_SS.pdf
http://en.wikipedia.org/wiki/File:Eyesensitivity.png

My understanding is that Sony/Arri tends to have quite a good IR filter, but as a "feature" was designed to see far-red more than is natural for the human eye, so you need to use a filter like the T1 or IRND for it since those cut starting at shorter wavelengths (about 650nm by the look of the Tiffen literature). Other cameras, like R1 or Phantom etc. have inadequate IR filters that trade image quality for sensitivity, and those are more likely to need a hot mirror since their contamination is actually IR, and the Tiffen T1 stop cutting IR above about 820nm.

imag
05-25-2011, 11:11 PM
Thanks so much - that was exactly the info I was looking for. I actually think I'm going to go with the IRNDs for full daylight, because I need ND 1.8 in midday sun, even with a pola.

My challenge now is to figure out the lowest cost most appropriate filter kit for the camera.

Anyway, thanks again - that's a huge help... and not getting hot mirrors saves me $80 per filter :)

nyvz
05-26-2011, 05:38 AM
And hot mirrors often give you discolored vignetting due to their dichroic coating so I'd stay away from them unless absolutely necessary anyway.