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Whats the litepanel astra like to use?


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#1 andrew ward

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Posted 02 May 2015 - 01:56 AM

If its bi colour is 4 times brighter than an older litepanel, that seems pretty good.
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#2 Colin Elves_18850

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Posted 02 May 2015 - 03:04 AM

Yeah, it's good. Very bright.
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#3 Dan Finlayson

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Posted 02 May 2015 - 03:31 PM

Good light when diffused, subpar build quality - too much plastic.


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#4 Michael LaVoie

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Posted 02 May 2015 - 03:42 PM

I used one last week.  I liked it but found it a bit green for daylight use.  Also needs diffusion which if you don't have diff on frames, is odd to clip directly to the unit cause there are no doors.  At least not on the unit that was rented.   Maybe they forgot them.


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#5 Colin Elves_18850

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Posted 02 May 2015 - 03:47 PM

I don't think it has barn doors. I'd slam it through one of the diffuser discs you get in those 5-in-1 reflectors. If you're buying you should think about getting an airbox soft box: http://airboxlights.com


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#6 Guy Holt

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Posted 03 May 2015 - 02:56 PM

The new Astra 1x1s are a vast improvement over the old 1x1 Bicolor Litepanels.  They have a Television Lighting Consistency Index (TLCI) in the high 90’s, which means, according to the developer of the test,  that "their color rendering deficiencies are so small that a colorist would not consider correcting them."  By comparison, the old 1x1 Bicolor Litepanels tested had TLCIs in the mid 50’s, which means that a colorist would certainly want to correct the errors, and could probably achieve an acceptable result, but it would take significant time. For those not familiar with TLCI ratings, it is a means of analyzing the performance of a luminaire in the context of what color correction would be required for television broadcasting.

 

The new Astra 1x1s are also power factor corrected with a pf of .99, where the old 1x1 Bicolor Litepanels were not and had a pf of .62. What this means is that nearly 40 percent of the power consumed by the old 1x1 Bicolor Litepanels did not go into generating light.  With a near unity power factor, the new Astra 1x1s are much more efficient.

 

One problem I find with the Astra 1x1s is that, like most LEDs, their power factor decreases as they are dimmed. In tests I recently conducted with a number of LED fixtures, the pf of the Astra 1x1 dropped from .99 to .54 when dimmed 50% (use this link to see the complete results of my tests.)  

 

 

LED_Astra_Composite_Sm.jpg

(Bottom left dimmed 50%. Bottom right dimmed to 25%.)

 

This drop in efficiency is less worrisome than the harmonic currents it also draws when it is dimmed (see the Fast Fourier Analysis above.) The harmonic currents it draws are worrisome because they can affect portable generators adversely.

 

waveform_elec_ballast.jpg

(Left: Grid Power w/ 1.2Kw Arri non-PFC Elec. Ballast. Center: Conventional AVR Power w/ 1.2Kw Arri non-PFC Elec. Ballast. Right: Inverter Power w/ 1.2Kw Arri non-PFC Elec.)

 

Given the large sub-transient impedance of conventional portable generators, the generation of even a small degree of harmonic noise will result in a large amount of distortion in its’ voltage. Add to that, the fact that the original supply voltage waveform of conventional portable generators is appreciably distorted to begin with, and you have a situation where the generation of any harmonic currents, whether by non-PFC HMIs, Fluorescents, or LEDs will result in the significant waveform distortion of the voltage seen in the oscilloscope shot above which can lead to operational problems with the generator voltage and frequency regulation.

 

Guy Holt, Gaffer

ScreenLight & Grip

Lighting Rental & Sales in Boston


Edited by Guy Holt, 03 May 2015 - 02:57 PM.

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#7 andrew ward

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Posted 04 May 2015 - 01:21 AM

Thanks for the info guys!


Hey Guy, you should just put a link for your standard information. Im very interested in what you say and appreciate you taking the time, but surely it would save you time everytime you post similar education about pfc etc.

But thanks, i wouldnt be able to get that info anywhere else!
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