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IR CHROME:
KOLARI vs. ALIEXPRESS

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

Kolari ir chrome VS. Aliexpress Aerochrome filters: Part 2

In my previous article, I presented the main technical aspects, similarities and differences between the Kolari IR Chrome filter and the Aliexpress Aerochrome Filter.

colorimetric analysis

The differences between these two filters reveal two closely matched options in terms of light transmission and colorimetry. However, the most striking divergence lies in their handling of NIR (near-infrared) light.

The Crimson Filter produces images with less contrast between yellow, orange, and red tones. By transmitting less blue light and allowing significantly more infrared light in the 720–850nm range, this filter creates a warmer overall tone, especially noticeable on surfaces that reflect IR light. Additionally, in some sensors, the Crimson Filter may lean more toward the yellow spectrum. This tendency arises because the camera’s software might interpret the combination of blue from the filter and red from the NIR as magenta, and compensate by adding green. When green is added to the red of foliage, it produces yellow according to the additive RGB color model. This tendency is normally well controlled by applying manual WB instead of grey-card WB. However, in my Fuji X-Trans IV sensor, both methods work perfectly fine.

In contrast, the Kolari Filter produces cooler overall images by effectively controlling the amount of NIR light reaching the sensor. This control minimizes the dominance of magenta tones typically caused by a combination of blue and IR light. As a result, images captured with this filter tend to show less yellow dominance. Vegetation, in particular, often shifts toward orange tones. This shift occurs because the camera continues to compensate for the magenta bias in IR and blue light by adding a degree of green. The interplay of red from the IR and green compensation results in orange hues, following the principles of additive RGB.

Visual Spectrum Test

These images were taken with a VIS-modified camera (Fuji X-T3) using a white sheet of paper and 5500ºK light. The results reflect how the camera perceives each filter under visual spectrum conditions. Each image has been balanced to 0EV to ensure consistent exposure, allowing for a clear comparison of the tonal and colorimetric differences.

Kolari Vision
IR Chrome
True Color Infrared
The Crimson

Full Spectrum Light Test (IR + ViS)

The second set of images was taken under sunlight on a white sheet of paper. The camera was set to a white balance of 5500ºK to simulate natural light conditions. No additional color correction or balancing was applied to the images, providing an unaltered view of how each filter influences the captured colors under real-world settings.

Kolari Vision
IR Chrome
True Color Infrared
The Crimson

Note the differences between the pure VIS and IR + VIS. While both filters look close on the visual spectrum, it’s obvious that The Crimson looks more towards purple on the VIS + IR test. This fact is important since it explains why The Crimson tends to render deeper blue skies, while the Kolari Vision IR Chrome lies on the turquoise side.

white balance

The white balance of both filters reveals significant differences. During my tests, the Kolari IR Chrome filter could not achieve a true white balance. In Lightroom, the Auto WB values applied are 50,000ºK with an adjustment of 10 points toward green. Meanwhile, The Crimson filter falls between 14,000ºK and 15,000ºK, with a much stronger green adjustment of 61 points.

Kolari Vision
IR Chrome
True Color Infrared
The Crimson

These differences stem from the key characteristics of each filter, as seen in previous tests. The Crimson filter allows more IR light to pass through, requiring compensation for the excess IR light by adjusting heavily toward green. Kolari’s filter, on the other hand, uses a stronger blue tone, which is also slightly greener (as shown in the previous graph), to offset the excess IR light. This helps balance the excess red and magenta inherent to IR light, reducing the need for additional green adjustments during post-processing.

Conclusion

The colorimetric data presented in this analysis highlights key differences in how the Kolari IR Chrome and The Crimson filters manage infrared light and white balance. The Kolari IR Chrome filter demonstrates a noticeable bluish cast, even after proper white balance adjustments. This design choice helps counteract the red and magenta dominance characteristic of IR light, with its stronger and slightly greenish blue tones reducing the need for extensive green compensation during post-processing. However, in field conditions, this can sometimes result in colder tones or a residual blue cast, requiring advanced knowledge to create accurate color profiles using post-processing software.

On the other hand, The Crimson filter, with its higher IR light transmission, necessitates more substantial adjustments toward green in both white balance and post-processing to achieve a balanced color spectrum. While the tests in this analysis show that The Crimson generally handles color better, field conditions might reveal red casts on white or grey surfaces due to excessive IR light leakage. As a result, performing a proper white balance on location with a grey card or making precise adjustments during post-processing is crucial for optimal results.

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