50W 6000K LED Floodlight on Ebay for under £30 - To good to be true or a steal?

eveares

eveares

Joined
28 Jul 2012
Messages
1,351
Reaction score
55
Location
Surrey
Country
United Kingdom
I am well aware of low quality and dangerous LED flood lights that are sold on ebay having watched many of bigclives videos on YouTube.

I am after a couple of cheap bright daylight LED light for video film work as I find my existing 125W 5500K CFL's with their matching stands & umbrellas are a bit to bulky and fragile for on-the-go spare of the moment film work.

The ebay listing in question is here: http://www.ebay.co.uk/itm/LED-Flood...door-Garden-Security-PIR-Option-/330923413186

I noticed that while the listing advertises them as 6000K, the box in the picture for the 50W one suggests the light is Warm White and is rated 4500Lm rather than the listed 4750Lm.

Do you think this listing to good to be true? And if so, what would you recommend for a low budget (<£50 ) daylight LED film light.

Regards: Elliott
 
For film work you need constant light, many LED drivers use pulse width modulation to control the current through the LED element. This results in the LED element varying in brightness several thousand times a second. This is not a problem for the human eye which averages out the brightness. Photographic film 24 frames a second probably won't be affected but video cameras may produce images with uneven brightness or other visual effects.
 
bernardgreen said:
many LED drivers use pulse width modulation to control the current through the LED element. This results in the LED element varying in brightness several thousand times a second.
Click to expand...

Did not think of that, I tend to film at 25fps or more often these days at 50 fps.

I assumed that the LED driver in the units would operate at high frequency operating in the tens of Khz range and thus not affecting my camera, unlike old style CFL's/MV's (Yes I have used 80W MV lamps with 70W HPS Ballasts in the distant past.) that operate and refresh at the mains frequency.

What would you recommend?
 
my brother bought 4 from ebay and i wasn't impressed dont know the company 4x50w 12ft apart [4+4+4]should light like midday but it was more like 20-25 w
 
Did you click on the select buttons? Link showed £2.95 until you select size, colour, and temperature and then it states £28.95 which seems reasonable. I only take stills and I love LED lighting the fluorescent has bands of colour rather than the full spectrum given by the white LED. I have looked at high speed flash as I am normally stuck with 1/180 second with standard flash and to me the LED is a far easier method. I have not noticed any effects from the PWM controllers I am sure they are too high of a frequency to really affect my camera. But my all use focal plane shutters, not sure what would happen with electronic shutters?
 
ericmark said:
Did you click on the select buttons?
Click to expand...

Read the thread title - 50W for under £30, hence 50W for £28.95.

Maybe when I have some spare money I will buy one to test and inspect and then make a decision on whether to by another one.
 
As I said seemed a reasonable price. I did the same with the smaller LED lamp I bought. Got the lamp from Aldi but with quartz bulb then sent for a LED replacement tube and could have got the whole lot already in LED format from Lidi at less money. They are simply not expensive in the first place.
 
Have I missed something? Do not use a PWM current supply to the LED's as this can cause banding on the video, but OK to use a switch mode voltage regulator!
Now a switch mode regulator as the name suggests switches the power on/off and regulates the average by changing the mark/space ratio. But the pulse width modulated regulator as the name suggests by changing the mark/space ratio as it pulses (i.e. switches on/off) regulates the average.
It really does not matter if regulating voltage, amperage, or watts it uses the same method. Only way to remove pulses is to use a battery or capacitor across the output.
Using the old bi-polar transistors you can make a power supply which is smooth, but the real point is quality of the power supply, in early years of the switch mode power supply they would not work with radio transmitters as they we too slow to respond to the quick rise in amps when switched to transmit. However today switch mode power supplies can react much faster and most transceivers use switch mode power supplies today.
As to what putting a capacitor across the output will do to the PWM controller I don't know. Adding to some one else's design is a problem as you are not sure how it samples the output and if capacitor will upset the balance.
As to construction method well my tripods would not like that weight. I carry my tripods on most trips, so being light is important. You would need a tripod designed for a plate camera to take that weight.
 
You must log in or register to reply here.
Back
Top