EX1/EX3 IR Filter Shoot-Out
The EX1/EX3 built-in Hot Mirrors suck. Or do they? One way to find out...
By Art Adams | February 26, 2009
The Sony EX1 and EX3 are great cameras for the price, but they do have some fairly obvious issues with IR/far red when used with neutral density filters in front of the lens. This test taught me far more, though, than just what filters to use to eliminate a color problem on these cameras: I learned never to make assumptions about how a piece of equipment works until I've tested all possible options.
I'm not going to recap my testing procedures or the physics behind how the different filters work. You can find those details in my F35 and RED IR articles. I've gotten a lot of requests for an EX1/EX3 IR article, and as I've previously explained the basics this article is going to focus solely on results.
Here's what the test setup looked like, without any on-lens filtration:
The setup consists of a DSC Labs Chroma Du Monde chart, the Chroma Du Monde polyester chart bag as an IR/far red reflector, and a slate.
Here's the same setup with Schneider Optics ND 1.2 filters in front of the lens:
As I've explained before, all heavy ND filters show some color shifts because it's impossible to make a dye that is perfectly neutral. Some ND filters go warm and others cool. In this case the Schneider filters add a reddish hue, which I've attempted to correct out in Photoshop. A simple white balance is enough to get rid of this hue in camera, but I chose to do it in post in order to observe the various filters' color shifts.
In spite of white, black and gray balancing in Photoshop, the black DSC chart bag has turned a bright maroon color with four stops of ND in front of the lens--brighter than I've seen on any other camera I've tested.
The first time I looked at a black cotton shirt under tungsten light on an EX1 it turned bright maroon even without ND. Between that experience, and seeing how much red I saw with some ND in front of the lens, I figured that the built-in Hot Mirror on these cameras was either very bad or nonexistent. I was wrong, but I wouldn't figure that out until later. Read on...
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