How to Film in the Ultraviolet

Filming in UV requires removing a filter, getting UV-transparent lenses and getting a good filter to block all other light.

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I've always been fascinated to film in the UV because it reveals to us a world that is always there but invisible to us. Most objects are not surprising but skin, dish detergent, flowers, tonic water, and optical filters are all very different in the UV part of the spectrum.

The UV-pass filter I used was the Baader-U. The other filter was the ZWB1 that you'd have to use in conjunction with an infrared blocker. I have one around here somewhere but not sure exactly where.

[estebanfortu]

It would be great to see a video of the infra red spectrum

[eyeinvisible]

A few things to consider:
Fast lenses do not always translate into good UV lenses. Even with an aperture of ƒ/0.95, the modern coatings on most lenses filter out a lot of UV.
Also, it's not enough to let in lots of light with a fast lens: the lens' optical scheme must allow for focusing in the UV spectrum, which is difficult, as the lens is designed to focus visible light. This explains the "glow" around the flowers in the video. Even older glass lenses aren't that good at transmitting UV - the best UV lenses are made from quartz, which does not block UV, and can focus UV light better than glass.
Whilst the Baader-U is one of the best UV passing filters, it is very expensive, and the filter is non-standard size, so a step-up ring is required to attach it to a camera lens.
Also, the Baader-U is a dichroic filter, which works by interference, rather than by absorption. The angle of incidence is therefore important, meaning that at wider angles, discolouration occurs at the periphery of the image. Conversely, a ZWB/UG filter stacked with an IR cut filter works by absorption, so the angle of incidence is not a factor.
Since UV is not a colour - it's monochrome - removing the bayer filter from the sensor can also help increase UV sensitivity. Of course, you would only do that with a UV-dedicated converted camera.

[SaraMakesArt]

So to shoot in the ultraviolet, you need to take the ultraviolet blocker off your camera, (this is the first I've heard of this) and you need an additional filter to block out the infrared. The main things I learned from this video is how little ultraviolet light there is and how much dedication Derek has in making videos.

[PaulPaulPaulson]

You can get those filters that pass all wavelength of light at the same stores that sell wifi cables and wifi enhancer spray.

[sjeses]

I love doing infrared photography. My old dslr doesn't have it's filter removed however, so I need multiple second exposures even in full daylight. This has an added esthetic benefit for me: it gives a soft ghostly feel to them because everything that moves gets smoothed or becomes ethereal

[marsgal]

I've played with infrared photography, but never ultraviolet. The same optical issues you discuss.

You used to be able to get colour IR slide film from Kodak which shifted everything down a notch with near infrared rendered as red. I thought of the results as "Barbie World", green plants rendered in red and blue (IR -> red, green -> blue), a fuchsia world.

The dreamy black and white moonlit look is much more my speed...

[lescarneiro]

Never wonder how difficult would be to set up this video, now I do, what a challenge! Congratulations for the perseverance, focus and great work put on that video!

[NickBoone]

The spectral response of the camera will also be having a massive effect on the amount of UV you can actually capture. Standard silicon CMOS sensors like those in digital cameras are tuned to be responsive to only visible light. You'll get very little light being picked up by the sensor outside of the visible wavelengths, I'm kind of surprised you can see that much.

[besmart]

Hey Derek, remember who ELSE has a full spectrum camera? Call me, dude 🤓

[terrymac]

Don’t forget the quantum efficiency is lower at the extremes of the cmos bandwidth which also adds the extra attenuation about 3 stops, normally a wide open chip will work 280nM to 1180nM, when the filter is used for visible light it will generally see 380 though 720nM.

[KCMDWannabe]

Hey Derek! A great thing you can shoot with infrared is nebulae! Particularly emission nebulae. I know you need a telescope setup to do it but I'm sure there is plenty of amateur astronomy groups happy to lend a scope.

[billthetraveler]

Thank you for saving a bunch of money 💵. I have a travel zoom camera that I removed the UV/IR blocking filter. It works great for IR. I thought that since my CMOS sensor is open to full spectrum I would just buy a filter for blocking out visible and IR. There get really pricey and as you mentioned, in UV light it is actually dark outside. Thank you for the terrific content.

[mathewalex]

Derek, you are the champion of physics for the common YouTube audience and an excellent film maker. I think that it would be awesome if do a dedicated video about modern cameras, after all you are great film maker. It can be done like this in Veritasium2, with you chit chatting in front of us.

[dazextralarge]

I wish I could buy cameras and lenses here in Brazil without having to sell my house.

[cavalrycome]

Do a video on why many (but not all) leaves are so reflective in the near infrared (the so-called 'wood effect'). Conifers appear to be an exception.

[lukasbrucas]

Yes, please make a video about the world in infrared!

[Ynook]

I hope I am not thinking about this in a wrong way, but the colors in the UV light film are still perceived through the visible light spectrum by the observer. I mean, there will still be nuances of grey and other colors. We still don't know what the 'color' UV light looks like. Am I wrong?

[Bugkiller]

I.m very excited to see how can you shoot on infrared using that camera !

[braindesigns]

Great video! I have been trying to make a UV pass filter (for video), with alternate materials. Infrared is no problem using Floppy Disc IR pass filter in combination with a Night Vision camera that actually switches to an uncoated hot mirror, and amplifies the IR signal, and also has IR bulbs. I also created an Infrared and Ultraviolet spotlight to help with lighting in these tests. After a lot of reading I found (and have tested) that Black & white exposed & developed film will block IR (due to Silver) and pass UV. So I made Lithograph filter to pass UV (hopefully) and it does indeed block IR. I have 2 major issues: 1.) the extremely low UV light available. Your video really helped clarify that there is just not enough UV present. I did try aiming my UV spotlight directly at the lens and in the daytime, and saw nothing (now I see it may be from IR contamination), but at night, I could actually see only the pure UV light although it was very faint. Interestingly enough, a green laser seemed to penetrate the filter, but it is possible the laser just illuminated the film itself. 2.) The camera I am using switches to a filter that allows IR (but is it still coated to block most UV?) and also the sensors amplify IR (but do they discriminate UV?). One last idea, is to use an old disposable 35mm point & shoot camera with the clear plastic (full spectrum lens) with a small uv pass, and visible and IR blocking filters taped on...but I am pretty sure the exposure time will not be long enough. Maybe I can just use an IR blocking filter at night (with amplified Night Vision / uncoated hot mirror, and free from visible and much IR light because it is night) to film powerlines, looking for a little arcing. At least I may have a better chance at night (this is what I got from your video). Also, would filming the sun in daylight hours be a sufficient test to see if the UV pass is allowing enough UV through? Very cool either way! Thanks your video was very helpful, especially after searching 100's of pages for these answers for the last few months.

[Marcos-bovi]

You can see some degree of fluorescence in the trees. The one on the right is dark as it absorbs the UV light. The one on the left, with full spectrum, is shinier than the center trees under only visible light.