Newly used LED lighting

[Mark von Kanel]

Sorry Urban,

i didnt make myself clear, i ment could you recommend any CFL's im really not tha bothered about LED, we have been trying them on our boat and they are a total pain in the ass! ill wait until the tech develops a little more.

[Inkanyezi]

Sorry Urban,

i didnt make myself clear, i ment could you recommend any CFL's im really not tha bothered about LED, we have been trying them on our boa and they are a total pain in the ass! ill wait until the tech develops a little more.

Boa, do you refer to the reptile?

Then it is a particular case. You should not subject reptiles or birds to light from compact lamps, neither FL nor LED, because of the modulation. We had the problem in the Skansen Aquarium, where any modulated light, modulated by 100 Hz did not work at all. When the lights were changed to fluorescents driven by HF gear that was sufficiently smoothed, problems disappeared.

It seems as modulated light could be lethal to reptiles; destroyed their eggs.

Whether it is harmful (or not healthy) to humans is under debate.

[ajohnw]

I have noticed that the merchandise is different in different parts of the world, and here in Sweden I cannot get any other high quality LED bulbs than the 2700 K ones. They come as complete spotlights or as screw-in or E14 or E27 spots or replacement bulbs, as well as G10 socket bulbs for 230 V.

Cree makes several different power diodes, and they are retail marketed in Philips and Osram spots.

They are not dimmable, and most are Ra 80+.

There are also cheap spots of the bluish kind mentioned, which are not tri-phosphor, but blue emitters with yellow phosphor. That is the most common type in flashlights and in bicycle headlights. I abhor those lamps, which don't have a full spectrum.

It is very easy to test any LED flashlight for lack of red light, by directing it to any rear reflector of a vehicle. With the bad ones, it remains dark, but with a tri-phosphor lamp they light up bright red.

I haven't tried any dimmable ones, but I use a set of Northlight Loke for tabletop shooting.
http://www.clasohlson.com/uk/Loke-LE...ht/Pr182702000

Ikea sell a led type that has a very even illumination spot. Either with a base or clip on. A professional pointed me at them.

http://www.ikea.com/gb/en/catalog/products/00169659/

I looked for 2700K myself. They are about. I'd guess there is some concern about eye safety at higher K but I have conversed with people who spend hours staring down microscopes illuminated with them.

Might be of interest to some. There is a data sheet for a range on this page that shows the spectrum. They are normally sorted according to chromaticity groups for large scale users and looking at 2700K there is more variation probably because more light comes from the phosphors and currently that aspect isn't very controllable.

http://uk.rs-online.com/web/p/visible-leds/7319266P/

The yellow colouration isn't all that uncommon even on high spec power led's with 2 phosphors. Normal led's are different and I believe a range of blues are available. Looks like power led's can function more like those according to the data sheets on here. The RGGB one is of interest to me but for a different sort of photography.

http://uk.mouser.com/search/refine.a...&Ntt=682250274

Whoops I should add for high light levels the Ikea lights are really for macro photography type work not studio portraits but they are fairly camera friendly.
.
John
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[Mark von Kanel]

Never mind Urban, ill google it, thanks for you help.

[Inkanyezi]

Ooops Mark, boat, as in ship. How easy it is to drop a letter when typing.

[ajohnw]

Never mind Urban, ill google it, thanks for you help.

Not so easy in the UK Mark. No problem in the USA. The ones that are ideally needed are high cri 5000k types. In other words intended to give good D50 lighting as should be used for colour critical work. Even finding full sized tubes is a pain.

I thought SAD might help. It does seem to in the USA but it seems we must be sadder in the UK as they look to be 6400K or there abouts. Probably down to the yo yo's that sell them - bigger number so must be better. These are often described as continuous spectrum. They are sort of with spikes.

I did find some tubes eventually, very reasonably priced providing I bought 50 and that's why the retailers don't stock them - no call for them was the comment so people in the UK can't be sad.

I'd guess the only source is people who supply entire light stands with the bulbs but they don't seem very keen to say much about the bulbs fitted - more yo yo's.

John
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[Mark von Kanel]

Ooops Mark, boat, as in ship. How easy it is to drop a letter when typing.

Im heavily dyslexic and do it all the tim........

the spell checker is a god send, but i still dont see mistakes until ive read stuff several times

[Mark von Kanel]

Its actually proving harder than i thought to find anything with a cri stated, and some reviews say the manufacturers lie..... whod of thought eh?

i thought id be able to find a plate with holders, that would fit my existing soft box mount so that i could use all my exist modifiers with constant light. How wrong i was i cant even find any hight wattage cri rated lamps....

guess im going to be busy in my shed when i get home.....

[Inkanyezi]

Im heavily dyslexic and do it all the tim........

the spell checker is a god send, but i still dont see mistakes until ive read stuff several times

My challenges are other. As I am not an anglophone, writing stuff in English is really also somewhat painful.

But relying on spell checkers won't work, as long as the mistyped word is a real word, that fits in the sentence. Neither spell nor grammar checking would catch it.

For the boat, there are still not many nice fixtures around. As I have been making such lights in the past, my way would be first looking at the fixture, then adapting light to it in any suitable way. The easiest might be cannibalising some existing bulb, extricating the 230 V circuitry and replacing it with low voltage circuitry. The diodes themselves work at about 3.5 to 4 V and are essentially current-driven light sources. I would try some switching circuitry that provides constant current through the diodes.

The diodes themselves are easily dimmed by decreasing the current, and with a simple switcher, it can be regulated with a potentiometer.

Also a simpler circuit, just dumping excess voltage through a resistor is feasible, but not economic, as it consumes more than necessary. If that path is chosen, diodes should be connected in series. On 12 V it might be possible to connect three in series losing almost nothing. But I think that a current generator might be contrived with something as the Simple Switcher from Texas Instruments. There are also scores of other products from various manufacturers that can provide either a voltage or a current. For LED, you should primarily look for regulating current. http://www.ti.com/ww/en/simple_switcher/index.html

[fenix]

You guys are doing nothing but confusing me.

William, you're being fed a lot of old advice re: LED lamps. Myself I use nothing but a pair of 17W PAR38 3500K LED 60-deg floods for my bench-top work. No blue cast, no hue shifting, excellent diffused light, even without tracing paper, no 'spikey' spectrum, no burnt fingers.

Here's the spectrum - quite smooth, eh?



Image is from this independent lab test report:

http://kronometric.org/phot/lighting...38%20(015).pdf

Worth a look.

My rig:



The result:



Eric

[Mark von Kanel]

Eric, CIR 85 and your saying thats ok,? where as everybody else says we need above 90 now im confused as well as William...

[Colin Southern]

I'm going to bow out of this thread now, because I suspect that the topic is going to get over-analysed to death, to the point where people lose sight of the forest due to all the trees.

The bottom line is - for me anyway - "what do images shot with LED lighting look like?" From experience (backed up from what I've seen here) the answer is "b*oody awful". Yes - there may be variations that make a difference but, in my opinion anyway, it's still very much a case of "trying to make a silk purse from a sow's ear".

Good luck to those who try. Personally, I've "been there - tried that" - and won't be wasting any more time on it.

[Colin Southern]

William, you're being fed a lot of old advice re: LED lamps. Myself I use nothing but a pair of 17W PAR38 3500K LED 60-deg floods for my bench-top work. No blue cast, no hue shifting, excellent diffused light, even without tracing paper, no 'spikey' spectrum, no burnt fingers.

Here's the spectrum - quite smooth, eh?



Image is from this independent lab test report:

http://kronometric.org/phot/lighting...38%20(015).pdf

Worth a look.

My rig:



The result:



Eric

"Eric",

You must be sharing a work space with another (ex) member ...

Hello again, y'all . . .

Anticipating some resistance from a certain quarter to my posts, I retired to the shed to try a quick and dirty test.



Although the lighting was fairly even, the diffusers were a little small. Undaunted, I dug out the cheap lux-meter and found that, when it was close up to the paper, I couldn't read the stupid display. So, I had to settle for measurement at 10cm and 20cm - a doubling of distance which, according to some, should have 'quartered' the lux and which, according to others, should not have changed the lux at all. In practice the reading was about halved, which I attribute to the lux meter having a largish angle of view. Sadly inconclusive - must move to Japan . .

So, took a 'model' (Kodak white card) and tried it at the same distances:



Pointed a camera at it and set the exposure to 0 EV in each position. There was a difference. The light fell off by about 2/3 stops. But it did NOT fall off by two stops.

I am still talking about illuminance of the entire sensor from a large, evenly-lit area - so as make the point that illuminance at the sensor is NOT changed by distance under that particular circumstance and therefore that the inverse square law is not quite as universal as is claimed. I am NOT talking about some smaller item whose framing changes with distance - and that may be why my point is apparently not understood.

PS: A point source has no diameter. In my book, infinity times 0 = 0

PPS: can we stop using caps? My little finger aches from pushing the shift key

[ajohnw]

I'm going to bow out of this thread now, because I suspect that the topic is going to get over-analysed to death, to the point where people lose sight of the forest due to all the trees.

The bottom line is - for me anyway - "what do images shot with LED lighting look like?" From experience (backed up from what I've seen here) the answer is "b*oody awful". Yes - there may be variations that make a difference but, in my opinion anyway, it's still very much a case of "trying to make a silk purse from a sow's ear".

Good luck to those who try. Personally, I've "been there - tried that" - and won't be wasting any more time on it.

I agree Colin. I expected old advice to crop up at some point. Fine but nothing has changed. Ubran's advice to use low temperature ones is probably the best that can be given. They all show a fair amount of variation in the light emitted anyway. People play with colours so if they are happy with the results fine what ever they use.

What it boils down to is use them by all means but it's a well known fact that they wont show certain colours very well. Hence the interest in variants that use more colours than just single R G and B. It's also a fact that high cri types have to pump out a lot of blue. Not a good idea to look directly at these. People in some fields use this blue light to make things fluoresce as true UV high powered LED's are rather expensive.

Really fluorescent set ups using wide spectrum bulbs are a better option. Another might be HID, sometimes used in shops to give good colour rendition. Halogen is another option but mains voltage ones don't last long and for best results it needs to be filtered. Bulbs with that tend to be rather expensive. Best of all studio flashes. Too expensive for many. It looks like over run daylight tungsten is still available but cameras cope well with the ordinary sort..

After all we all love taking photo's lit by standard fluorescent lighting don't we. Some cameras even have several settings to try and colour balance them. They have similar problems to power LED's.

I found one link for me and Mark - just need to ask about the cri. There are also light unit sellers on ebay. Also bulbs from the US on there too on the UK site.

http://www.stevesphotoshop.co.uk/day...5000k_50w.html

I haven't waded through this site yet but understand they can be helpful

http://www.internationallamps.co.uk/

I forgot that I had a link to that site. Obvious place to look.

John
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[fenix]

"Eric",

You must be sharing a work space with another (ex) member ...

You don't give up, do you?

Yes, I was xpatUSA, aka Ted.

I get the message and am leaving again - this time for good.

[Colin Southern]

You don't give up, do you?

Yes, I was xpatUSA, aka Ted.

I get the message and am leaving again - this time for good.

It's YOU Ted / Eric / or whatever name you'll use to try and sneak back in with in another month who never gives up.

I'm really do hope you've "got the message". Frankly, you're hard work - and you end up wasting a lot of peoples time debunking the incorrect information you post.

So please - go argue with Jeff and Andrew on LL some more - or FM - or DPR. Anywhere but here.

[Mark von Kanel]

Thanks for the link John, ill check it out. Wescott sell a number of various different lamps that they claim are "daylight" 5400 but give no cri have you any experience with them?

I do actually have 2 ellinchrom rx 600 and 3 speedlights that i use for studio but i struggle when i trying product togging ive read that constant is the way to go and it seems inexpensive so i thought id give it a go if i can get the lamps!!

[Inkanyezi]

Thanks for the link John, ill check it out. Wescott sell a number of various different lamps that they claim are "daylight" 5400 but give no cri have you any experience with them?

I do actually have 2 ellinchrom rx 600 and 3 speedlights that i use for studio but i struggle when i trying product togging ive read that constant is the way to go and it seems inexpensive so i thought id give it a go if i can get the lamps!!

That's a problem with most of these lamps it seems. I got one of those spiral lights, and although reasonably good light quality, it does not blend well with natural daylight, as the 954 tubes do. It isn't really any big deal if they are the only sources of light, but I prefer the 954 lamps for mixed lighting.

The essence of my longish post #24 is that continuity of spectrum is not necessary, as neither the camera, nor our eyes, care for a continuous spectrum. My take on colour correctness of bulbs is that it is no big deal, as long as all colours are present to a sufficient degree. Then we may white balance and get reasonably good colour. The problem with the cheaper "white" diodes used in flashlights and some bike lamps is that they have insufficient red, like no red at all. It is a problem when riding a bike too, as they won't be reflected by tail reflectors of vehicles.

Neither studio strobes nor speedlights display a continuous spectrum. They are spiky, just as the FL tubes or LED. The reason they work for photography is that they have a suitable blend of the three primary additive colours, red, green and blue. Many of them, just as these FL compact lamps, won't blend well with daylight, unless filtered. The CRI of a daylight lamp in fact tells us how well the light might blend with daylight. The CRI for a lamp below 5000 K is indicative of how well it would blend with incandescent. When all lamps are the same type, preferably same batch, the CRI is not of great importance. So CRI is important when you use different sources, but not quite as important when using only one type. Then it is more a matter of all colours being present to a sufficient degree.

So my take is that you can use the low K household lamps, provided all sources you use are the same, and then white balance. Those bulbs have sufficient output of the three colours, and for tabletops you can mostly use a long exposure time, so you won't need much light.

I hope, that in a near future, manufacturers will declare the CRI of LED bulbs too. Presently it's hit and miss.

[ajohnw]

There is no problem getting 954 tube lights in the uk especially the compact types. 860 and similar seems to be popular for spirals. The only way I have found high cri spirals so far is to search amazon for 90+ cri in bulbs and lighting. They seem to favour 5400K. Plenty of studio / photo bulbs as well but no mention of cri. Many have positive reviews. I often look on amazon for that aspect and maybe buy from some where else - depends on price difference.


John
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[Mark von Kanel]

Thanks Urban / john, i understand the concept now.