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Mixing different LEDS: diffusion

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Hello group:

I currently own a LITEMAT 4 S2 and I want to accompany it with another light.  My first instinct was to get another LITEMAT to partner it up with.  However one gripe I have with the litemat is that its not as punch as I would like in certain situations.  I have come across a lot of videos on the aperture 300d mark 2 light and one has become available for sale.  So my dillema is which light to get.  If I were to get the APARTURE 300d will it void using the LITEMAT in the same shot since they are a similar quality of light?  One thing that has me thinking is I love to diffuse it with bleached muslin.  Does it matter what light you use as long as you use a similar material to light through?  I have a cinematographer magazine article where Lubezki claims that it doesn't matter what light you use in the end when your only going to be blasting them through diff.

 

Any help would be appreciated

Thanks

O.R

 

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Posted (edited)

Here’s my take:

The older LEDs had more distinct differences in color and quality, but now most reputable lighting fixtures are much closer in these areas, where most could be used on the same set and in the same scene (Usually for different purposes.) example, if the inventory  allows, I usually have the same brand for scene modeling, and same for backlight, and same for key, etc.

If combining for the same “source” - The diffusion will certainly help blend them together, especially if they’re covering the same area of the diff. However, you’re also talking about blending a natively soft fixture with a 300d, which can be hardish. Generally speaking, I can see how one would want the same type of optics blowing through the same diff to get consistent shadows (I certainly would).

Edited by Joseph Tese
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So a 300D diffused with a Lightbox and also going through diffusion wouldn't get me the desired effect?

 

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Bleached mus is probably the issue, it murders light, and depending on the source, it produces a mixture of hard light and soft light.  If you see a hot spot in the muslin, there will be some hard light coming through, personally I'm a fan of magic cloth, you have to try really hard to get a hot spot and it doesn't completely kill the unit.   Mus is kinda like silks, they sound freakin beautiful, "soften the light with a silk", but the fact is they are very inefficient at diffusing.  If the budget has some excess room, booklit through mus with big lights, but if the budget is tight,  you gotta make each foot candle count. I'd go double break 250 litegrid, or bounce off ultrabounce way before shooting through mus.

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Whatever lights you get, do a test with them and your camera.

I would make sure their white balance is similar Not every manufacturer sets daylight to 5600k. Some lights, like the Sokani X60 is at 6000k. This can be corrected with 1/8 or 1/4 CTO, but try to find matched fixtures so you're not always pulling out gels. Their product page would display the color temperature.

There is however a magenta/green balance can can be present. It's not common among reputable manufacturers. Quasar Science did have a magenta-shifted batch of tubes a year ago that I got a hold of. So there's always a possibility. If you do ever have it, they can be corrected with plus green or minus green gel. They come in strengths of 1/8th, 1/4, 1/2, 1. I've found that 1/8 and 1/4 seem to be where LED shift can lie, but I haven't used all LEDs ever made (I heard AnandTech Punch shifts green by a large amount).

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Posted (edited)

In my experience once you diffuse light it becomes difficult or impossible to tell what brand the source was. You are primarily concerned with the quality of the diffused light falling on the subject, so it becomes more about the diffusion material.

I have mixed tungsten fresnel from Arri, Mole and B&A on the same shoot and it's impossible to tell much of a difference except in output. The lights from some companies are simply more efficient and therefore brighter than others. But once it's all diffused I think it's a non-issue.

I have mixed 2 x Aperture 300D units with a cheap Godox 60D and in terms of diffusion it wasn't an issue, but the Godox is bluer and the CRI is not as good, so in some cases that was noticeable if you looked closely, but it was not a deal breaker.

The main problem with mixing LED lights from different companies is that the CRI / spectral output doesn't match cross the board. Also color temp can vary. 5600 is not the same from many lights. I believe this is less of an issue with the highest quality units, that have a high CRI. Having something like the Sekonic 700 Spectrometer around comes in really handy, so you can see what you are dealing with...

The cheap Godox that I bought on a whim certainly is inferior in terms of color rendition than the Aperture and I would avoid using it with my main lights, unless it was way in the background. And even then I would keep an eye on it to make sure that it was not producing a green spike etc. But in terms of diffusion it's a non issue. That's more about the diffusion material.

The other main advantage to sticking with one brand of LED lights is that if they all have the same spectral output you can correct for any deficiencies or tendencies to lean green / magenta easily and globally in the digital intermediate. If you need to correct for several lights with different spectral output in the same shot things become interesting when you try to compensate for that in Resolve, Baselight etc

It should be kept in mind that in the film days we did mix tungsten and HMI with Kinoflo that produced a noticeable green spike (I'm looking at you David Fincher...) unless you compensated for that with gels or a special filler (LLD?). And yet somehow we still managed to make pretty pictures. You just need to be aware of all the little quirks and know how to deal with them.

CML recently did a LED shootout. Interesting results.

https://www.cinematography.net/LED-Camera/LED-Camera-Index.html

 

Edited by Feli di Giorgio

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