Infrared lens

Superb performance from the Laowa Shift line-up

Choosing an infrared lens is not as easy as it seems. Between the risks of hotspots, the drop in resolution at the edges of the image or even the appearance of colour fringes with certain IR filters, buying a modern lens to practice IR photography is often like a gamble.

In constant search of the best performance for my images, I regularly test new lenses in infrared in order to evaluate their abilities in a light domain that was not taken into account during their development. This article is about wide-angle, or even ultra-wide-angle lenses, since I am interested in the Laowa Shift line-up.

Let’s find out right now how the 20mm F/4 Zero-D Shift and the 15mm F/4.5 Zero-D Shift perfom in infrared photography!

A few words before we start

This test focuses on the Laowa 20mm F/4 Zero-D Shift and 15mm F/4.5 Zero-D Shift lenses. Regarding the 20mm F/4 Shift, a test model was lent to me by the brand so that I could evaluate its performance on medium format and as an infrared lens. The 15mm F/4.5 Shift, meanwhile, belongs to me: I bought it by my own.

The results presented come from rigorous field tests, and have not been modified for any commercial reason.

Handling and ergonomics

My opinion on the handling and ergonomics of the Laowa 20mm F/4 Zero-D Shift and the Laowa 15mm F/4.5 Zero-D Shift has not changed since my tests of these lenses on medium format. I therefore invite you to read the previous tests to discover all the good things I think about these two lenses:

Hotspot analysis

Hotspot is the most commonly defect observed of infrared lenses. Basically, it is a light spot of more or less intensity, accentuated by the closing of the diaphragm and generated by the multiple internal reflections of the infrared radiation in the lens and on the surface of the sensor. Kolari Vision website explains the phenomenon very well.

The presence of hotspots is increased by the selectivity of the infrared filter used: the phenomenon is more likely to be observed at the highest wavelengths.

To verify the presence of hotspot on the two lenses that interest us here, I photographed a white wall homogeneously lit at different apertures, from the largest to the smallest. I took the Canon 35mm F/2 IS USM as a reference lens, a model that I appreciate and have been using almost exclusively for almost 2 years.

The IR filter used is the 720nm from Kolari Vision. No corrections have been made except for the Canon 35mm F/2 lens profile. The test device is a full-spectrum defiltered Canon RP without AR coating.

The hotspot level of the Laowa 15mm F/4.5 Shift is almost imperceptible whatever the aperture is, which is a first one for me for an infrared lens.

The Laowa 20mm F/4 Shift suffers from a small, faint hotspot, visible from F/16.

Overall, these two lenses provide very good hotspot resistance, and if you use them at their optimal aperture of F/8 your images will be perfectly clean.

Internal infrared light leak

Some lenses integrate with electronics that emit a low level of infrared light signal. This is particularly the case with Canon’s new range of RF lenses, as studied by Kolari Vision.

Here we are in the presence of two manual lenses without any electronics: no leakage of infrared light is to be feared.

Sharpness analysis

The last parameter evaluated in this test is the sharpness delivered by these two lenses. Indeed, the performances observed in classic photography are rarely applicable to an infrared lens. The optical design and coatings have been designed to focus visible light, so a drop in performance is usually seen with an infrared lens, especially at shorter focal lengths.

In addition, optical performance at the edges of the image tends to degrade with IR filters that let through a lot of visible light, such as 595nm or 550nm filters. I tested the sharpness delivered by the Laowa 15mm F/4.5 Shift and the Laowa 20mm F/4 Shift with two different filters: the 720nm and the 550nm from Kolari Vision.

Let’s see what it is here. The images tested have simply received an RGB channel mixer: no sharpening has been applied.

The Laowa 20mm F/4 Shift delivers very good performance at F/8 over the entire image, at 720nm as well as at 550nm. This is the first time I have seen such good resolution in the corners and on the edges with a wide-angle infrared lens at this focal length.

The Laowa 15mm F/4.5 Shift also performs very well at 720nm: edges and corners remain detailed. On the other hand, at 550nm, the fringes and chromatic aberrations are very marked and the edges are no longer exploitable.

Looking for the best infrared lens with Laowa

In conclusion, Laowa offers us two lenses of its Shift line-up with very good performance in IR photography. If the 15mm F/4.5 Shift gives the best of it at 720nm and beyond, the 20mm F/4 Shift offer the best an infrared lens can, whatever the filter used.

Depending on your practice and your favorite IR filters, these two lenses have their place in your camera bag without hesitation.

To go further

Through my expertise in infrared photography, I offer a wide range of IR photo and video recording services for your scientific projects and artistic shootings.

Discover the relating offers by clicking on the following link :

I have built a pack of 7 LUTs dedicated with infrared processing.

These LUTs are optimised to work with Ligthroom Classic and deal with white balance, RGB channel mixer and precise adjustments with this software.

They also work well with other photo and video software.

If you want to use some of the pictures in this article for illustration or commercial purposes, contact me directly by presenting your needs and the desired types of use. I will get back to you as soon as possible with a suitable commercial offer.

Discover my other reviews

Laisser un commentaire

Votre adresse e-mail ne sera pas publiée.

Ce site utilise Akismet pour réduire les indésirables. En savoir plus sur comment les données de vos commentaires sont utilisées.