F35 IR Filter Shoot-Out
We test IR filters from three major manufacturers to see which does what on the F35
By Art Adams | February 18, 2009
Technically the Sony F35 isn't sensitive to infrared, but it is sensitive to far red. The difference will save you a lot of money on filters.
Before we start, it might be a good idea to take a look at this article to refresh your memory as to where in the spectrum IR/far red filters cut, and why they become important under certain conditions.
The methodology for this test was similar to the RED test: each shot was recorded digitally, although in this case to a Panasonic HPM-110 P2 deck in AVC-Intra fed via the camera's HD-SDI port. I exported a frame from each shot into Photoshop and color corrected it in the same way I described in the RED Hot Mirror shoot-out article.
In the center is a DSC Chroma Du Monde chart lit with two tungsten Arri 1k open-face lights. Behind the slate is the chart's polyester case, which is an excellent source of reflected IR/far red.
The F35 is so sensitive that we were able to achieve a stop of T22, using Arri/Zeiss Ultra Primes and no filtration.
For several of the filters we did a flat field test in order to detect off-angle color fringing due to dichroic coatings:
This is what the 16mm Ultra Prime looked like at T8:
This lens shows some vignetting at certain T-stops so keep that in mind when looking at the flat field tests. What we're looking for are color shifts around the edges of the frame, not brightness shifts.
On to the tests...
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