If you’re planning on choosing a type of lighting for your imaging studio, there are two main features that you’ll likely be considering. The first feature is color reproduction, or how closely does the light source match the color and spectral characteristics of natural daylight. We see two metrics on advertisements or spec sheets that measure the ability of a light to reproduce an object’s colors when compared to natural daylight: Color Rendering Index (CRI) and Color Quality Score (CQS). Both of these metrics are based on a scale from 0-100, with 100 being the best possible result. Without getting too into the weeds on each metric, the main difference between the two is that CQS is on its way to replacing CRI as the standard for evaluating the color quality of lights (especially LEDs) since it samples a wider, brighter, and more saturated color gamut than CRI. In general, if you only see CRI on a speec sheet, you should take it with a grain of salt as it’s an older, less strict and easier to “cheat” metric of color quality.
The second feature is flexibility. If you approach object photography with a more creative style—or if you light every object differently—chances are you’ll need a lighting system that accepts a variety of modifiers like soft boxes, barn doors, etc. Need to tone down the highlights on a glossy surface? Perhaps choosing a soft box over a reflector will do the trick. Need to add a little fill in the opening of a vase? Try grabbing a grid. These types of lighting techniques are generally used to photograph three-dimensional objects to describe and give them life (not to be confused with 3-D, computational photography), whereas more flat, balanced light would be used to photograph “2-D” objects or works on paper. Homogeneous illumination across the entirety of the object ensures that the digital image reproduces the object as it would look in full sunlight.
Generally speaking, we want to choose a light with a CQS of at least 95 when doing color critical photography such as artwork reproduction. Even high-quality household lights may boast promising CRI scores, but rarely have as high of a CQS. It goes without saying that household lighting is not the choice for artwork reproduction. Museum and gallery lighting is designed to have much greater color reproduction qualities than household lighting so that we’re able to take in the colors of the original artwork in full when viewing them up close in a gallery. The attribute that both of these types of lights lack is flexibility—the lights were designed for, more or less, a single purpose.
Good quality photo studio lighting like those available from Broncolor and Profoto also tend to have excellent color reproduction qualities, but they benefit from an enormous amount of flexibility. Studio strobes accept a wide variety of modifiers for descriptive light shaping. They also emit enough light to overpower overhead lights—removing the need to work in dimly lit rooms, especially when paired with a leaf-shutter lens syncing at high shutter speeds.
Sometimes strobes may not be the clear choice after considering price, parts & maintenance, or operator comfort (i.e. eye fatigue). Therefore, we should consider where two different continuous light sources fit into the equation: The DT Photon series and the Broncolor LED F160.
When it comes to color reproduction, the DT Photon series is the only lighting designed specifically for cultural heritage imaging and color reproduction. With a CRI & CQS of 98, smooth spectral output, and conservation-friendly UV-filtration & operating temperature, the DT Photon series is the clear choice for color critical photography and proofing.
The Photon’s main flexibility feature is its ability to double as an illumination source for transmissive materials. Used with the DT Photon SmartController, the Photon lights can even simulate studio lighting with “Strobe Mode,” which keeps the lights dim during stand-by, then ramps the lights up to full power only for the length of the exposure—similar to the experience using modeling lights in conjunction with a strobe. The exceptional color reproduction of the DT Photon series balances out its shortcomings in flexibility. While it can be taken on location, it’s not an especially compact light; and while it can be used to illuminate three-dimensional objects, it’s not suitable for more complex lighting scenarios such as those called for when imaging objects with challenging, specular surfaces like glass or bronze. In short, the DT Photon excels as a purpose-built light focused on reproduction of works on paper and other two-dimensional pieces.
The Broncolor LED F160 marries the qualities of a highly color accurate LED with the flexibility of traditional studio lighting. The F160 boasts a CRI of 97 and a CQS of 95, which is not quite as high as the DT Photon series, but exceeds the scores of many studio strobes. It also utilizes the same modifier/accessory mount as the rest of the Broncolor family, meaning it can be used with a softbox, reflector, grid, and more. This points to the Broncolor F160 as a strong choice for museum photographers looking for a continuous light source with solid spectral properties to tackle objects with challenging surfaces that require more elaborate lighting than the standard 45º configuration.
Those interested in power output will note that, measured from the same distance (1m from the light), the Broncolor F160 with a soft box is roughly 1.5 stops darker than the DT Photon 19” light with its standard diffusion panel. It has more than enough power output for small- and medium-sized objects, but is not ideally suited to large-scale objects or oversized materials. For such oversized materials, we would suggest a DT Photon XL instead, which puts out 2.5 stops more light.
In conclusion, when selecting continuous lighting for a CH Digitization program both color quality and flexibility must be considered. Color quality is a complex and involved topic, but CQS is the best single-number summary of color quality to look for. If you are mostly lighting works on paper and flat artwork we suggest the DT Photon series – it will provide the absolute highest possible color quality (98 CQS). If you are mostly lighting 3D objects in creative ways the Broncolor LED F160 provides greater flexibility for light shaping tools while still providing very good color quality (95 CQS).
Digital Transitions sells both of these products and is glad to loan a DT Photon LED or Broncolor LED F160 (or both) to anyone considering them for their studio so that they can do their own testing and evaluation. Feel free to reach out to us with any questions you have.