How to Pick a Reading Light
I fell in love with reading at a very young age. I try to read as much as possible, but, with my life getting busier everyday, I find less and less time to read a book during the day. Thus, night time leisure reading became a habit for me. I needed a good reading light for night time reading. My first few reading light purchases left me feeling disappointed. That is when I started to learn about lights. I learned a lot during my search for the perfect reading light. With this post, I hope to share what I learned about reading lights. These are the top five things (in no particular order) you need to consider when buying a reading light.
1. Form Factor
Form factor refers to the size, shape and other physical characteristics of the reading light. This is the first thing (and sometimes the only thing) most people consider when they shop for a reading light. Reading lights come in a wide variety of form factors:
- Desk lamps
- Bedside lamps
- Clip-on reading lights
- Neck lights
- Headlights
Desk lamps are ideal for those who do most reading on a table top. A desk lamp with a flexible arm allows you to position the light where you need it. Various types of bedside lamps are available for night time reading; Some can be placed on a small table near the bed; Others can be clipped on to the side or the head board of the bed. If you like a more portable option, you can opt for a clip-on reading light, a neck light or a headlight. A clip-on reading light is clipped on to a book or your dress. A neck light can be worn around the neck. Headlights are worn on the head with a special band. General purpose headlights made for repairs and other tasks are not suitable for reading. They tend to have harsh spot lights and often too heavy to wear for an extended period of time.
2. Illuminance (Lux)
Lumens measure the total quantity of visible light emitted by a light source per unit time. It is a measure of light output or brightness. Illuminance is a measure of how much the incident light illuminates (light up) the surface. The SI unit of illuminance is lux. One lux (1 lx) is equal to one lumen per square meter. Twenty five to fifty lux is recommended for eye-strain free reading. However, the amount of light required for comfortable reading may vary from person to person. An older person with a slightly degraded vision might need a bit more light compared to a younger person. Therefore, it is a good idea to opt for a reading light with adjustable levels of brightness. This allows you to pick the right amount of light for your reading.
3. Correlated Color Temperature (CCT)
In simple terms, correlated color temperature or color temperature tells you how yellow or blue the emitted light from the source is. CCT relates the color of an emitted light to the color that results when an ideal black-body radiator is heated to a certain temperature. CCT is measured in Kelvin (K). CCT values of most commercially available light sources range from 2500K to 6500K.
Low color temperatures (warmer colors) tend to be yellowish while high color temperatures (cooler colors) tend to be bluish. While there is no agreement as to what exact color temperature range constitutes warm white or cool white, we can broadly divide CCTs into three categories as,
- Warm White (2500K-3000K)
- Neutral White (4000K) and
- Cool White (5000K-6500K)
What color light source you choose depends largely on your reading habit. A warm white light is best suited for night time reading as it has the least effect on melatonin levels. Melatonin is the hormone that helps you fall asleep. A cool white light improves overall attention and it may be the best choice if you want to stay awake for studying. A neutral white light is ideal for eye comfort and precision work. A neutral white light might be a good choice for colorful books as it reproduces all colors equally well.
4. Color Rendering Index (CRI)
Color rendering index (CRI) measures the ability of a light source to reveal true colors of objects in comparison to an ideal light. CRI is a number between 0 and 100. At a CRI of zero all colors look the same. True colors of objects are revealed at a CRI of 100. A light source with a CRI value greater than 90 is considered excellent.
5. Lens Optics
Most reading lights available today are equipped with LED based emitters. With the primary LED optic (this is the plastic cover around the LED light) you get the highest light output at the center. The light intensity fades off towards the corners. Most LED based reading lights are equipped with secondary optics to distribute the light evenly. The cheaper lights equipped with reflectors lose most light coming from the middle of the emitter. More expensive total internal reflection (TIR) based optics can control light distribution much better. A good reading lamp with a soft diffused light can illuminate a surface evenly. When you shop, look for soft diffused reading lights with TIR optics.
