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    Forza 500 (500w LED) vs. Profoto 1200w HMI
    #1
    Senior Member Grug's Avatar
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    Hey gents,

    So I tested the Forza 500 up against my Profoto 1200w HMI today, and figured some of you might be interested in the results.

    Long-story short? I was sadly underwhelmed by the output of the Forza.

    Colour-wise the Forza was very impressive. Effectively equivalent to the HMI bulb according to my spectrometer. And the beam from the LED is remarkably even too (evidently a COB has significant advantages over an open-faced point-source light in this regard)

    Output-wise however, there's clearly still no replacement for displacement. At 800 ISO and somewhere around 4-5 meters away from the lights (I didn't measure the distance, as I was only interested in comparative output), using a 50 degree Profoto Magnum reflector on the HMI (focussed to an evenly-spread beam), and the Forza's slightly tighter-beamed standard reflector, the numbers came in at:

    - Profoto 1200w HMI: f/11 + 2/10
    - Forza 500w LED: f/5.6 + 8/10

    So approximately a 1.5 stop advantage to the HMI (that's three times more output - you'd need three Forza 500s to match the output of the 1200w Profoto)

    Pairing the Forza up with it's Fresnel attachment (which works well, and has a pretty remarkable 45-10 degree range) I got:

    - Forza 500w LED @ 45 degrees: f/5.6 + 1/2
    - Forza 500w LED @ 20 degrees: f/8 + 6/10
    - Forza 500w LED @ 10 degrees: f/11 + 1/2

    Zooming the Magnum reflector on the Profoto in to create it's most intense hotspot (the hotspot being about twice the width of the Forza at 10 degrees - but the outer edges of the beam still spreading close to 50 degrees overall) I got:

    - Profoto 1200w HMI: f/22 + 8/10

    That's just a hair shy of f/32 (and with broad-beam reflector). With a tighter reflector that didn't lose as many lumens to the broader surrounding beam/spill those numbers would go up even higher.

    Which suggests to me that these higher-output COB LEDs are basically still on par with HMI on a lumens-per-watt basis. Now if we were comparing to an HMI fresnel, we'd lose around a stop to the lens, and there'd be less in it (maybe only half a stop). But compared to any open-face HMI (bug-lights like the K5600 Jokers or this Profoto of mine, or any Arrimax HMI like the M18) there's still a massive difference in output.

    I was kinda hoping there wouldn't be, so I could pick up the Forza 500 or the Aputure 600 and have all the output delights of the smaller HMIs, without the all bulb-blowing/5-minute warm-up times/and the joys of proper colour-shiftless dimming. But I fear we'll be waiting some time yet before we get there.


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    Thank you for the report.

    It aligns well with my guesses and the Aussie gaffers comment that his hmi is brighter bounced.

    There seems to be a load of dodgy bloggers who’ll don’t get theta focussed light is brighter than a spread one everything else being equal.


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    Senior Member Run&Gun's Avatar
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    Thanks for that, Grug. That matches up with my continued belief that none of the LED manufacturers are giving us a true HMI 1:1 equivalent replacement. They are all outputting less than the fixtures that the LED manufacturers are equating them to. Because I can tell you that my Nila Boxers are not equal to my Bron Kobold 800, even though Nila calls them equivalent to 800 watt fixtures.

    Even though this isn’t close to a 1200 like they claim, it could be decent(closer) for an 800. Probably a lot better than the Boxer’s, anyway.


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    Thanks Mark, great test. Sounds like the 600d will be more of a 575 PAR competitor?

    Which I think would still be huge if true.

    But what we really need is aputure's version of the Mole 20K...
    Last edited by rob norton; 05-28-2020 at 03:03 PM.


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    Senior Member Grug's Avatar
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    Quote Originally Posted by morgan_moore View Post
    Thank you for the report.

    It aligns well with my guesses and the Aussie gaffers comment that his hmi is brighter bounced.

    There seems to be a load of dodgy bloggers who’ll don’t get theta focussed light is brighter than a spread one everything else being equal.
    The number of tech videos I watch these days that I have to turn off after 5-10 minutes because it becomes apparent the host has no idea what they're talking about is kinda scary. There's just so much misinformation getting out into world because of it.


    Quote Originally Posted by Run&Gun View Post
    Thanks for that, Grug. That matches up with my continued belief that none of the LED manufacturers are giving us a true HMI 1:1 equivalent replacement. They are all outputting less than the fixtures that the LED manufacturers are equating them to. Because I can tell you that my Nila Boxers are not equal to my Bron Kobold 800, even though Nila calls them equivalent to 800 watt fixtures.

    Even though this isn’t close to a 1200 like they claim, it could be decent(closer) for an 800. Probably a lot better than the Boxer’s, anyway.
    Output definitely depends on the specific LED type. My remote phosphor LEDs for example, do seem to put out considerably more lumens-per watt than these COB LEDs can manage (but they also don't offer a fraction of the beam control the COBs do). But for COB LED vs. HMI it seems pretty close to 1:1 to me - so a 500w LED is going to be around a 575w HMI equivalent. Which is nothing to shake a stick at - 575w HMIs are super useful lights, and have enough output to do lots of things.

    It's just important that people understand what they're getting. If you're renting a Forza 500 to combat daylight or light night exterior (expecting, as I was, a 1200w HMI equivalent) you're going to be in for a rude surprise when you discover it's only about 35% of the output you were expecting.

    Quote Originally Posted by rob norton View Post
    Thanks Mark, great test. Sounds like the 600d will be more of a 575 PAR competitor?

    Which I think would still be huge if true.

    But what we really need is aputure's version of the Mole 20K...
    Yep, that's what I'm expecting now.

    Still fantastic. I've used the 300Dii a couple of times now, and that's a fantastic light, with very useful output. The 600D is going to be even more useful - just don't anyone start selling off their M18s anytime soon. There's still nothing else out there that's as useful (and won't be for some time to come).
    Last edited by Grug; 05-28-2020 at 07:51 PM.


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    Quote Originally Posted by Grug View Post
    Yep, that's what I'm expecting now.

    Still fantastic. I've used the 300Dii a couple of times now, and that's a fantastic light, with very useful output. The 600D is going to be even more useful - just don't anyone start selling off their M18s anytime soon. There's still nothing else out there that's as useful (and won't be for some time to come).
    Yeah the m18 is still so fast and simple. Having a tree of 4x 600ds would be annoying if that became a regular set up but I'd probably choose 3-4 600ds over one m18 if that was my buying situation. The answer is to still have access to everything and anything!

    Following the 1:1 logic, what will realistically take the m18 out of the equation? Is it just an aputure 1800d? I only mean from a functionality perspective, not sales that might've been generated by marketing hype. But you're right, it looks like this will take a long time to develop. Maybe by then arri will have a daylight only powerful COB light.

    If they made an aputure 1800d today and it cost 3x an aputure 600d, then it roughly comes in at the same price as an m18 anyway (in $AUD). It'll be like an m18 but with 0-100 dimming, app control, effects and who knows what modifiers, which sounds awesome.


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    Senior Member Grug's Avatar
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    Quote Originally Posted by rob norton View Post
    Yeah the m18 is still so fast and simple. Having a tree of 4x 600ds would be annoying if that became a regular set up but I'd probably choose 3-4 600ds over one m18 if that was my buying situation. The answer is to still have access to everything and anything!

    Following the 1:1 logic, what will realistically take the m18 out of the equation? Is it just an aputure 1800d? I only mean from a functionality perspective, not sales that might've been generated by marketing hype. But you're right, it looks like this will take a long time to develop. Maybe by then arri will have a daylight only powerful COB light.

    If they made an aputure 1800d today and it cost 3x an aputure 600d, then it roughly comes in at the same price as an m18 anyway (in $AUD). It'll be like an m18 but with 0-100 dimming, app control, effects and who knows what modifiers, which sounds awesome.
    If the 1:1 lumens-per-watt ratio remains, then yeah, it'll take an 1800w COB to compete. That would be a freaking awesome light though - with 0-100% dimming, you could use it for almost anything - where the M18 is purely a bash light.

    At 1800w though, I suspect the heat issues could possibly destroy your ability to use any kind of conventional Bowens mount adapters (like most of the COBs at the moment). You'd need much sturdier (and more expensive hardware).

    I guess the sad thing is, if 1:1 is as good a ratio as we can get between the two lighting technologies - then there goes the dream of a 4k HMI equivalent LED that you could plug into house power.

    To me, that was the real dream of the higher lumen-to-watt ratio that LEDs initially promised us.

    My suspicion (and this is total conjecture on my part) is that in order to not kill the LEDs in a COB with heat death, they have to scale down their per-watt output significantly - and that's where we're losing the more favourable output ratios.


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    Quote Originally Posted by Grug View Post
    If the 1:1 lumens-per-watt ratio remains, then yeah, it'll take an 1800w COB to compete. That would be a freaking awesome light though - with 0-100% dimming, you could use it for almost anything - where the M18 is purely a bash light.

    At 1800w though, I suspect the heat issues could possibly destroy your ability to use any kind of conventional Bowens mount adapters (like most of the COBs at the moment). You'd need much sturdier (and more expensive hardware).

    I guess the sad thing is, if 1:1 is as good a ratio as we can get between the two lighting technologies - then there goes the dream of a 4k HMI equivalent LED that you could plug into house power.

    To me, that was the real dream of the higher lumen-to-watt ratio that LEDs initially promised us.

    My suspicion (and this is total conjecture on my part) is that in order to not kill the LEDs in a COB with heat death, they have to scale down their per-watt output significantly - and that's where we're losing the more favourable output ratios.
    Maybe developments in other areas will get us there. For example, post production audio tools that can remove absolutely any sound will allow louder cooling systems which aren't even being considered at the moment. Except I bet it'd be tough to get a noisy machine over the line in the first place.

    Or electronic batteries with so much juice it doesn't matter how inefficient the light is? But at that point we may see a resurgence in all original inefficient lights.

    Sorry, didn't mean to derail the thread!
    Last edited by rob norton; 05-28-2020 at 11:10 PM.


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    The physics suggests strongly that while LED is now a serious contender in the brightness stakes against halogen traditional sources, HMI, CSI and MSR sources will be impossible to match let alone beat because they are arc sources - plasma, and the principal is so different that semiconductor production of photons of this intensity is with current technology, destructive. We are seeing bigger and bigger LED clusters, but the size of the heatsinks is growing larger out of proportion to the increased light output. We can take something like an Arri 1K Fresnel and get the same or greater light output from an LED design - but a discharge source like the HMI Arris is around 4 times the brightness for the same power consumption. The 500W Forza might be a replacement for some things the Arri 1K Fresnel does, but it's like comparing engines in a car. Cubic Capacity is no indicator at all of performance. My view of the brighter LED designs of all kinds is that many are bright, but few produce the 'quality' of light the old ones do. Has anyone tried to blend two or more LED fixtures to give an even crossover? With the old kit, you could stick up two or three Fresnels and the cameras showed few hotspots that you couldn't fix, and the brightness was remarkable even, with that nice feathering off of brightness at the edge. LEDs just don't do this. Especially those COB types where at best, you get microlense 'diffusers' on the front. It's like we've thrown away good lights and are lighting everything with the modern version of a redhead or blond - it's brute force, not delicacy. I nearly bought couple of Arri LED Fresnels but at the last moment didn't and I'm glad, because a year later, the new ones are nicer, and next years will be nicer still. I cannot buy products where their evolution is progressing so fast.

    HMI and the other discharge sources have loads of drawbacks - running cost and heat primarily - but the damn things are bright!


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    Senior Member Grug's Avatar
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    The beam from the Forza 500 and the Aputure 300Dii (which are the only COB lights I’ve used) are exceptionally even. More so than any fresnel I can remember. The beam looked almost Leko-like in its evenness from edge to edge. Obviously that can change depending on the modifier used. But they’re far more even than any open-face source I’ve ever seen.


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