1. What is ultraviolet photography?
Ultraviolet photography (UV photography ) is a new way to realize unique pictures by photographing near ultraviolet spectrum, below 380nm. This part of the electromagnetic spectrum is invisible to human eyes. Camera sensors can be sensitive to it once they are modified. It is the same for infrared photography.
Ultraviolet impacts the environment a totally different way than infrared. we can use UV photography for artistic photography (macro, portrait, landscape) as well as for analytic photography (dermatologic and forensic analysis).
2. What do I need for UV photography?
Ultraviolet photography requires some modifications to the camera like infrared photography. The only way to make the camera sensitive to ultraviolet spectrum is to convert the camera to a full-spectrum conversion. Due to, when using the corresponding filters, it will allow you to do both ultraviolet and infrared photography.
If you already have a full-spectrum camera, then you will not need any extra modification to do ultraviolet photography.
The necessity of a full-spectrum camera implies the use of a filter to put on the front of the lens. The UV transmitting bandpass filter made by Kolari Vision provides the best filter solution in term of coating, transmission diagram purity and building, offering well contrasted and detailed pictures.
Modern lenses have an anti-UV coating on their front element. Because of that ultraviolet photography requires specific lenses letting UV light pass through their optical elements. The best UV-capable lenses are also the most expensive: quartz lenses. These lenses are made of quartz and are dedicated to scientific use. Fortunately, far less expensive solutions exist lenses with few (or even no) anti-UV coating and a small number of optical elements. We can divide these lenses into 3 categories:
- Entry level lenses
- Old lenses
- Enlarging lenses
3. How do I do UV photography?
Focus and composition:
Use a modified camera offering live view to compose your pictures and focus on your subjects, as for infrared photography. With live view, you can directly compose and focus thanks to the sensitivity of the sensor for ultraviolet light.
If your modified camera does not offer live view, you will have to follow these steps:
- Remove the UV transmitting bandpass filter from your lens
- Compose your picture and focus on your subject in visible light
- Disable the AF of the lens
- Put on the UV transmitting bandpass filter
Some UV-capable lenses suffer from focus shifting in ultraviolet compared with visible focusing. Using this method, you will have to take this parameter into account.
Warning! Safety information: NEVER put your eye in the viewfinder when the UV transmitting bandpass filter is put on the lens. It could seriously damage your eye. Also, NEVER look through the UV bandpass filter itself.
Before shooting, we have to use a grey chart so we have perfect white balance. This way, the sensor will be calibrated to offer perfect hue and contrast without a color cast. Do not forget to shoot RAW!
4. How to process UV photography?
Ultraviolet photography does not require advanced skills in digital processing. It is enough a simple white balance done on a grey chart. This way, you will obtain a subtle purple/blue hue on your subjects.
Therefore, you can also do a classic black and white processing to avoid this hue. It will give a silver effect and a specific distribution of contrast.
For static subjects, you can mix visible and ultraviolet shots to mix ultraviolet contrast with visible colors. This technic only works with static subjects. You have to take the same 2 pictures of your subject. One picture in the ultraviolet and one classic in visible light (with a hot mirror filter).
Then in Photoshop (or other software using layers), put the visible shot on the ultraviolet shot and use “color” mode on the top layer (shot with visible colors).
5. UV picture examples with Canon 6D FS and different filters: