HOW TO LIGHT PHOTOGRAPHIC PRINTS
How to Light Photographic Prints
If you are a consumer, you may have just invested thousands of dollars on one or more prints to anchor your decor. If you are a photographer, you clearly will want to show off your own work at your business or in your home. This article provides information on the best way to do this.
We will take a look at the following important issues:
- What lighting source types reduce the possibility of damage from heat or ultraviolet light?
- What lighting position reduces glare and reflections the most?
- Can lighting be attractive?
- What if prints are moved often? Can the lighting be adjusted easily?
- How does color temperature of the lighting affect the display of the print?
- What are the advantages and disadvantages of different bulb types?
Previous articles have discussed selections in glazing (glass, acrylic or none) to reduce glare and to provide UV protection. Reduction in glare, in particular, can provide some sacrifice in color rendition, so this article discusses situations where the artist’s work is displayed behind a reflecting material.
Ideal Color Temperature
The color temperature to illuminate and show off art should not be confused with the color temperature that photographers use to create an artistic photograph. Outdoor light is on the cool side of the spectrum, usually from 5000K to 10000K. Photographers most often take and process their photographs in this range. Indoor photography, such as classical portraiture might be considerably warmer. Displaying photographic prints at outdoor light temperatures may make them appear very cool, however, so warmer color temperatures are often chosen. Most art galleries find that color temperatures warmer than 3000ËšK are too warm. In addition to bulbs coming in various color temperatures, some bulbs have adjustable color temperatures, either by a setting on the fixture itself, a button on a remote or wall switch or via a smartphone app.
Your light source?
Our choices of types of lighting are natural light (ambient or direct), incandescent bulbs (traditional light bulbs), fluorescent bulbs (those long ceiling bulbs), halogen bulbs (often used in track lights) and LED lighting (available in many forms). An ideal selection would not emit UV light which will fade colors over time, would not produce heat and would have an ideal color temperature.
Incandescent light bulbs
Incandescent bulbs are also available in a range of color temperatures. Soft White (roughly 2700K – 3000K), Cool White (3500K – 4100K), and Daylight (5000K – 6500K). Incandescent lights emit a small amount of UV light and they produce considerable heat.
Fluorescent bulbs
Fluorescent bulbs are found in many office and store ceiling fixtures and occasionally in kitchen ceiling fixtures. They emit the most UV light of any bulb but they produce little heat. Fluorescent bulbs are available in color ranges from 3500K to 6500K. If you are hanging valuable artwork in a situation where fluorescent bulbs must be used, there are UV filter sleeves available to slide over the bulbs and there are UV filter sheets available to fit 2’x4’ fixtures. Compact fluorescent bulbs (CFL - looks standard incandescent bulb acting like a coiled snake) are available for lamps.
Halogen bulbs
Halogen bulbs are often used in recessed ceiling fixtures, track lights and flood lights. While they are most available in at 3000K color temperature, they may also be found at a cooler 4000K color temperature. Halogen bulbs produce small amounts of UV light, but operate at a high temperature range, giving off considerable heat. Their lifespan is shorter than most other bulbs which makes them inconvenient for ceiling fixtures. Due to their higher energy consumption, manufacture of halogen bulbs has been discontinued. These should be adequate reasons for you to replace any halogen bulbs remaining in existing fixtures.
LED bulbs
LED bulbs have become our most available lighting source and there is good reason. They take less energy. They produce operate at a very low temperature. The are available in a wide variety of color temperatures, from 2200K to 5000K. They produce a minimal amount of UV radiation. Their lifespan is much longer than most bulbs. All of this tends to justify their higher cost.
Do you want dimmable lighting?
All the bulb types are dimmable except for some compact fluorescent bulbs. However, fluorescent bulbs may require a special ballast in the fixture and LED bulbs may require a special dimmer switch that is more sensitive to their lower wattage. Be sure to check compatibility before purchasing and installing new LED fixtures with dimmers.
Wattage vs Lumens
Wattage refers to the energy consumed, while lumens refers to the effective light emitted. The best way to measure the intensity of light available from a bulb is by lumens. For those of us used to incandescent light bulbs, a 75 watt bulb produces the approximate equivalent lumens as a 10 watt LED bulb. In other words, an LED bulb is about seven times more efficient than an incandescent bulb. Both a 75 watt incandescent bulb and a 10 watt LED bulb produce about 1000 lumens of light.
Color Rendering
So let’s assume we have decided on LED lighting. LED bulbs create white light by combining blue light with a yellow phosphor. This makes LED bulbs naturally better at lighting blues than reds. The ability to accurately render all tones of the spectrum is measured by the Color Rendering Index (Ra or CRI). To avoid washed out warmer tones in portraits and landscapes, look for a CRI of 90 or more. Another measure of the ability to render reds is the R9 value. An R9 value over 80 is recommended.
Ideal light positioning
Pictures can be hung at a variety of heights. They may be high on a massive fireplace or even at the level of your dog’s bowl! But most pictures are placed at a pleasant viewing height where the horizontal center of the picture is 57” to 60” above the floor.
Angle of light
Assuming we have our picture positioned at an ideal height we can look at how to minimize reflections from lighting on that picture. It is also important to have lighting positioned so observers do not have their shadows from the light cast on the artwork. An ideal incident angle of 30 degrees is referred to as the museum angle. You may increase this angle a bit if your frame is likely to cast a shadow on the print or you may increase the angle a bit if you want to emphasize texture on adjacent art pieces.
The best position for lighting depends on the height of the artwork and the height of the ceiling or available rafters. There is a great deal of flexibility with track lights, but the power source might be exposed, which might not be acceptable for some home locations. Ceiling joists can affect the position and number of recessed can lights. For purposes of providing the best display of art, however, the most important thing is to get the angle of light correct. The 30 degree angle shown minimizes the reflection of of the face of the artwork so that the viewer can enjoy the piece to the maximum.
When reflections of light coming through windows on opposite walls is a problem, this may be addressed with changing the glazing on the artwork. Options are in the article, Cover That Print.
Extremely high ceilings (say 12' plus) can be a problem due to the diminished output of the light at the increased distance and potential obstructions blocking a portion of the light. A suitable alternative might be extension drop rods from a track system attached to the ceiling. This will result in lower lighting costs and more control on the placement of the light. In this image, you can see that the gallery with 14' ceilings found a creative way to make its lighting system artsy. These rods are readily available from lighting supply stores.
Light Spread
You are likely familiar with the terms “spot light” and “flood light”. Spot lights give a narrow beam of light and flood lights give a broader beam of light. For LED bulbs the angle of the spread of light is determined by the lens, i.e. the front cover of on the light bulb. LED bulbs come in spread angles from 10° (very narrow spot) to 60° (wide flood). Some fixtures, such as the Elco fixture shown below, also come with replaceable lenses, allowing some modification of the spread angle. The angle of spread for your particular situation is determined by the size of the artwork, the distance light source is from the artwork and whether you are using multiple lights on one artwork. In most situations it is best to confine the lighting to the artwork and not spread it any further onto the walls than necessary. There are some quite expensive fixtures that allow you to adjust the angle of light spread. These would be used primarily in museums and high end art establishments. If interested, see Banno Lighting.
Whether you choose one or more bulbs to light a particular artwork will depend on a variety of factors. If you place multiple artworks on a wall and the lighting is all controlled by one switch, then you will want to balance the amount of light to each piece according to the distance from the art and effective lumens of each bulb. If you have dimmers on multiple switches, you may be able to balance the light using those dimmers. A wider beam for that larger piece of art will result in less light so you will either need to light it with multiple wider beam lights focused on the same are or multiple narrow beam lights focused on different areas. Panoramic (2:1 ratios and greater) will require multiple light sources to keep from over washing too much wall area.
You will not have to worry about how that spread angle affects the lumens that the LED bulb emits.
To determine the best angle of spread for your bulbs, use this table.
The table contains spread angles that include narrow spot lights and wider flood lights. Note that the light coverage will be slightly narrower and stronger towards the top of your picture and wider and weaker towards the bottom of your picture.
In general, lighting at a greater distance or at a wider angle will provide more even light, require stronger wattage and cost more in electric bills and replacements. Strike the balance you are comfortable with in making your selections.
One higher end bulb manufacturer (Soraa) offers a snap system with replaceable covers over the bulbs that modify the angle of light spread
Track lights or recessed lights?
The most common options to light wall art are track lights and recessed lights. The latter can be further divided into can light versions and flat mount versions. Let’s compare the these options.
If you have existing recessed lights
Recessed or can lights are in many homes. Existing lights are usually down lights (point straight down) with bulbs flood bulbs with angles of light up to 90Ëš. Special recessed down lights are available for sloped ceilings. A major advantage of down lights is that it is easy to mix down lights (say to light a reading area) with angled lights for artwork on the walls.
Most recessed lighting is in 4 inch, 5 inch or 6 inch sizes. You may purchase adjustable lights with trim to retrofit your existing fixtures. Check to see if your existing fixture has screw-in bulbs. If so, you will need to purchase a 120V fixture. If your existing fixture is low voltage it will have a two pin plug. In this case, purchase low voltage replacements.
For Remodeling Applications
Can lights can be placed in many remodeling applications. Just be sure you pick up the correct model for this application. When there is inadequate vertical space in the ceiling it may be easier to install a canless recessed options are available. Many of these fixtures do not require a fixed junction box. The canless variety will have a contained bulb rated for tens of thousands of hours. Once depleted, the unit will need to be replaced. An example with 360Ëš rotation and angle adjustment is made by Satco. This is a "smart" light with color temperature adjustment possible from a phone app.
The Best Use for Track Lights
Track lights are ideal for galleries, especially when artworks are changed often resulting in different artwork locations and sizes. Track lights can be easily moved to a different position on the track and are easily rotated or angled for best appearance on the art. It may also be possible to easily add light fixtures to the track. Most track light alternatives accept separate bulbs, allowing you the maximum flexibility to choose the best bulbs for your purpose. Museums, galleries and art investors looking for the ultimate in track fixtures should consider Bannon Lighting. Some fixtures have adjustable light spread (focus) and minimize glare. For all new ceiling fixtures designed to light artwork, be sure that they will tilt to at least 60 degrees and rotate 360 degrees.
When directed downward, this Elco "can" fitting will fit flush with the ceiilng. It can be angled up to 95° and can be rotated 360°. Check the specifications on any fixtures before you purchase.
I have always thought of bulbs for ceiling fixtures in three sizes: little ones that go in most track lights, middle sized ones for small can fixtures and big ones for those large can fixtures. I knew that there were flood lights that spread out the light a lot and spot lights that confine the light beam to a smaller area. Understanding bulbs in more detail will help you with your selections.
In addition to the sizes, bulbs have a reflector and a connector. The small bulbs are labeled “MR” which means multifaceted reflector. The MR11 bulb has two pins that are 4 millimeters apart. The much more common MR16 bulb has two pins that are 5.3 millimeters apart. Bulbs with pins are used in low voltage (12V) fixtures. If you are using a low voltage fixture you will need to recognize what size fits your fixture before you go shopping.
Line voltage (120V or 240V) are also have multifaceted reflectors but are termed “GU”. These bulbs have cylindrical buttons as connectors that allow them to be twisted into their receptacles. A GU10 bulb has the connectors 10 millimeters apart the bulb is the same size as MR16 bulbs. A GU20 is a medium sized bulb with the connectors 20 millimeters apart. A GU24 bulb is a bit larger and a GU30 bulb is a large sized. There are fully adjustable fixtures available for all of these bulbs.
If you have existing can lights you will be interested in “PAR” bulbs. PAR means there is a parabolic aluminum reflector inside the bulb. These bulbs have screw bases like standard sized light bulbs. PAR20 bulbs are medium sized and PAR30 and PAR36 bulbs are a larger size.
LED bulbs have their lumens listed on packaging. If you don’t find it, use this table for the lumens based upon wattage.
You may find the approximate lumens of wattages not listed by estimating. There may be some minor differences in bulbs of the same wattage due to efficiency differences.
Light and Distance
A physical property of light is that it diminishes by the inverse of the square of the proportionate increase in distance. If you double the distance, you decrease the light by a factor of four. For example, an artwork that is ten feet from the light source will only receive one-fourth the light that it would if it were five feet from the same light source.
1/(10/5)2
If math scares you and you want to know the effect of moving your light closer or further, use the following table that assumes 100 percent light at four feet.
You will notice the tremendous effect from moving your light source further away. You will use this information to help select the correct bulbs to light individual pieces of art. It is also important to understand that lumens is a measure of light output from the bulb. It does not measure the light that falls on a surface. A more focused beam of light means the light will be concentrated and thus more intense on the artwork surface.
There are other factors that may affect your lighting selection including reflectivity of the artwork and that of adjacent walls, ambient light and room lighting and any desire to emphasize certain artworks over others.
You will use all the information provided to select your lighting fixtures, individual light location and the specific bulbs types.
Here websites where you may buy fixtures and bulbs:
Build.com
1000 Bulbs
Bulbs.com
Review
- Select the type of fixtures that work for your space.
- If you are able, locate individual lights at a 30 degree angle to the center of your artwork.
- Select bulbs with a spread angle based upon the distance from the artwork and the size of the artwork. Balance amount of light (lumens) from your individual bulbs based upon the ambient room light and and the desired light on each artwork.
There is an ongoing argument about whether light or composition is more important. Be sure the light captured by the artist is properly exposed with your gallery lighting so we can keep this argument going.