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IR CHROME:
KOLARI vs. ALIEXPRESS

An indepth comparison between both popular optical filters for infrared photography.

Kolari Vision IR Chrome vs Aliexpress aerochrome filter: Part I

With the rise of digital photography and the increasing popularity of infrared photography among both amateur and professional photographers, the market has seen the introduction of various dedicated filters for full-spectrum cameras.

One notable innovation is the Kolari Vision IR Chrome filter. Its release sparked enthusiasm — and even a sense of necessity — among photography enthusiasts to replicate its effects at a lower cost while achieving comparable results. Although Kolari Vision and Yann Philippe were far from the first to produce digital infrared photographs with striking red (or rather orange) foliage, this filter was the first I encountered that fuses both a blue glass and a heat absorber glass into a single ring to achieve this effect. Before its release in 2019, achieving this look in digital photography required stacking multiple glass filters or using Lee-type gels, as David Twede explains in his blog.

The Kolari Vision IR Chrome filter is relatively expensive. As an alternative, I developed a more affordable filter, now available on AliExpress. This version is composed of two separate 1mm-thick glass elements: QB19, a type of blue glass, and GRB3, a type of heat absorber. While slightly different in design from the Kolari Vision filter, this alternative delivers similar results, providing an accessible option for photographers exploring infrared photography.

Today, the alternative that originated from True Color Infrared has grown in popularity, with social media flooded by enthusiasts praising its excellent value for money. Let’s delve into a detailed comparison of the two filters to determine whether there is truly a significant difference between them.

technical aspects

In this article, I will delve into the technical aspects of both filters. In the following articles, I will present a detailed comparison of calorimetry based on the wavelengths analyzed in this article and their performance in the field.

Glass Quality and Construction Differences

The quality grades of these filters differ significantly: Kolari’s IR Chrome filter is rated as A Grade, while the Aliexpress filter falls between C and B Grade, contributing to the price disparity. Kolari’s filter features an anti-reflective coating that reduces flares and enhances light transmission, whereas The Crimson filter lacks such coating. Both filters are mounted in single rings; however, Kolari’s filter is a fused, dual-glass construction, while The Crimson filter comprises two stacked 1mm glass elements. Due to the thickness of the glass—2mm for The Crimson filter and approximately 2.5mm for Kolari’s filter—it can be challenging to use a lens cover with either.

wavelengths and graphs for kolari ir chrome and the crimson

I went to Universitat de Barcelona (UB) campus in 2022 to analyze my filters. Although the results were not the best, I published them in the UVP forums. For the sake of this article, I obtained the transmittance data for QB19 and GRB3 glasses at a 2mm thickness from Tangsinuo’s laboratory. I then calculated their 1mm transmittance using the formula T₂ = T₁^(d₂/d₁). Finally, I determined the stacked transmittance by multiplying the individual transmittances of QB19 and GRB3 at each wavelength. As a result, I can present here a theorised wavelength graph of The Crimson filter at 1:1 thickness of each QB19 and GRB3, which I consider to be fair and approximate to its wavelength according to my field tests. I also tried to analyse Kolari Vision IR Chrome by myself, but I prefer to publish the results of Zach Van Rijn about Kolari’s IR Chrome since they are much more accurate and detailed than mine.

The Crimson Kolari IR Chrome

Both filters exhibit similar transmission curves, though there are critical differences in their performance.

VISIBLE LIGHT TRANSMISSION (Vis)

In the visible spectrum, the Kolari Vision filter shows a transmission peak of 90–93% between 400nm and 460nm. This results in a distinct blue-to-turquoise hue. At 360nm, its light transmission drops to 72%, while at 550nm, it stands at just 33%. At 600nm, transmission decreases to a mere 10%, effectively cutting much of the yellow and orange wavelengths, though not entirely. The filter efficiently blocks red-spectrum wavelengths, transmitting only 8% at 700nm. Between 600nm and 700nm, transmission stabilizes around 6%, maintaining this value throughout the red spectrum.

In comparison, The Crimson filter demonstrates a transmission peak of 78-80% within the 360nm to 460nm range, resulting in a slightly bluer tone in its transmission band. At 600nm and 700nm, its light transmission measures 18%, while between these wavelengths, it allows around 11% to 13% of light to pass through.

infrared TRANSMISSION (ir & nir)

The Kolari Vision filter begins allowing NIR light beyond 720nm, with 16% transmission at this point and a peak of 23% at 760nm. Beyond this peak, transmission gradually declines to 12% at 850nm and further to just 6% at 1000nm.

In contrast, The Crimson filter permits 32% NIR light transmission at 720nm, reaching a peak of 45% at 760nm. However, its decline is steeper, dropping to 20% at 850nm, and falling to just about 4% at 1000nm.

Conclusion

It is indisputable that Kolari Vision IR Chrome glass quality is superior to The Crimson. Nonetheless, whether this quality difference is a major advantage or not, will come up again on the field tests.

On the other hand, both filters showcase similar wavelengths, although some key differences make each other perform differently. Expect The Crimson to offer duller vegetation due to a higher IR leakage and narrower bandwidth along the visible spectrum. At the same time, colour management directly from the camera could be tricky since more NIR light entering the sensor could overload all channels, demanding more green to be added by the software. Green directly affects the vegetation, as a result, certain sensors could result in yellowish tones in vegetation instead of orange or red tones. Kolari’s IR Chrome, on the contrary, could lead to cold-looking images and inaccurate white and grey tones due to the low amounts of yellow, red and low IR bandpass.

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