Can You Use Anti-reflective Coat On Glass To Use Ir Camera Indoors

Lately, at that place has been an increasing interest of Anti-Reflection (AR) coatings in the infrared photography community.

I visitor has boldly stated that their internal AR coated IR filters tin reduce or even eliminate lens hotspots. To be fair, years ago we too experimented with AR coatings on internal filters but for a different purpose, to improve the low-cal sensitivity by having more calorie-free pass through the filter instead of being reflected off of it's surface. The end goal beingness shorter exposure times, not hotspot reduction. More nearly that beneath.

Since the competitor's claims accept been making enough waves that our customers have been request us about the validity of AR coatings for this purpose we decided to put information technology to the examination. The goal of the tests was to decide conclusively whether or not internal Infrared filters with AR coatings offered whatever advantage for hotspots, every bit is claimed by the competitor. The methods and results are to follow only first a quick refresher on IR hotspots:

IR Hotspots can appear at the center of an image and have a circular area that is unremarkably lighter and of less contrast, occasionally also having some color shift. These hotspots tend to exist less obvious at a wide discontinuity and progressively become worse as yous stop downwards. The just skilful solution is to use lenses that don't suffer from this trouble. Some people find they can reduce the event in post processing software like Photoshop, but this is much more difficult and would need to be washed to every image, whereas changing lenses solves the problem instantly for all images captured.

Lenses are designed for normal, visible light photography and when used for a purpose for which they were not designed, bug can arise, similar the dreaded IR hotspot. Unfortunately, the truthful crusade of this issue isn't entirely known as multiple factors could exist playing a contributing role but the consensus is that the upshot is caused by internal reflections of IR lite within the lens itself, be it from the coating on the lens barrel beingness IR cogitating or IR light interaction between the lens elements that make up the lens or the coatings on the lens elements themselves or maybe a combination of all of these. Regardless of the cause, we know definitively that the issue occurs within the lens itself.

When we heard of claims being made that AR coatings on internal infrared filters that are installed over the sensor inside the photographic camera can reduce or eliminate IR hotspots, we were naturally quite skeptical. The claims made no sense to us, why would more light reaching the sensor assist in spots that are already formed in the lens BEFORE reaching the sensor?Even so,

So we set out to test the claims. For our test, we used three Sony A6000 cameras:

The first camera was converted with our uncoated Deep BW IR (830nm) filter.
The 2nd camera was converted with our ain AR coated Deep BW IR (830nm) filter, we used the best of the stock we have.
The tertiary camera was purchased direct from and converted by the competitor with their AR coated 850nm filter.

For the test, we took the same shot with all three cameras with a serial of both Sony Eastward/Fe lenses known to take hot spots and also with several Catechism lenses used with an adapter.

The following lenses were tested as they are known to have hotspots:

Sony 16-35mm f4, Sony 16-50mm f3.v-5.6 (kit lens), Sony 16-70mm f4, Sony 24-70mm f2.8, Canon 16-35mm f2.8 Two, Canon 24-70mm f2.8 II, Catechism 50mm f1.iv

These two sets of images are from all iii of our cameras with the Canon 50mm f1.iv lens.

The outset gear up of images are with the same exact setting directly out of the camera, the second prepare are the aforementioned images with exposure adjusted to look identical.

Life Pixel'southward uncoated filter

Canon 50mm f1.4 lens

50mm i/30sec f22

Our AR coated filter

Canon 50mm f1.four lens

50mm one/30sec f22

Competitor's "hotspot reducing AR coating"

Canon 50mm f1.iv lens

50mm 1/30sec f22

Life Pixel's uncoated filter

Canon 50mm f1.4 lens

50mm 1/30sec f22 – exposure adapted

Our AR coated filter

Canon 50mm f1.4 lens

50mm 1/30sec f22 – exposure adjusted

Competitor's "hotspot reducing AR blanket"

Catechism 50mm f1.4 lens

50mm 1/30sec f22 – exposure adjusted

As you can encounter from the exam images, nosotros were blown away to find that our uncoated filter really looked meliorate than both our AR coated filter and the competitor'due south AR coated filter. It was very shocking to see that the AR coating was making the hot spot worse and more exasperated. We also discovered that the coating was somehow reducing light sensitivity. We are certain that we took the aforementioned shot with all 3 cameras with the aforementioned aperture, ISO, and shutter speed seconds autonomously on the aforementioned tripod and light remained consequent as it was a clear sunny day and yet all the AR coated images were noticeably darker. Then to conclude, our testing showed that AR coatings actually did non help with IR hotspots in whatsoever way and actually fabricated the hotspots worse likewise as losing pregnant amount of light.

We are confident in the tests performed and are glad to finally have some concrete data for our customers to review and to help them brand informed decisions almost their IR camera conversion options. While we volition always continue to seek materials and methods to improve our conversions wherever possible, including means to reduce hot spots, LifePixel volition not exist offer internal AR coated filters for the purpose of reducing IR hotspots as it does not work. Based on the test results, the data is just non there in support of these claims and frankly seems to exist merely another gimmick aimed at profit gains.

Below we will leave more than examples from our testing with all lenses, nosotros will follow the same pattern to do the first prepare of images directly out of the camera and the second set with exposures adjusted. Left to correct: our uncoated filter, our AR coated filter, competitor's coated filter.