In this illustrative guide, I am going to tell you all about ‘black light photography’. Black light is invisible ultraviolet light that allows fluorescent objects to radiate. In a more prosaic way, we are talking about invisible light here, for example that used in nightclubs to illuminate any light clothing with ultraviolet.
A black light emits ultraviolet, this radiation highlighted in 1802 by the German physicist Johann Wilhelm Ritter. He realized that beyond violet, ultraviolet rays were able to oxidize silver chloride. It took several decades to understand that ultraviolet (visible), and thermal (infrared or invisible) rays formed a continuum constituting the spectrum of optical radiation.
The best-controlled way to produce ultraviolet black light is to electrically discharge mercury vapors. For more than 80 years, this is indeed the best technique used in fluorescent tubes.
To create a black light, you have to filter the light by letting the UV pass and eliminating the visible, which is the complete opposite of ordinary glass. The American physicist Robert Williams Wood invented at the beginning of the 20th century a glass with these properties. Used on lamps during the First World War, this invention made it possible to communicate at night with the invisible ultraviolet signal.
In practice, Wood’s glass contains a lot of nickel oxide. It is logically practically black in appearance. Only the ends of the visible are transmitted when the lamp is on. In particular, the 405 nm spectral line of mercury gives light a violet color. Slightly less effective but much easier to use than Wood’s glass, the envelopes of black light lamps currently on the market consist of a coating deposited on ordinary glass.
But to be considered a black light, the lamp must emit less energetic UV, called UV-A from 315 to 400 nm. It is therefore necessary to transform the UV-C into UV-A by fluorescence. While current fluorescent tubes use three types of phosphors which, when excited by the spectral line at 254 nm, emit in red, green and blue, black light fluorescent lamps only use a single phosphor emitting in the ‘UV-A, typically around 370 nm.
An alternative is to use mercury lamps, but this time at high pressure. No more need for phosphors since such lamps emits directly in a spectral band between 350-375 nm.
Even simpler and without using a wood filter, it is possible to emit UV directly with LEDs. The further we go towards distant UV, the more the technology is still emerging and the more expensive the UV lamp is. But for black light, LED lamps emitting around 390 nm are now marketed at competitive prices. You can buy these black light equipment on amazon for $20 to $50 price range. Here is the link of 32.8 ft LED UV Strip Kit.
Black light also makes it possible to reveal security patterns printed with invisible inks on banknotes or identity cards, or even to highlight dermatological pathologies.
Characteristics of Digital Black Light Photography
With black light photography, the photographer determines what cannot and what cannot be seen. The staging is performed using fluorescent tools that become visible under black light.
The wide range of tools allows for a spectacular, multi-colored presentation that you won’t find anywhere else.
The Necessary Conditions for Black Light Photography
Thanks to the relatively dark ambience and backlighting you can use a camera that takes low digital noise photos in higher ISO ranges. This helps ensure that images meet your quality standards and avoid digital noise in dark areas.
In fact, you are using a fast lens which allows for low aperture values. This gives you a wider aperture, better light exposure and shorter exposure times.
As the name suggests, the most important element in black light photography is the backlight itself. Depending on your goals, traditional UV tubes or special backlight lamps can be used as light sources. For selective lighting, we recommend that you use backlight torches that can be purchased at low cost.
To create beautiful colorful images in black light photography you will need fluorescent materials. There are online stores that specialize in blacklight accessories and the work of other photographers is a good source of inspiration and offers a variety of combinations. The offer is rich, makeup or soap bubbles for black light for example.
You may also like to read: Lighting in Photography: An Illustrative Guide for Beginners
Find the Right Place to Take a Black Light Photo
The photo shoot should take place in a controllable environment. Any interference, such as incident light, can affect the success of the session and should therefore be avoided. A session indoors in the evening or at night is generally preferable because you will not be disturbed. All windows and doors should be covered in black for the duration of the shoot and it is best to use a black background when taking pictures.
Even photos taken outdoors at night can still give fascinating results. To avoid the influence of bothersome light sources such as lanterns or moonlight, instead take your photos in a rural environment without light pollution. Black light spots are very practical for outdoor photo shoots because they are mobile and run-on battery power.
How to Use Black Light Safely
To protect your eyes, avoid direct contact with sources of black light. Photography in dark environments can also be tiring, even grueling over time, and you should avoid staring into your camera’s viewfinder for extended periods of time. We recommend that you use the “Live View” function of your camera to view the composition of the image on a larger display.
Manual mode photography: full control over ISO, aperture and exposure time.
Select your camera’s manual mode, the only way to set ISO, aperture and exposure time values.
The ISO value should be set according to the brightness of black lights used and indirect light from fluorescent elements. If a lot of light tools and black lights are used, a low ISO value may be selected. If on the other hand you limit yourself to using a few light sources, you will not be able to avoid using higher ISO values (up to the highest four-digit values). The maximum also depends on the camera model to avoid unpleasant digital noise. Use it in test shots with favorable ISO values.
The aperture value should be individually adjusted according to the subjects and the desired depth of field. If you want to shoot only one subject and make it stand out against the background, select a low aperture value. If you want to show two or more subjects clearly, experiment with larger aperture values. But since the size of the aperture also determines the amount of incident light it should also be selected according to the mood created by the lighting in your environment.
The exposure time should be adjusted to ensure that the subject is always sharp and visible. The exposure time required depends on the subject, whether it is dynamic or static. To avoid shaky or blurry images, choose an exposure time short enough for dynamic subjects, starting at around 1/50th of a second. It is recommended to use a tripod when taking photos of static subjects, and long exposure times (1/5th of a second for example) can give sharp results; therefore, prefer parameters such as a higher aperture value for a lower ISO value.
For better color reproduction, it is best to intentionally underexpose the image slightly. Underexposure will make fluorescent colors stand out more intensely.
RAW Files: The Basis for Further Image Processing
When possible, save images in RAW format. This type of file will take up more space on your SD card but will save considerably more information per image and you will be able to edit RAW files much more comprehensively than JPEG images.
To better emphasize and enhance vivid colors, it is recommended to use image processing programs such as Adobe Lightroom with which you can change the color of the image afterwards by adjusting the hue and saturation. Do not hesitate to experiment, and multiply the interesting results.