As leds go, the lumens per watt specifications are usually at the lower current range where the efficasy is the greatest. For example, the Cree XM-L emitter which is the most efficient to date, shows a high lumen value of over 125 lumens per watt when driven at say 350 milliamps as spec'd. If that led was driven to it's max current 3Amp ( 3000 ma), then the lumen per watt figure would drop in a non linear fashion to around 65 to 75 lumens per watt. CRI is also something which I myself would prefer not to base my decision just by the high number alone. I have built/tested/prototyped led on-camera units using Cree's XP-G's and XM-L's in the lower CRI (80 to 85) range and discovered that they perform far better than others that claim over 90 CRI. Yes, I know there is a gap or discontinuous curve inherent in all leds as far as the color spectrum is concerned, but in my application as on-camera video lights, I find it negligible and my priority is face colors and white objects as rendered as white. One can be picky as far as perfect colors, but the end product must always be viewed on a lcd/tube/led monitor or telly. How are those colors adjusted by the viewer??. We are our own critics when it comes to perfection. I have done many weddings, and trust me, the bride really wants her dress to show the true shade of white and face colors to be right on. The led units I made are 3200K 85 CRI and awaiting for the soon to be released 90+CRI of the newest versions. I doubt the 90+ CRI's will show better whites or reds, but whatever the improvement will probably be minor. If one really wants a continuous spectrum, then perhaps for now the tungsten filament along with it's power hungry requirements is the way to go unless one wants to wait for the LEP's to appear in the future. I can understand the multitude of led units that display the green spike as being of the cheap
mass produced, disposable units, but one gets what one pays for. Led emitters have improved dramatically over the past couple of years, but most manufacturers still opt to use the multi led panel arrays. Specs of course will always be exagerrated by many mfr's, but thorough side by side comparisons and honest photometric evaluation would be welcome in the final decision of choosing. Let the best lamp win.
Thread: ECO Punch PLUS LED Light
Results 11 to 15 of 15
07-01-2012 10:46 AM
07-13-2012 06:36 AM
Darren, all things pertaining to LED's, technical, custom mods, newest available and retrofitting etc. can be found best by being a member of CPF ( CandlePowerForums ). I am a member there and it is a treasuretrove of information.
Check out their special application lighting section where you can get fast answers by knowledgeable members ( they have leds in their blood). You do not have to be a member to browse but it's free and well worth it.
Have you seen the new Cree XPG-2's and the MTG-2 ? now that's what I'm talkin' about.
07-14-2012 11:53 AM
- Join Date
- Aug 2004
- Hollywood, USA
With the claim that this light is more powerful than a 2500w hmi it would seem that its a huge breakthru for LEDs. Its also cheaper, lighter(no ballast), draws far less power, built in dimmer, and no bulbs to replace. Keeping in mind that this the first LED of this size, the future looks pretty interesting in lighting.
07-14-2012 05:04 PM
Leds, and he most efficient out there are really around 6 X more efficient than the common filament bulb. Beam angle is the determining factor ( and most often misunderstood) that ups the lux/lumen/fc/brightness/intensity/
value by a HUGE margin. The more the beam narrows, the brighter the light at that lit surface. Notice the photometric fc (foot candle) value at 10 feet. Over 4000 fc's. Wow and good, BUT what is the beam angle when that was measured ????. I would say very narrow or spotty and 5400K or bluish at that. Notice also the FC value at the SAME 10 feet distance gets cut down to size when the beam is widened up a bit to a more commonly used 55 degrees ( flood, diffused, key or main light) to a value of 216 FC. A big drop from 4000+ FC's at the narrow end of it. Now take that 216FC at 10 feet and try on a 3200K gel/filter on for size and you will end up with around 140 FC at best. 140FC's at 10 feet is approximately (140/.092 ) or 1521 luxes. Those 1521 luxes at the standard ( if a standard exists at this point in time) 3 feet or 1 meter distance, roughly equates to 18000 lumens. That would be in the area of a 1200 watt tungsten unfrosted filament. The filament would draw 1200 watts of power and the led ( for the SAME color temperature and beam angle) would draw 4.8 amps( on the specs) X 120V AC (they didn't mention at what voltage but I assume at 120 AC) = 576 watts. Slightly less than half power draw from a filament. Just comparing apples to apples. Sure, I would imagine that it is more powerful( light intensity wise) than a 2500W HMI, as long as that HMI must have (or be measured at) the SAME narrow beam angle of the LED without ang filtration or diffusers. Hmmm. my .02 as usual..