Hot Mirror/IRND/Mirror ND Filter Matrix [Parts 1-4]

[Evin Grant]

In the real world test the IRND seemed to have a more noticeable effect. However it was still subtle, I don't think it's fraud but I don't think that product has much future either.

[Chris Nuzzaco]

I wonder if there is a way of maybe building this IR filtering into the lenses rear elements....

[Evin Grant]

So, after much poking and prodding we're finally at the end. But before we come to the conclusion we have one more test to endure...

Tungsten.
As you many of you have found out shooting the Red One with tungsten light can be a challenge. You probably have figured out by now that one factor is the blue channel being starved of light, but another is the high IR content of most Tungsten sources. Here we investigate the effect of our three Hot Mirror options in this environment. IT is important to not that It is unusual to use ND filter when using tungsten so I have omitted the Pancho and IRND filters from this test.

The top 4 frames are uncorrected based on the "Control" filter less frame.
The lower 4 frames are individual corrections for reference.

Here you an see the same characteristic color shifts we saw in the daylight test. The Schneider is showing it's strenght in this test. In fact I might go as far as to say the Shcneider seems as it was designed with Tungsten in mind. The Rosco and Tiffen are neck in neck here with an edge to the Rosco.


Although you would usually not use an ND filter when shooting in a controlled tungsten light environment I though it useful to demonstrate the effects of the IR and the filtration. ND filters do this by increasing the ratio of IR light to visible, thus creating an IR pass filter. You can see clearly here that at 2 stops less ND than in our outdoor test the IR is overwhelming the control scene. Again the Schneider seems the best suited to the tungsten with the Tiffen now a little ahead of the Rosco.

[Evin Grant]

Conclusion...

Finally, after a month of pleading and begging all the filter Co. to provide samples, and three days of testing, what have we learned?

First off the failures...
I truly believe that, although the Schneider True-Cut IR lives up to it's name, especially under tungsten light, the off axis color shifting issues make it useless on any lens shorter than 32mm. For me that rules it out.
Also the Tiffen NDIR filters do not seem to me to add much to the equation. Although they seem to attenuate a little farther into the red spectrum than the standard filters they are not capable of competing with either the Panchros or a Hot Mirror + ND together.

Not a loser but...
The Tiffen Hot Mirror/IRND 1.2 combo filter does the job but not any better than separate filters and arguably with more color shift. It also is the most expensive single filter with a list price of $600 ($450 street). This make it a specialty Item in my mind, really only suited to those who have to use clip on matteboxes and are very limited in filter trays. Although the Panchro 1.2 ND accomplishes everything this filter does for a little over 1/2 the price.

The Winners...
I'm going to address these solutions by price range because they all get the job done adequately but have varying degrees of cost and connivence associated with them.

Beer budget: Rosco TruColor
The Rosco has arguably the best formula for cutting IR. There is no doubt it works but the single exposed, un-hardened coating makes it a fragile butterfly in the wilds of production. Be careful and it may serve you well, and at as low as $130 there's little to argue about price.

Wine budget: Tiffen Hot Mirror
The Tiffen is more expensive than the Rosco because it's a sandwiched, highly durable design. It also has the best off axis color performance of all the Hot Mirrors while still getting the job done. If you already own a complete ND set (Regardless of brand) this will work great for you provided you have enough filter trays to accommodate two filters and preferably a 4.5" or 138mm Polarizer.

Champagne:Pancro Mirrored IRND set
The Pancros are my top pick for one very important reason...
They maintain the original character of the sensor regardless of density. Because they reflect exactly as much IR as they do visible light you can use them singly or in conjunction with other filters or Polarizers and the image is the same color and character as if you weren't using any ND at all. They also have no discernible color shift. If you have yet to purchase an ND set this is the way to go. They are expensive but not much more than a set of competing regular NDs (About $350 each filter). If you really want to cover your bases pick up a set of Panchro filters for outdoor use and a Tiffen or Rosco Hot Mirror for tungsten shooting.

Reflections on reflections...
All the Hot Mirror and Pancro filters essentially become mirrors once the filters are in the matte box. They all reflect enough to catch the talents eye or possibly reflect a bright light into the scene. Be aware and try to use common sense and good light discipline and you'll do fine. Unfortunately if your subject just can't take his eyes off himself in your filter, call his agent.

[Damon Meledones]

Do you have an image of this test scene taken with a digital SLR or other camera?

[Greg M]

why did you omit the Pancros in this test?

[Evin Grant]

The conclusion is above now.

why did you omit the Pancros in this test?

I thought about it, but since there is not really any reason to use ND under tungsten light I omitted them as well as the IRNDs. The second set is really just demonstrative. Also from my tests and experience the Pancro filters cut exactly as much IR as visible, so there would be no real difference from the control in the first set.

[Evin Grant]

Do you have an image of this test scene taken with a digital SLR or other camera?

No, why do you ask?
The light used was a 650W Lowel Fren-L, hard, right over camera.

[Greg M]

Thanks again, great review!!

Fortunately I chose the best option.

[Frank Weeks]

Conclusion...

Well done.

and thanks again for your time and creative eye.