GHL Mitra Owners club

[kien]

Originally Posted by Reef Pilot

It is the surface water ripple that does it with my Radions. When I turn off the pumps, it disappears.

It is indeed the water surface agitation that does it with any point light source. It is called the caustic effect. A caustic or caustic network is the envelope of light rays reflected or refracted by a curved surface or object, or the projection of that envelope of rays on another surface. The caustic is a curve or surface to which each of the light rays is tangent, defining a boundary of an envelope of rays as a curve of concentrated light. In our case the curved surface is the water surface as it ripples and waves. The caustics can be the patches of light or their bright edges. These shapes often have cusp singularities.

Concentration of light, especially sunlight, can burn. The word caustic, in fact, comes from the Greek word for burnt, via the Latin causticus, burning. A common situation where caustics are visible is when light shines on a drinking glass. The glass casts a shadow, but also produces a curved region of bright light. In ideal circumstances (including perfectly parallel rays, as if from a point source at infinity), a nephroid-shaped patch of light can be produced. Rippling caustics are commonly formed when light shines through waves on a body of water.

Another familiar caustic is the rainbow. Scattering of light by raindrops causes different wavelengths of light to be refracted into arcs of differing radius, producing the bow.

T5s do not produce noticeable caustic/shimmering because the light is more enveloping as opposed to being focused like a point source. In essence there is no point source of light from a T5.

LEDs on the other hand typically have several point sources. Each point source producing a caustic. The further apart the individual LEDs are the more pronounced that particular channel's (colour) shimmer/caustic will be. The closer together the individual LEDs are the less pronounced it will be.

Radion LED array:


Mitras LED array:


Kessil 350W LED array:


Caustics on the sandbed from the different LED point sources:




Again, some people will notice it while others will not and at varying degrees of noticeability. If you don't see it or you don't notice it or you're simply not bothered by it then it doesn't really matter what other people see.

[Reef Pilot]

I haven't noticed it for a long time. But when you guys started talking about it here, had to go look at my tank to see it.

I kind of like it though. It only shows up on the sand bottom, and reminds me of snorkeling and seeing the wave shimmers on the sand.

[kien]

Originally Posted by Reef Pilot

I haven't noticed it for a long time.

Ya, I think that eventually you just get used to it. For a long time I ran just halides on my main tank and got so used to the shimmering from the halides that whenever I saw someone's T5 tank it just seemed odd to me.. Then I set up a second tank with strictly T5s over it and over a short period of time I just got used to it and was fine with the lack of shimmer on the T5 tank. Sometimes I think that our knee jerk reaction to something that's different from what we're used to it is to freak out.

[sphelps]

Come to think of it this is an owners clubs not a renters/borrowers club, sorry Kien but I don't make the rules.

[Aqua-Digital]

Just want to add an important point here

You wont see any disco ball effect with the Mitras. The reason for this is in the reflectors (not lenses) The reflectors converge the LED output to a uniform spread (convergence) eliminating any hot spot or higher intensity spot.

98% of the LED output is reflected back into the water matching that of a T5 reflector.

The Mitras was developed along with a leading University in Germany over two years, so there are a number of cutting edge technologies employed.

This spectrum analysis against ATi 54W T5 is quite impressive



The light blue thin line is the ATi

[subman]

I was up late last night wrapping presents (way later than normal lol) I noticed my Mitras were on all night even though the display was zeros across the board. I'm guessing it is just moonlighting.
Where is the setting to turn this off or at least make it much dimmer?

[Aqua-Digital]

In the software, you need to set a zero point time for example

11pm 0%
6am 0%
7am 10%

then between 11pm and 6am all will be off

[subman]

I'm sure I did that, I'll have to double check.
Michael what's the latest firmware?

[Aqua-Digital]

1.07 is the latest

make sure the channels are all at zero too

[subman]

got it I had all the channels at zero but had to set 2 new points on the light composer and now its black out from midnight to 4am

Now that I have used it a bit more the software is great. The first time I set things up I didn't use the light composer, I just set up each individual channel. The light composer is pretty slick