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  #1   Report Post  
Howard
 
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Default Task lights

Advice required re LED's.

I currently use a lowvoltage 50 watt lamp at my bench
(jeweller), it's good light, a bit yellow and expensive to replace.

I have high hopes for LED's but before I change things around, I
thought it best to see if anyone has had real experience of them.
--
Howard
  #2   Report Post  
mrcheerful
 
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"Howard" wrote in message
. uk...
Advice required re LED's.

I currently use a lowvoltage 50 watt lamp at my bench (jeweller), it's
good light, a bit yellow and expensive to replace.

I have high hopes for LED's but before I change things around, I thought
it best to see if anyone has had real experience of them.
--
Howard


I find led light tiring.
I would use halogen lighting as its colour is like daylight.

mrcheerful


  #3   Report Post  
Howard
 
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mrcheerful . wrote:
"Howard" wrote in message
. uk...

Advice required re LED's.


I find led light tiring.
I would use halogen lighting as its colour is like daylight.


This is useful information.

I learn I need as full a spectrum as possible, tired eyes I do
not want.

Perhaps I should ask in uk.eyes ng. (?)

--
Howard
R100RT
Formerly James Captain, A10, C15, B25, Dnepr M16 solo, R80/7,
R100RT (green!)
  #4   Report Post  
Ian Stirling
 
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Howard wrote:
Advice required re LED's.

I currently use a lowvoltage 50 watt lamp at my bench
(jeweller), it's good light, a bit yellow and expensive to replace.

I have high hopes for LED's but before I change things around, I
thought it best to see if anyone has had real experience of them.


LEDs are basically probably not a candidate.
You're likely to be looking at some $200 plus for a light of a similar
wattage.
I'd look at fluorescant lights, there are a wide variety of colour
temperatures available.
And if you want, you can customise the colour temperature a bit - add some
blue card to the reflector, or yellow, ...

You want a high frequency ballast - flicker is bad.

  #5   Report Post  
Tim Mitchell
 
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In article , Howard
writes
mrcheerful . wrote:
"Howard" wrote in message
o.uk...

Advice required re LED's.


I find led light tiring.
I would use halogen lighting as its colour is like daylight.


This is useful information.

I learn I need as full a spectrum as possible, tired eyes I do not
want.

You don't get full spectrum with white LEDs. They are basically blue
LEDs with a fluorescent material to produce the white light. There are
lots of holes in the output spectrum.

Also it is unlikely you will get sufficient brightness. You'd need a
shed load of LEDs to rival the brightness of a 50W halogen.

I'd stick with your halogen lamp. You can get LV bulbs with built in
dichroic filters if you are concerned about the colour.
--
Tim Mitchell


  #6   Report Post  
Ian Stirling
 
Posts: n/a
Default

Tim Mitchell wrote:
In article , Howard
writes
mrcheerful . wrote:
"Howard" wrote in message
. co.uk...

Advice required re LED's.


I find led light tiring.
I would use halogen lighting as its colour is like daylight.


This is useful information.

I learn I need as full a spectrum as possible, tired eyes I do not
want.

You don't get full spectrum with white LEDs. They are basically blue
LEDs with a fluorescent material to produce the white light. There are
lots of holes in the output spectrum.


There exist 'warm white' LEDs, which don't do this.
  #7   Report Post  
Howard
 
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Ian Stirling wrote:
Howard wrote:

Advice required re LED's.

I currently use a lowvoltage 50 watt lamp


LEDs are basically probably not a candidate.


Thank you, I'm converted back again.


--
Howard
  #8   Report Post  
Tim Mitchell
 
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Default

In article , Ian
Stirling writes
Tim Mitchell wrote:
In article , Howard
writes
mrcheerful . wrote:
"Howard" wrote in message
.co.uk...

Advice required re LED's.

I find led light tiring.
I would use halogen lighting as its colour is like daylight.

This is useful information.

I learn I need as full a spectrum as possible, tired eyes I do not
want.

You don't get full spectrum with white LEDs. They are basically blue
LEDs with a fluorescent material to produce the white light. There are
lots of holes in the output spectrum.


There exist 'warm white' LEDs, which don't do this.


really, what manufacturer?

I thought that LEDs by their nature only produce a narrow spectrum of
light.
--
Tim Mitchell
  #9   Report Post  
Ian Stirling
 
Posts: n/a
Default

Tim Mitchell wrote:
In article , Ian
Stirling writes
Tim Mitchell wrote:
In article , Howard
writes
mrcheerful . wrote:
"Howard" wrote in message
r.co.uk...

Advice required re LED's.

I find led light tiring.
I would use halogen lighting as its colour is like daylight.

This is useful information.

I learn I need as full a spectrum as possible, tired eyes I do not
want.

You don't get full spectrum with white LEDs. They are basically blue
LEDs with a fluorescent material to produce the white light. There are
lots of holes in the output spectrum.


There exist 'warm white' LEDs, which don't do this.


really, what manufacturer?

I thought that LEDs by their nature only produce a narrow spectrum of
light.


They do.
It's just that some come with a fluorescant material with a wider spectrum.
Luxeon "Warm White" LEDs.
LEDs and fluorescants are basically similar - one uses blue, the other
uses UV to excite a mix of phosphor.
It's just that with the LED, the basic colour can be used as part of the light,
if desired.
  #10   Report Post  
Tim Mitchell
 
Posts: n/a
Default

In article , Ian
Stirling writes
Tim Mitchell wrote:
In article , Ian
Stirling writes

There exist 'warm white' LEDs, which don't do this.


really, what manufacturer?

I thought that LEDs by their nature only produce a narrow spectrum of
light.


They do.
It's just that some come with a fluorescant material with a wider spectrum.
Luxeon "Warm White" LEDs.
LEDs and fluorescants are basically similar - one uses blue, the other
uses UV to excite a mix of phosphor.
It's just that with the LED, the basic colour can be used as part of the light,
if desired.


Right, I have seen the luxeon ones. The light quality is still not that
great, I wouldn't want to use one as a work light as the OP wanted (even
if you could get enough to make it bright enough). The colour
temperature is quite variable from device to device, and also within the
beam of each LED.

I have no doubt that LEDs will get there for this application but they
aren't there yet.

--
Tim Mitchell


  #11   Report Post  
Ian Stirling
 
Posts: n/a
Default

Tim Mitchell wrote:
In article , Ian
Stirling writes
Tim Mitchell wrote:
In article , Ian
Stirling writes

There exist 'warm white' LEDs, which don't do this.

really, what manufacturer?

I thought that LEDs by their nature only produce a narrow spectrum of
light.


They do.
It's just that some come with a fluorescant material with a wider spectrum.
Luxeon "Warm White" LEDs.
LEDs and fluorescants are basically similar - one uses blue, the other
uses UV to excite a mix of phosphor.
It's just that with the LED, the basic colour can be used as part of the light,
if desired.


Right, I have seen the luxeon ones. The light quality is still not that
great, I wouldn't want to use one as a work light as the OP wanted (even
if you could get enough to make it bright enough). The colour
temperature is quite variable from device to device, and also within the
beam of each LED.


The "warm white" variant?
It's distinctly different, and really does look "warm white".
The normal one is slightly more efficient, and is more variable.
  #12   Report Post  
Chris Hodges
 
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Default

Ian Stirling wrote:
Right, I have seen the luxeon ones. The light quality is still not that
great, I wouldn't want to use one as a work light as the OP wanted (even
if you could get enough to make it bright enough). The colour
temperature is quite variable from device to device, and also within the
beam of each LED.



The "warm white" variant?
It's distinctly different, and really does look "warm white".
The normal one is slightly more efficient, and is more variable.


I've seen them, and the emission spectrum. I found them to approximate
tungsten lighting in appearance (though possibly a bit more pink). The
spectrum is similar to that of a normal white LED: a narrow peak in the
blue and a broad fluorescence peak centred in the yellow but with a fair
bit of green and orange-red. In the warm white this doesn't simply tail
off but goes up again a bit in the red before tailing off still sithin
the visible. Colour rendering (empirical, not technical use of the
term) is good, though less so at the shortwave end. The normal luxeons
aren't bad either.

The OP might be better off with an RGB array of LEDs (which is also more
efficient) as you can balance the colours, but that would be DIY(!)
and/or expensive.

--
Spamtrap in use
To email replace 127.0.0.1 with blueyonder dot co dot uk
  #13   Report Post  
Chris Hodges
 
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Default

Andy Dingley wrote:

On Wed, 16 Feb 2005 11:34:42 GMT, Howard
wrote:


I currently use a lowvoltage 50 watt lamp at my bench
(jeweller), it's good light, a bit yellow and expensive to replace.



Try a Luxo illuminated magnifier. There's a lot around cheap at
present, they have a "daylight" circular fluorescent in them, and
there's a flap over the top to cover the magnifier and make them into
a simple worklight. Nice long-reach arms too.


They're nice. But not very daylight compared to either daylight or a
daylight tungsten.

--
Spamtrap in use
To email replace 127.0.0.1 with blueyonder dot co dot uk
  #14   Report Post  
Dave Plowman (News)
 
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Default

In article ,
Howard wrote:
I currently use a lowvoltage 50 watt lamp at my bench
(jeweller), it's good light, a bit yellow and expensive to replace.


I use a 100W mains halogen. Quite good, colour wise. Although so should a
suitable LV one be. Has a life of about the same as most bulbs - 1000
hours - if not knocked.

I have high hopes for LED's but before I change things around, I
thought it best to see if anyone has had real experience of them.


Present LEDs are not continuous spectrum light which I'd think might
matter for your work.

--
*If we weren't meant to eat animals, why are they made of meat?

Dave Plowman London SW
To e-mail, change noise into sound.
  #15   Report Post  
Ian Stirling
 
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Chris Hodges wrote:
Ian Stirling wrote:
Right, I have seen the luxeon ones. The light quality is still not that
great, I wouldn't want to use one as a work light as the OP wanted (even
if you could get enough to make it bright enough). The colour
temperature is quite variable from device to device, and also within the
beam of each LED.



The "warm white" variant?
It's distinctly different, and really does look "warm white".
The normal one is slightly more efficient, and is more variable.


I've seen them, and the emission spectrum. I found them to approximate
tungsten lighting in appearance (though possibly a bit more pink). The
spectrum is similar to that of a normal white LED: a narrow peak in the
blue and a broad fluorescence peak centred in the yellow but with a fair
bit of green and orange-red. In the warm white this doesn't simply tail
off but goes up again a bit in the red before tailing off still sithin
the visible. Colour rendering (empirical, not technical use of the
term) is good, though less so at the shortwave end. The normal luxeons
aren't bad either.

The OP might be better off with an RGB array of LEDs (which is also more
efficient) as you can balance the colours, but that would be DIY(!)
and/or expensive.


I have R/G/B 38W fluorescant lights, that I still mean to make into a
variable colour lighting fixture.


  #16   Report Post  
Dave Plowman (News)
 
Posts: n/a
Default

In article ,
Andy Dingley wrote:
I currently use a lowvoltage 50 watt lamp at my bench
(jeweller), it's good light, a bit yellow and expensive to replace.


Try a Luxo illuminated magnifier. There's a lot around cheap at
present, they have a "daylight" circular fluorescent in them, and
there's a flap over the top to cover the magnifier and make them into
a simple worklight. Nice long-reach arms too.


These IMHO don't give the same illumination as a 50 watt LV halogen, and
aren't decent tubes, colour wise.

I also like the quartz-halogen bulbs that fit into a standard bayonet
lampholder - around 150W (sorry, can't rememeber the name). Too big
for a desk lamp, but they're a nice workroom light and the colour is
pretty good.


My choice. Early ones didn't seem to last, but seem to have got better.

--
*Corduroy pillows are making headlines.

Dave Plowman London SW
To e-mail, change noise into sound.
  #17   Report Post  
Pete C
 
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Default

On Wed, 16 Feb 2005 11:34:42 GMT, Howard
wrote:

Advice required re LED's.

I currently use a lowvoltage 50 watt lamp at my bench
(jeweller), it's good light, a bit yellow and expensive to replace.

I have high hopes for LED's but before I change things around, I
thought it best to see if anyone has had real experience of them.


Hi,

Try 2, 3 or 4 20W desktop halogens, cheap as chips! :

http://www.argos.co.uk/webapp/wcs/stores/servlet/ProductDisplay?storeId=10001&langId=-1&catalogId=3151&productId=121777&clickfrom=name

cheers,
Pete.
  #18   Report Post  
Tim Mitchell
 
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Default

In article , Ian
Stirling writes
Chris Hodges wrote:
Ian Stirling wrote:
Right, I have seen the luxeon ones. The light quality is still not that
great, I wouldn't want to use one as a work light as the OP wanted (even
if you could get enough to make it bright enough). The colour
temperature is quite variable from device to device, and also within the
beam of each LED.


The "warm white" variant?
It's distinctly different, and really does look "warm white".
The normal one is slightly more efficient, and is more variable.


I've seen them, and the emission spectrum. I found them to approximate
tungsten lighting in appearance (though possibly a bit more pink). The
spectrum is similar to that of a normal white LED: a narrow peak in the
blue and a broad fluorescence peak centred in the yellow but with a fair
bit of green and orange-red. In the warm white this doesn't simply tail
off but goes up again a bit in the red before tailing off still sithin
the visible. Colour rendering (empirical, not technical use of the
term) is good, though less so at the shortwave end. The normal luxeons
aren't bad either.

The OP might be better off with an RGB array of LEDs (which is also more
efficient) as you can balance the colours, but that would be DIY(!)
and/or expensive.


I have R/G/B 38W fluorescant lights, that I still mean to make into a
variable colour lighting fixture.


You get orrible coloured shadows if you do this (with any discrete
sources of R G and B), unless you are a long way from the object being
lit. It is also pretty much impossible to get any decent sort of white.
(I've designed several colour mixing fixtures for people, both
fluorescent and LED, and all suffer from this problem).
--
Tim Mitchell
  #19   Report Post  
Ian Stirling
 
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Default

Tim Mitchell wrote:
In article , Ian
Stirling writes
Chris Hodges wrote:
Ian Stirling wrote:
Right, I have seen the luxeon ones. The light quality is still not that
great, I wouldn't want to use one as a work light as the OP wanted (even
if you could get enough to make it bright enough). The colour
temperature is quite variable from device to device, and also within the
beam of each LED.


The "warm white" variant?
It's distinctly different, and really does look "warm white".
The normal one is slightly more efficient, and is more variable.

I've seen them, and the emission spectrum. I found them to approximate
tungsten lighting in appearance (though possibly a bit more pink). The
spectrum is similar to that of a normal white LED: a narrow peak in the
blue and a broad fluorescence peak centred in the yellow but with a fair
bit of green and orange-red. In the warm white this doesn't simply tail
off but goes up again a bit in the red before tailing off still sithin
the visible. Colour rendering (empirical, not technical use of the
term) is good, though less so at the shortwave end. The normal luxeons
aren't bad either.

The OP might be better off with an RGB array of LEDs (which is also more
efficient) as you can balance the colours, but that would be DIY(!)
and/or expensive.


I have R/G/B 38W fluorescant lights, that I still mean to make into a
variable colour lighting fixture.


You get orrible coloured shadows if you do this (with any discrete
sources of R G and B), unless you are a long way from the object being
lit. It is also pretty much impossible to get any decent sort of white.
(I've designed several colour mixing fixtures for people, both
fluorescent and LED, and all suffer from this problem).


There is no reason that they have to be.
It's just that the needed diffusing optics are bulky, and a bit annoying to
design.

As to being impossible to get a decent white, I suspect you may be right -
only three phosphors doesn't help, or the relative low power of the red tube.
  #20   Report Post  
Tim Mitchell
 
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In article , Ian
Stirling writes
Tim Mitchell wrote:
In article , Ian
Stirling writes
Chris Hodges wrote:
The OP might be better off with an RGB array of LEDs (which is also more
efficient) as you can balance the colours, but that would be DIY(!)
and/or expensive.

I have R/G/B 38W fluorescant lights, that I still mean to make into a
variable colour lighting fixture.


You get orrible coloured shadows if you do this (with any discrete
sources of R G and B), unless you are a long way from the object being
lit. It is also pretty much impossible to get any decent sort of white.
(I've designed several colour mixing fixtures for people, both
fluorescent and LED, and all suffer from this problem).


There is no reason that they have to be.
It's just that the needed diffusing optics are bulky, and a bit annoying to
design.

As to being impossible to get a decent white, I suspect you may be right -
only three phosphors doesn't help, or the relative low power of the red tube.


The commercial fluorescent colour changers include a white tube (plus
RGB) to get round it. A lot of the LED fixtures are being changed to
include amber LEDs for the same reason.
--
Tim Mitchell
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