[KevinJ]

I have read with interest some of the fascinating posts on YD and thedecostop from Barry Miller (Salvo Diving) and Rob Dobson. For the most part I’ve tried to stay clear and hope that most divers are smart enough to see Barry’s posturing for what it is; A means to protect his business.

Of particular interest are the posts and photographs cross-posted on both forums to disprove the “false and misleading claims made by SOLUS as to the output of their product” as Barry puts it.

As a number of people on YD have pointed out, the test is hardly being conducted by the most impartial person. Some have also pointed out flaws in this “testing”.

The obvious flaws are:

• The test is being run in air and not in water. The SOLUS SU-1250 will lose 1% of it’s light output for every degree C over the design temperature. If left running for more than a minute the light output will have dropped by up to 25% from it’s design rating.
  Conversely the HID lamp will produce slightly more light in air when it runs hotter.
• The test is being run in air and not in water. The beam angle of the light will narrow by almost 1/3rd when placed in water, due to the same refraction that causes things to look larger and closer when you’re underwater. As the beam angle becomes narrower and the illuminated area smaller, the light intensity increases. The wet reflector design used by Barry Miller in the Salvo lights maintains the same beam angle in/out of water.
• You cannot characterise a beam by taking one measurement with a light meter.
  The correct method is to take multiple measurements at various positions within the beam and average these to get a number, which will represent the amount of light present.
• Barry repeatedly misrepresents the measurements as Lumens. The measurement you get from a light meter is Lux, not Lumens. The definitions are referenced at the bottom of this post, for those who want to know the difference.

Of particular interest was the photograph showing the 10 Watt focusable Light Vs SOLUS SU-1250. Assuming that this photo was taken with the SU-1250 on full power, this image should be a good starting point.



We took this image and ran an analysis on it using E-Vision Capture, a piece of software designed and used by professionals in the machine vision and lighting industry for image analysis. This is the original image – there has been no post-processing of any kind.

Barry Miller claims that the SOLUS produces less than a quarter of the light of a 10 Watt HID lamp. A measly 180 Lumens as opposed to the mighty 800 Lumens from the HID. What Barry is actually measuring is Lux. There is a relationship between Lux and Lumens but they’re not interchangeable.

Below is the 3D surface profile of the image showing the relative light output from the (left) 10Watt HID and (right) SU-1250. The volume under the mounds represents the total luminous output of each of the beams.
The Z axis or height is generated from the illuminance of the image. (The contrast of white to black)



From this perspective it’s obvious that the 10 Watt HID has a higher intensity at the centre of the beam, however it’s not by much (between 10% and 15%). For some strange reason this doesn’t seem to match up with the numbers quoted by Barry. You’ll also note that the mound on the right (SU-1250) while having a slightly lower intensity, covers a much greater area. (this is important)

The next image shows a plot of the illuminance over the original image.



The area under the red plot line represents the amount of light in the image passing from left to right (Sum of the light in the y axis).
As you can see, the area under the plot line for the HID is approximately 1/3rd of the area under the plot line for the SU-1250.
It is clear from the plot that the SU-1250 produces at least 3 times the amount of light of the Salvo 10 Watt HID.

This would support our claims that the SU-1250 produces the same amount of light as a 35 Watt HID lamp. Given that the SU-1250 being tested was being run in air it would likely have been running 20-25% under it’s rated light output anyway. (If it was even set on full power)

I have no doubt that Barry will come back with claims that it’s all smoke and snake oil but it isn’t. It’s just a little bit of science and mathematics.

We encourage anyone who is suitably qualified and has access to tools such as MatLab or any of the other excellent image analysis packages to validate this with the images posted by Barry.

As far as Barry Millers statement regarding “false and misleading claims” made by SOLUS, how does he justify his claims that the Salvo 10 Watt HID lamp tested produces 800 Lumens and the SOLUS SU-1250 produces 180 Lumens?

I had hoped that this wouldn’t come to a debate on a public forum but Barry Miller’s (and Rob Dobson’s) repeated attacks didn’t leave too many options.
I would hope that this will put an end to the argument and has sufficiently demonstrated that the SOLUS SU-1250 produces at least 3 times the light output of the 10Watt HID lamp used by Salvo. And that this has been demonstrated using the images supplied by Salvo.

I generally try not to debate physics, as physics is what it is. It doesn’t change no matter how much you argue over it.
In particular I try not to debate with a fool as sometimes it’s hard for onlookers to tell the difference

For those who want to make up their minds for themselves, visit our stand at the DIVE2007 show in October, We’ll be on stand 1154 in Hall 9. For those further away, one of us will be on the Oxycheq stand at DEMA to answer your questions.
We’ll have all our products on display and our demonstration box there to show how a 10Watt HID, 35 Watt Halogen and a 250 Lumen LED Array (1st generation) all produce similar light levels with the same beam characteristics. If anyone isn’t clear on the refraction of the light beam in water we can even bring a fish tank along to demonstrate this effect.

Kevin Jury,
Managing Director
Solus Submersible Products


LUMEN:
A unit of light flow or luminous flux. The lumen rating of a lamp is a measure of the total light output of the lamp. The most common measurement of light output
(or luminous flux) is the lumen

LUX: The metric unit of measure for illuminance of a surface. One lux is equal to one lumen per square meter.