Here’s a quick comparison of the Lightpanels 1×1 Superspot and the Shantou Nanguang CN-600HS 1×1 panel. My goal with this test was to see how a $350 Chinese knock-off compares to the nearly $2000 U.S. offering and to compare both panels to a tungsten Lowel 250watt Pro-light serving as a reference. (I prefer lighting glamorous talent with tungsten rather than daylight sources because the warmer source is more forgiving of blemishes and imperfections in skin.)

Now, I know comparing a spot fixture to a flood seems like apples and oranges but my main goal, with the fixtures I had at hand, was to test each of them for useable color and light output.

Note that, for this test, I didn’t delve into the intricacies of an LED source’s discontinuous spectral output or the many other variables that affect LED instruments.  If you’re interested in the challenges of LED lighting and how LED instruments render various colors, read the AMPAS Solid State Lighting Project.

Summary:

I measured color balance, brightness, and beam spread for each instrument.

color: At daylight color balance, both 1×1 panels exhibit a green spike – the CN600HS considerable more so. Both panels have a huge spike when converted to tungsten balance with a full CTO gel. Neither of these panels should be converted to tungsten. Nor should these panels be used to model talent under critical conditions without serious time spent on balancing them. I believe they may serve well as edge-lights and set rakes but don’t use them as a they key-light on talent.

luminance: Both panels pack a punch (for an LED source) and compare favorably with the 250watt Lowel Pro-light on full flood. The Lightpanels comes in at 240fc @ 5ft on center. The Shantou delivers 120fc @ 5ft. Compare that to the Lowel Pro-light which delivers 100fc @ 5ft in flood and 510fc @ 5ft in spot.

beam: The Lightpanels offering may easily be called a spot with its 10degree beam. The CN600HS plays more like a flood with its 30degree beam. (I measured the beam angle as 50% of the foot-candle reading at center.)

Here’s a zip file of the test charts.

Testing Method:

Each 1×1 panel illuminated a Gretag Macbeth chip chart at full power.  The chart was metered then shot with a RED One MX and Nikon 85m Ai/s lens. Simple color correction was performed with REDCine X Pro and a frame rendered for each setup.  I used the white color chip to grab a white-balance.  No deeper attempt was made at correcting the image.

Since my venerable Minolta Color Meter II is useless with LED lighting (it doesn’t understand discreet RGB spectra) I turned to my RED One MX at ISO800 as a color measurement tool. My Sekonic L-758 Cine meter served for measuring illumination. Rather than color correcting in-camera, REDCIne X Pro was used to white-balance the Gretag Macbeth chip chart. (I’ve found the RED One MX to exhibit a mild green cast and generally dial in a -6 tint when shooting and grading. That tint level served as my base reference for these tests.)

The biggest challenge in the manufacture of LED light sources is the incredibly variable output of LED’s themselves. LED’s come out of the manufacturing process with all manner of color and luminance variation and are then sorted (called “binning” in industry parlance) into groups of roughly equivalent color and luminance values. Lighting instrument manufacturers then choose the price-point they want to buy into and what additional power/current management and color/luminance controls they wish to include in their light source. This is the greatest source of price variation between vendors.

For a detailed review of the LED manufacturing techniques and their impact on set lighting, read Guy Holt’s excellent on-line paper: High Output AC LED’s

Note that my test results are for specific instruments with a specific camera.  LED lighting can vary widely from camera to camera.  Testing is the key success on the set.

Tungsten Reference:

A Lowel Pro-light with 250watt globe served as my tungsten reference point. It measured 3300K with very slight magenta cast. (I’m accepting -6 tint as my properly balanced standard.)

Litepanels 1×1 Superspot:

The Litepanels offering comes with the panel and power supply. Battery mounts, filters, etc. are extra. The power supply is a DC-to-DC switching type and mounts in a clip on the back of the panel leaving the A/C cord hanging from the instrument.  The head, itself, utilizes a constant current regulator to deliver rock-solid voltage and current to the LED banks. This model should, at the very least, be sold with the -green correction filter necessary to properly balance it. I’ve noticed more recent models have a slight pink cast in the plastic that protects the LED’s. Perhaps Litepanels has addressed this issue since the release of my instrument.

Here is the Superspot at daylight with no gels. It delivers a 5300K balance with no discernible tint. (Remember, -6 tint is my reference.)

But, oh my! Look at the Superspot with a full CTO added. Correcting requires a -18 tint to get the green spike.
Obviously, CTO does not handle the discreet red/green/blue output of LED luminaries properly.

Here’s what that looks like uncorrected. (Remember, -6 tint is our RED One MX reference point.) Clearly, more correction is required to make this a suitable luminare.

After testing with various amounts of -green gel, a 3/4 -green correction appears to bring the Lightpanels Superspot back into line. Unfortunately, we’ve also lost 2 stops of luminance in the process.

Shantou Nanguang CN-600HS:

This 1×1 panel is sold in the U.S. under several different OEM brands including ePhoto, G&L, and H.K. Wintech. It is obviously meant to compete one-on-one with the Lightpanels 1×1 flood instrument.  The panel comes with integrated barn doors, a hard filter pack (CTO, diff, -green), power supply, v-lock battery plate on back, and wired remote dimmer. These accessories would cost several hundred more dollars for the Lightpanels version. The power supply is built with a much lower gauge D/C cable and has no means of being mounted to the back of the panel, requiring a set electrician to sort out a strain-relief. The wired remote helps when the instrument is positioned above your head but could use a couple more feet on the cable to suit most situations.

The hard color gels are ostensibly CTO and -GREEN but have no markings to identify them. I measured them at full CTO and 1/4 -green respectively. I found the baby-pin receiver to be a bit frail and would replace that with a TVMP adapter as soon as possible.

Barn doors seem like a good idea with a flood fixture but have two main problems; a fringing at the edges of the projected pattern, and; interference from the instrument yoke in most positions.  (The yoke has a slight cant forward to reduce this issue.)

Of note, the power switch is “upside-down” with the “on” at the bottom and the dimmer knob rotates “backwards” according to Western tradition.  Rotate counter-clockwise to brighten, clockwise to dim.

At daylight, the CN-600HS exhibits a significant green spike (-10 tint) before adding any color correection.

The addition of the supplied 1/4 -green filter improves matters but still leaves a small green cast (-5 tint) that requires correcting in post. While I didn’t test it, I presume a 1/2 -green filter would get this instrument balanced correctly for daylight.

But, oh damn! Adding a CTO filter, like the Superspot, simply launched this instrument straight into green-spike hell.

An attempt to wrangle that green spike down required a full -green gel with the resulting 2-stop loss from all that filter correction clipped to the instrument. A minor -2 tint was required in post after all that gel correction.

Conclusions:

It is obvious Lightpanels has spent a lot of R&D hours designing their Superspot. Shantou Nanguang has obviously chosen to purchase LED”s from a lesser bin with the appropriate end result.

Neither instrument is suitable for correction to tungsten with currently available CTO gels. Perhaps, gel manufacturers will issue a version of CTO that addresses the unique colorimetry of LED instruments (although, judging by this simple test, that appears to be a vastly moving target.) It may become the responsibility of the gaffer to ascertain and rate each LED instrument on set much like he/she does for HMI’s. Until then, one must purchase separate instruments for daylight and tungsten situations or deal with the 2-stop loss from adding all those color correction gels.

So, are these instruments ready for a professional set? At daylight, they’re tolerable with a bit of correction. At tungsten, you sacrifice huge amounts of light output to get them to deliver a usable light.

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