L.E.D lighting

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realspeed

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Don't know if this is of any interest but maybe worth considering

I fitted a Security L.E.D light (50w) to the side of my place and had a thought that this might be an idea for studio or photographic lighting for the cost of £85. No reason why it could not be fitted to a dolly with 240 v power

9ytr.JPG


Your thoughts???
The orange glow is from another "ordinary 400w security light so please ignore.
 
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The issue would be inability to turn the output down or fit any sort of modifier. I might get one for my drive though as I've already converted all my GU10 down lighters.
 
Worth considering. Incidentally that's where I got all of my led lamps from, have found the quality of the products to be excellent, as is the customer service.
 
there was some discussion about these on reduser or one of the other film forums out there - meant to actually be ok as a bucket of light actually. I seem to remember that they even tracked down one supplier that was able to give them a 5600k emitter one that was also pretty stable in terms of output - others may vary.
 
The AMOUNT of light will probably be just about adequate at high ISO, assuming that it's close to the subject. A 50W LED is roughly equivalent to a 500W halogen,

But there the difference ends, because the LED light has a discontinuous colour spectrum and despite whatever may be said about the CRI value, it will produce a green light that can be filtered out, but it still won't contain the necessary magenta element. And of course the light will be very harsh and uneven and will require a lot of diffusion - this will spread the light around and reduce its effective power dramatically.

There are special LED lights, designed specifically for photography, that address these problems, which is why they cost a lot more than security lights.
 
My photo didn't produce any green light as seen above and have not come across the issues raised even about distance. I am not disputing what you are saying but with the white light version I purchased may be different to the one you are referring to. Ok I purchased it for security reasons and as I said in my OP its just a thought for others to think over.
I do note Garry you have a connection with Lencarta lighting so have far more knowledge about the subject than myself.

For someone like myself I would explore every other means of lighting before spending out on expensive specialist photographic lighting which may or may not be any better Even using filters or diffusers would still be loads cheaper. Lower wattage L.E.D security lights would even be far cheaper
Link

http://www.lencarta.com/lighting-store/continuous-lighting/led-1000

Cost £400 for 100w output (see link) my security lighting for same out put using 2x50w lights £180 giving more chance of setting up lighting in 2 different positions for under half the price of Lencarts single version which still need addons for particular needs.

of course I recognise that professional photographers specialising in studio work would want specialist lighting but for the one off occasional amateur photographer may not want to spend that kind of money initially and my suggestion could be an alternative
 
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This what Garry means http://www.continental-lighting.com/lighting-basics/color-spectrum-light.php Google just brought that up, and not all LED lights will be exactly the same for sure, but the graph clearly shows big deficiencies, particularly at the red and violet ends.

Ideally, the graph should be almost flat, with all colours equally represented from 400K to 700K - the visible spectrum. The problem with peaks and troughs means that not all colours will be shown accurately, and this cannot be corrected. It may look pretty good to the naked eye, will probably look okay for a lot of photography, but not for critical work where colours have to be accurate.

It would be interesting to photograph a colour test chart (eg Macbeth) in daylight and then under the LED. Colour correct them in post processing so that mid grey is shown as neutral, then see how the colours compare. If you have a go at that, it would be interesting to see what you get :)
 
Too technical for me and I don't have a proper colour test chart Richard. But yes seeing how light is defined differently under various L.E.D lighting conditions as you mentioned would be interesting. Maybe someone else would have a go. Even doing that peoples colour vision is not the same for everyone which also has to be taken into consideration. Test charts/graphs etc can give technical details accurately but humans arn't the same and sees things differently
 
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Garry Edwards said:
There are special LED lights, designed specifically for photography, that address these problems, which is why they cost a lot more than security lights.
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This is the difference between the LEDs used in litepanels, manfrotto and all the other higher end led lights compared with the cheapest Chinese eBay offerings.

If I remember correctly the lightpanel LEDs are around 40-50 times more costly to buy than your standard LED
 
jacob12_1993 said:
This is the difference between the LEDs used in litepanels, manfrotto and all the other higher end led lights compared with the cheapest Chinese eBay offerings.

If I remember correctly the lightpanel LEDs are around 40-50 times more costly to buy than your standard LED
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Yes, that's about right. I visited one of the top names in Shenzen (China) recently and saw the capabilty of the very best of their products, they were amazing...

By contrast, the "affordable" light panels sold for photographic use just use domestic-grade LED's, and their performance is dire.
Too technical for me and I don't have a proper colour test chart Richard. But yes seeing how light is defined differently under various L.E.D lighting conditions as you mentioned would be interesting. Maybe someone else would have a go. Even doing that peoples colour vision is not the same for everyone which also has to be taken into consideration. Test charts/graphs etc can give technical details accurately but humans arn't the same and sees things differently
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Different people have different perceptions of colour, but the differences in colour rendition between the best and the worst of LED lighting is so extreme that there can be few people who won't notice when red comes out looking yellow:)
 
Garry Edwards said:
Yes, that's about right. I visited one of the top names in Shenzen (China) recently and saw the capabilty of the very best of their products, they were amazing...

By contrast, the "affordable" light panels sold for photographic use just use domestic-grade LED's, and their performance is dire.
Different people have different perceptions of colour, but the differences in colour rendition between the best and the worst of LED lighting is so extreme that there can be few people who won't notice when red comes out looking yellow:)
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Having held a range of these LEDs from low to high end next to each other, I can verify Garry's point that it is so extreme that it is easily visible with the naked eye.
 
Higher end companies will buy the inner bin LED chips
Lower end = outer bins

cheap LED's are cheap for a reason and I wouldn't fancy using them for photography. Inner bins have much better colour consistency
 
Not a good idea. As others have pointed out there will most likely be colour issues, and whats more those colours will change as time goes on.

Plus even if you team this up with a regulater to adjust the voltage supply to give you some kind of brightness adjustment the colour will change with the brightness.

A while back I needed to shoot something that actually had small perfectly white LEDs in the shot, rather than using them for shooting. I tried so many different cheap options, torches, bike lights all sorts of things. They were not only different colours I even got different colours between different examples of the same product by the same manufacturer and the colours changed as the batteries went flat.

In the end I brought some decent dedicated Manfrotto lights. No problems at all.

And I still used proper studio strobes to light it all.

Paul.
www.photographybyriddell.co.uk
 
Does anyone know, do LEDs flicker at all?
 
HoppyUK said:
Does anyone know, do LEDs flicker at all?
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Certainly no battery ones that I've used, and I don't think that that would change with mains power.

Fine for filming slo-mo, I've never had any flicker from LEDs on alexa/epic/fs700 shoots with slomo
 
itsdavedotnet said:
Certainly no battery ones that I've used, and I don't think that that would change with mains power.

Fine for filming slo-mo, I've never had any flicker from LEDs on alexa/epic/fs700 shoots with slomo
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Thanks :)
 
riddell said:
Plus even if you team this up with a regulater to adjust the voltage supply to give you some kind of brightness adjustment the colour will change with the brightness.
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That's not how LEDs work.

In an LED an electron drops from an excited state to a normal state and emits light.

You either have a high enough voltage to excite electrons or you don't.

The way LEDs are dimmed is by pulsing them and varying the "off" time.
 
£85? for about £150 my mate bought a set of 3 studio lighs (new from ebay) they came with stands, decent size soft boxes the lot, and they are supprisingly powerfull, he's using them every day in his studio, no problems. I've tried then and to be fair I was expecting rubbish, but they really are good. Even on full length shots with the soft boxes I can get F22 easly (not that I'd want to) so shed loads of power.
If I was in the market I'd grab a set.
 
jacob12_1993 said:
Research can tell you a lot but experience can tell you even more and I'm pretty sure Dave is speaking from experience of using these on high end video/film shoots
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So am I. LEDs flicker and are colour unstable at slow mo speeds.
 
st599 said:
Not true. Latest research shows that for slow-mo, not only do many major brands of LED panel flicker, but they produce different colours in each frame. http://www3.ebu.ch/cms/en/sites/ebu/contents/knowledge/technology/news/201306/a-warm-welcome-for-the-ebus-led.html
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Very interesting, thanks for that. I haven't seen any problems, nor have a few DPs that I've talked to about it - but I'm certainly not one to argue with Mr. Roberts!

Will do some more reading... Exciting times with how fast LEDs are moving
 
st599 said:
So am I. LEDs flicker and are colour unstable at slow mo speeds.
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If an LED is driven from a stable DC source (which it should be) it will not flicker. A poor design using a switching regulator without any capacitance on the output might show some flicker in video. However, it is the function of the power supply, not inherent in the LED (if it exists at all).

The colour is a function of its chemical makeup and will not change.

For a look into the future of domestic and industrial lighting, have a look at this company which my company is making the flexible LED panels for: http://designledproducts.com/


Steve.
 
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Steve Smith said:
If an LED is driven from a stable DC source (which it should be) it will not flicker. A poor design using a switching regulator without any capacitance on the output might show some flicker in video. However, it is the function of the power supply, not inherent in the LED (if it exists at all).

The colour is a function of its chemical makeup and will not change.

For a look into the future of domestic and industrial lighting, have a look at this company which my company is making the flexible LED panels for: http://designledproducts.com/


Steve.
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They aren't driven from a stable dc source though.

The dimmable ones use pulse width modulation to dim. The colour temperature changing ones use pulse width modulation of the colour primary LEDs within the "white" LED to alter the colour.
 
That's clear then. LEDs don't flicker, except sometimes. And colour is stable, except for when it isn't :thinking:

swanseamale47 said:
£85? for about £150 my mate bought a set of 3 studio lighs (new from ebay) they came with stands, decent size soft boxes the lot, and they are supprisingly powerfull, he's using them every day in his studio, no problems. I've tried then and to be fair I was expecting rubbish, but they really are good. Even on full length shots with the soft boxes I can get F22 easly (not that I'd want to) so shed loads of power.
If I was in the market I'd grab a set.
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Do you know what they were Wayne? Link?
 
HoppyUK said:
That's clear then. LEDs don't flicker, except sometimes. And colour is stable, except for when it isn't :thinking:



Do you know what they were Wayne? Link?
Click to expand...

Not offhand but I'm going over to see him later so I'll check the make.
 
HoppyUK said:
That's clear then. LEDs don't flicker, except sometimes. And colour is stable, except for when it isn't
Click to expand...

The point I was trying to make is that LEDs don't inherently flicker. It's the power supply.

In much the same way as an ordinary bulb would flicker if you interrupted its supply. It doesn't mean that bulbs produce flickering light.


Steve.
 
Steve Smith said:
The point I was trying to make is that LEDs don't inherently flicker. It's the power supply.

In much the same way as an ordinary bulb would flicker if you interrupted its supply. It doesn't mean that bulbs produce flickering light.


Steve.
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Thanks Steve. Would I be right in saying then, that LEDs don't inherently flicker, but they can flicker when turned down, as that's one way of moderating brightness? Presumably there are other ways of adjusting brightness that don't flicker, or they wouldn't be nearly so useful for photography.

And colour, whatever it may be, doesn't change?
 
Steve Smith said:
The point I was trying to make is that LEDs don't inherently flicker. It's the power supply.

In much the same way as an ordinary bulb would flicker if you interrupted its supply. It doesn't mean that bulbs produce flickering light.


Steve.
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With respect, although I accept what you say, I think that the point here is that it's fair to say that the cheap ones do flicker and the ones that don't flicker aren't cheap.
 
HoppyUK said:
Thanks Steve. Would I be right in saying then, that LEDs don't inherently flicker, but they can flicker when turned down, as that's one way of moderating brightness? Presumably there are other ways of adjusting brightness that don't flicker, or they wouldn't be nearly so useful for photography.

And colour, whatever it may be, doesn't change?
Click to expand...

It depends on the controller. It is common to use a method called pulse width modulation to control brightness.

Imagine a circuit which turns the LED on and off 20,000 times per second. If the on time and off time are equal, the LED will put out half its maximum brightness. In order to vary the brightness, you adjust the ratio of on to off time. i.e 7% on and 93% off would be very dim and 88% on and 12% off would be near to maximum.

I don't think this high frequency flicker would be seen by the camera as even at 1/1000 second shutter speed, the camera would see 20 cycles of light. It's a bit like photographing a TV screen. You need a low shutter speed to get the whole image. If you run faster than 1/60 you get a partial image as the camera shutter is not open for a full scan. It's the same for the LED except that you would need a shutter speed of at least1/10000 sec before you see any flicker.

This is why I think it is the controller rather than the LED which caused the problem mentioned earlier. I suspect thart it was running too slow and would probably be tiring on the eryes too.

As for colour change when dimming. A white or other single colour LED will not change colour with brightness. However, if the white light is created by mixing red, blue and green LEDs then if the controller does not vary them equally, there could be some colour shift.

What I am really saying is don't judge all LED lighting by a not very well designed unit which has problems.

Have a look at the link I posted to see some ideas for domestic, industrial and architectural uses for LEDs in lighting.

LED is definitely the future of lighting. Compact fluorescents are just an interim technology.

As a side issue, our council is currently replacing sodium streetlights with LED lights. Each unit has 24 ultra bright white LEDs. The light is nicer as it's white rather than orange but the best thing about it is that there is not the horrible orange glow in the sky like you see over large towns now as all of the light is directed downwards. Also each lamp unit will now only consume about 2 watts compared with the 150 (ish) watts of a sodium lamp.

Also, at work we have a couple of LED car headlights. Each one has a single LED with a heatsink and their output can equal a bulb. Very expensive at the moment but the price will come down.


Steve.
 
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In my experience alone.... Battery powered led panels of any size, don't cause flicker at at least 240fps :) that is all, on the ones that I've used.... (Which ranges from eBay £30 hobbies to very expensive 1x1s)

I used to be on an electronic engineering course at uni... Quit to go and take pictures... :)

A rental house were showing off their new LED fresnels to me the other day... Some lovely kit starting to emerge.....
 
Curious to know what sort of F stop can be achieved with small LED lights. I do quite a bit of work for estate agents photographing interiors, and use speedlights (580ex's) with off camera triggers and gels. This approach gets me nice results with (smallish) domestic interiors, but is quite slow, and the job is time pressured.

I was looking on ebay and noticed these:

http://www.ebay.co.uk/itm/7dayshop-...pt=UK_Camera_Video_Lights&hash=item5aefd3c810

http://www.ebay.co.uk/itm/7dayshop-...pt=UK_Camera_Video_Lights&hash=item5aefd3c888

Must admit I am not a huge fan of continuous lighting (prefer flash) however I did wonder if using something like this would speed up the workflow. I don't know how they compare with flash as flash is rated by guide number whereas these seem to be rated in lumens. Obviously, the camera is on a tripod for this type of use.
 
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