By on 2009-06-24

Authored by John Williamson:


The Westcott Spiderlite TD5 is the most powerful, flexible, and comprehensive lighting system available today. The Spiderlite TD5 delivers constant light at over 900 watts of power output, provides daylight balanced color temperature at 5500 degrees Kelvin and is portable enough for any location work. The Spiderlite TD5 has built-in softbox receptacles so there is no need to carry extra equipment saving both space and weight. There is also a built-in umbrella mount in the tilter bracket for those jobs that require using a Westcott umbrella.


When you hear that, “the Westcott Spiderlite TD5 provides constant light at over 900 watts of total output,” that all sounds good but what does it mean? You may say to yourself, “my strobes are 300 watt-seconds so the Westcott Spiderlite TD5 MUST be more powerful.” You might also ask, “Why does my 300 watt-second strobe put out more light than a less expensive 600 watt-second strobe?” These are great questions that a lot of manufactures don’t want asked.

So let’s break it down.


Watt-seconds commonly refers to the power rating of a photographic strobe unit. The definition of a watt-second is a unit of electrical energy that is equal to the “work done” when a current of 1 ampere passes through a resistance of 1 ohm for 1 second. What? Basically, it is a measurement of ENERGY, not LIGHT. It’s important to understand that energy does not equal light. If one brand of strobe uses top-of-the-line capacitors in their strobe unit (like PhotoBasics does) and you compare it to a brand that doesn’t you will find that, although both strobes are rated for the same watt-seconds, they produce a different amount of light output. So now you have a unit of measurement (watt-seconds) that isn’t measuring the amount of light that is produced. Furthermore, it isn’t governed by any standards. This leaves you, the consumer, out of luck.

This doesn’t even begin to cover the constant light that is provided by Westcott Spiderlite TD5s.

Enter Westcott.

In our ongoing quest for consumer education, Westcott has developed a unit of measurement that will provide you with the amount of LIGHT that is produced. Keeping the consumer and professional photographer in mind, Westcott uses the same language we all speak; the language of exposure. AMR or (actual meter reading) is a method of recording the actual amount of light that any given light-producing unit will output, be it constant or strobe. By recording data in a constant environment under strictly consistent and repeatable conditions we are able to give actual meter readings (or AMR’s) that represent the light output of any light at full power.

The parameters we used to measure the light output were:

* center of the light source 5 feet from the ground

* 24″ x 32″ softbox with the front diffusion panel only

* Sekonic L-758 light meter positioned exactly 5 feet from the front of the softbox – exactly 5 feet off of the ground from the center of the hemispherical diffuser

* entirely dark room.

The light meter was set to ISO 100 @ 1/125th of a second. The metered aperture is now your AMR reading. It’s that easy. Because every light is tested within the same parameters, we now have a standard with which to compare light output. Plus, the output data is now provided in a way that is actually usable by photographers. Genius!

Alright, so it’s starting to make sense now and coming together. Let’s look at some real world examples that will demonstrate how this information can be used.

I shoot with the Westcott Spiderlite TD5. The AMR on the Spiderlite TD5 with the new 50 watt fluorescents measures 1.4. I want to shoot a corporate head shot but the VP only has 2 or 3 minutes between meetings. We have to do this quickly. By simply adjusting the known exposure of my Spiderlite TD5, thanks to my AMR, I know that I can shoot at f2.8 @ 1/60th @ ISO 200. That exposure is equivalent to the AMR of the Spiderlite TD5. My camera is set and the VP isn’t even in the room yet. I pop open a Westcott Collapsible background, position my Spiderlite TD5 with a 24″x32″ softbox and I have a portable studio setup in less than a minute.

VP walks in. I flip the switch on my Spiderlite TD5. Shut off the over head lighting (please, please, please remember to shut off the ugly, horrible, disgusting overhead lighting) position the VP (who will not get hot under the cool lamps of the Spiderlite TD5) and ‘click.’ You’re done. The VP walks out, still on time for his next meeting and VERY impressed with cool, clean, efficiency of the new photographer. Man I love my job!

Since the Westcott Spiderlite TD5 utilizes constant light, it allows me to fluidly adjust the lighting pattern on my subject. The beauty of the Spiderlite TD5 is that what you see is what you get! The Spiderlite TD5 is small and lightweight so it deploys rapidly in any situation, in any environment, making it easy to go from studio to office building to church basement. How great is that?




There are also other members of the Westcott Spiderlite family. We have the Spiderlite, a 500 or 1000 watt tungsten light with a mogul base; then we have the Spiderlite TD3 which utilizes three Edison base sockets for tungsten, strobe, or fluorescent lamps; and finally, we have our flagship Spiderlite, the most versatile Spiderlite in the fleet, our Spiderlite TD5!

The Spiderlite TD5 uses five Edison base sockets controlled by three switches. When used with our new 50 watt fluorescent bulbs, we have over 900 watts of power with none of the heat, making the Spiderlite TD5 the choice of professional photographers around the world.

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1 Comment

  • I have been doing a lot of research in preparation of purchasing studio lighting and I see one comment over and over. I keep seeing people say that the TD5 is underpowered, that you cannot shoot a 1 light setup unless the TD5 is right on top of the subject.

    I’m not sure what these folks mean by that as I have always shot my speedlites close to the subject as well, so I am not sure what this means. Can a hot strobe light be 5 to 6 feet away from the subject?

    In your setup shot it would appear that the key light is about 3 feet from the subject, is that about right?