A Lesson on Lighting – Updated

Earlier in this series, I did a few posts on the benefits of using natural lighting for your photo shoots (check the archives if you haven’t seen these yet).  But what about shooting with artificial lighting, say in a light tent or a light box?  Or how about just adding some supplemental lighting to your tabletop or floor setup?  Choosing the right lights can make all the difference in any of these situations.  So today I’m going to give you some lighting basics, help you to be a smarter shopper and even give you my recommendation.  To keep things as simple (and as brief) as possible, I’m only going to be covering “Compact Fluorescent Lamps” (CFLs) today.  These bulbs have become pretty popular, and they’re nice for photography because they’re cool enough that they won’t set fire to your light box like a halogen or incandescent bulb can!

What’s a Watt?

Don’t worry about it!  Seriously, a watt is nothing more than a standard unit of power, just like a second is a standard unit of time.  In terms of choosing lights for your photography, it’s pretty much meaningless unless you’re trying to save a few pennies on electricity.  A watt is a measure of how much electricity a bulb consumes, and it has nothing to do with how much light is produced or what that light looks like.  The only thing you need to know is that generally, for a particular type of light, “more watts = more lumens.”

Lumens?  Huh?

Want to compare different lights?  The first step is finding the “lumens” rating on the packaging.  You don’t need to know this, but a lumen is a measure of “luminous flux.”  That’s a measure not of how much light is emitted by a bulb, but rather how much of that light makes it to a specific target.  Need more details?  Just ask – I’ll be happy to oblige.

But all you really need to know regarding lumens is that “more lumens = brighter light.”

What Does “Color Temperature” Mean?

Simple…

Lower temperatures = more yellow = warmer look

Higher temperatures = more blue = colder look

Here’s a pretty picture saying the same thing:

So what’s a “Daylight Bulb”?

There’s really no such thing!  Think about it.  Look at the color temperature graph above.  Look at the difference in color temperatures at different times of day.  Now confound things even more with different times of year and different weather conditions.  Think about it some more.  Picture yourself outside at the beach at sunrise or sunset versus mid-day.  Or just go outside right now (if it’s during the day) and look at the sky in several different directions.  Does it look the same?  No way!

The best a bulb can do is to provide light at a specific “correlated color temperature” (CCT, for short).   The CCT is simply an approximation of the color temperature as our eyes perceive it.  So a 5500K bulb can only be a “daylight bulb” at a particular time of day, during a particular time of year, under a particular set of weather conditions.

But it’s a start!

Full Spectrum Bulbs Are Good, Right?

Absolutely!  If you can figure out what that really means.  “Full spectrum” means all the colors of the rainbow, plus a little infrared and ultraviolet.  Sunlight is full spectrum, as this spectragraph shows:

Are there any lights that actually match this spectrum?  NO!  That’s a pretty straight-forward answer, right?  Okay, let me expound on that a little bit.  Umm … NO!  Sorry, that’s all I got.  Some lights do cover a wide range of wavelengths (colors), but unless you can find a spectragraph for those lights, you really have no idea what you’re getting.  Seeing “Full Spectrum” written on the label is not enough!

What the Heck does “CRI” Stand For?

CRI is short for “Color Rendering Index.”  It can be important when you’re shopping for light bulbs for your photography.  It’s an old and somewhat obsolete standard, geared more toward video production, but it’s the best information we have available right now that represents how closely a light can reproduce colors in comparison to an “ideal” (whatever that means) light source.

Don’t pay too much attention to CRI values, other than these two considerations:

  • All else being equal, a higher CRI is better than a lower one, and anything above 90 is good for our purposes.
  • The difference between a few CRI points is meaningless, so don’t get hung up on comparing between values like 89 and 91.

Are “OttLite” Bulbs Any Good?

Well, yes and no.  There’s really nothing wrong with them.  But they’re not that special either.  There are plenty of CFLs on the market with equal or better specs.  Although the OttLite website isn’t very informative, and their packaging and labels are pretty useless, I did manage to get my hands on some data for the three CFLs that they offer.  To save you all the trouble of searching for the information, here are the specs for their “brightest” bulb, the 25EDP2R.

  • Luminous Flux – 1300 lumens
  • CRI – “Above 90”
  • CCT – “Between 5000 and 6000”

The specs for CRI and CCT are a bit vague, so I asked the OttLite folks for more detailed information.  Nada.  I also asked for a spectragraph on these bulbs (to see how they compare to natural light), but they told me that the information was proprietary. Oh well.

Okay, So What Do You Recommend?

Well, a lot depends upon your specific application.  But you can’t go wrong by following these three simple guidelines:

  1. Get unstuck from the “brand name” mentality.  Buy based on what the product does, not what it’s called.  Generic acetylsalicylic acid is a better bargain than Bayer aspirin, right?
  2. Learn what’s important about what you’re buying (luminous flux, CRI and CCT) and compare that information between bulbs.
  3. If you can’t find this information on the packaging or the website, don’t buy the light.  Period.

Luckily, there are a lot of options, and now that you know what’s important you shouldn’t have any trouble finding appropriate bulbs for your photography needs.  If you want me to point you in the right direction, I prefer bulbs manufactured by Alzo digital.  The company offers quite a variety of products and their prices are very reasonable.  Alzo bulbs can be purchased directly from their website or from any number of online retailers like Amazon.com.  Or, if you decide against Alzo altogether, there are plenty of other options.  You just need to do a little research, compare some specs, and make sure you’re getting the most for your money.

Until next time … Happy Shooting (and Shopping)!

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