LEDs


Many LED luminaires do not use high frequency drivers to eliminate flicker in the same way high frequency fluorescent lamp ballasts eliminate flicker. Shooting video in environments with  a lot of LED luminaires can produce video with distracting flicker. Viewers do not want to be distracted, and will switch off  if they see annoying flickering.

LED Lighting Video Recording Tips?

To eliminate flicker, for 120V 60Hz locations, the best shutter speeds to use are at multiples of 120, while at 220/230V 50Hz power locations, best shutter speeds are in multiples of 100. This Telegraph video seems to have been shot at 25 fps, which may be why a lot of annoying flicker can be seen. For flicker free video in 50Hz electrical environments, shooting at 50 or 100 fps should give best flicker free results, for 60Hz, 60 to 120 fps should give best results

For 50Hz 1/100, 1/50, 1/33, 1/25. 50 & 100 fps should = best results
For 60Hz 1/120, 1/60, 1/40, 1/30. 60 & 120 fps should = best results

This video should most likely have been recorded at 100 fps or 50 fps. In post-production there is no fix for this strobing effect. The only solution is to test other camera settings & re-shoot.

A best approach when Designing Architectural Lighting is to specify LED luminaires with high frequency, flicker free dimming drivers.

See full video & Telegraph article here: http://bit.ly/1cvuZxH

 There seems a mad rush to use blue light in your Fridge.

FrigdeSmallPic

A new stainless steel fridge might look nice in your kitchen, but open the door.

What do you see? Is this what food looks like on your kitchen counter or table?

Is this what the food looked like when you bought it?

Light, and the colour of light, affects how we see the environment around us.

Do you want to see food that looks artificially cold, or do you want to see food in the correct light?

The purpose of fridge lighting is to communicate information; we need to see food, and its colour, to decide if it is healthy to eat.

Does a steak look blue, grey, or red fresh and ready to cook & eat? The colour of food helps tell us if is healthy to eat. Is opening your fridge a pleasurable experience?

Can you see everything? Does the food look good? What can you see?

LEDs can provide excellent optical control of light beams in low profile housings. Fridge interior area lighting may be improved with multiple low profile LED lights vs. past methods that used a single fridge lamp.

LED lighting does not have to have poor colour rendition. It is possible to have correct and accurate colour LED lighting in fridges.

Does the food in your supermarket refrigerator case look correct? Much supermarket food is now being lit with linear strip LED lighting. Custom LED lamp phosphor blends can offer accurate colour lighting.

What do you see inside these fridges? Does this look like food you want to eat?

Could fridge interior blue light imply a false sense of food temperature & appearance?

Will blue colour light make you think food is cold, when the fridge is off?

Does fridge lighting make food look like un-ripened fruit that should be left to ripen, but due to colour appearance might be left to rot?

Accurate light colour rendition seems a common sense consumer protection safety issue.

Should a 2000 dollar fridge come with a 2 dollar light?

Fridge interior visual design experience is important, as is accurate and well placed glare free lighting. Fridge manufacturers need to invest in more in how and what consumers see, to meet expectations, and ensure food safety.

There are standards for lighting colour quality.

Do consumers need protection from poor quality lighting colour? Yes they do.

A global view of the food we eat  look & listen to NPR’s review of the book,  ‘Hungry Planet: What The World Eats’   Photographer Peter Menzel and writer Faith D’Aluisio visited 30 different families around the world noting the food they eat

Many candelabra lamps look nothing like the candle flames they replace.

What a shame.

Good lighting provides the ‘lean forward moment’ found in film. The visual impression should be one of invitation, enjoyment and appealing appearance of space.

Too often candelabra lamps are nothing like the flames they replace.

Older style Incandescent candelabra lamps needed larger exterior glass envelopes to prevent the lamp glass from melting due to filament heat. Unfortunately many seem not to have understood the reason for this lamp construction solution and kept this larger, not to scale lamp size. It seems often fluorescent and LED sources are placed inside plastic large format candelabra lamp format envelopes…resulting in nothing but unsightly hideous glare bombs.

Good Lighting invites the viewer to enjoy the created space. Chandeliers essentially are  best only as decorative lighting. Attractive artistic shapes is what they can offer.

A dark, light story:

Ritz-Carlton Central Hong Kong.  Opened 1993. Demolished 2008.

A story told was the Interior Designer decided to be the Lighting Designer and essentially only used Chandeliers to light the hotel. The main lobby was dark & dreary and the room occupancy always low. A five-star hotel should never have had dark brooding lobbies and public circulation spaces. Overly bright chandeliers became glare bombs.  The best part of the hotel was the Health Club which had lighting designed by Tony Corbett. You could see the difference.

Lighting Design is all about what you want to see and how you want to see it. It has been said there are only three kinds of lighting. Bad Lighting which is obvious. Indifferent Lighting which while it may be technically correct, is uninspired, and Good Lighting invites the viewer to want to walk into a space to enjoy the created environment.  The viewer feels the instantaneous sensation of the film ‘lean forward moment’ and is compelled to enjoy the created space.

In 1975 Ingmar Bergman filmed the Magic Flute in the Drottningholm Palace’s 17th century Theatre.

Many years ago I traveled to see this Theatre and the chandelier candle replacement lamps. The candelabra lamps wobble independently mimicking the appearance of flames. Magic. You were instantly transported back in time, the created environment of the theater felt much the same as it would have had all chandeliers been lit with candles, but without the smokey smell smog.

This video compilation shows this unique lamp and heritage space. Seeing moving incandescent flame size lamps, was a magical experience.

Drottningholm Court Theatre Chandeliers

Unfortunately I have yet to see any decent LED chandelier candle replacement lamps which mimic the friendly flicker of flames…

Babies undergoing phototherapy for hyperbilirubinemia, have eye masks to prevent risk of UV exposure and to eliminate risk of retinopathy of prematurity. Lights in neonatal wards are not allowed on 24 hours a day. Direct & bare lamp use is not allowed.

Phototherapy lamps used have a special phosphor coatings only for bililights. As an added precaution the bililights I designed use a museum quality acrylic UV filter.

Newer medical research indicates a slight shift in action spectrum may speed photo therapy. LEDs can be used for this phototherapy. Much research has found them to be as effective as the special fluorescent bililamps, however as LEDs have a more pronounced spectral peak, it may be possible that superior combination of LEDs and phosphors may replicate a faster reacting action spectrum.

LEDs can offer similar, if not the same phototherapy as the best fluorescent bililamps, but as all lights dim in brightness as they age, control algorithms for LEDs can ensure maintained light levels are delivered for a 15 year bililight source service lives. This is not yet being done for phototherapy but I trust testing may soon start.

Both terms and their effects, need simultaneous review when discussing LED performance decline over time.

Depreciation commonly is used to refer to the decline in brightness over time as a light source is used, known as lamp lumen depreciation.

LEDs also degrade.

Degradation, many may think of chemical decomposition but there is also elegant degradation. One or both of these conditions seems commonly referred to, and one or both, may occur at the same time.

LED performance depreciates over time as less lumens are emitted. The more any light is used, the more a light source brightness dims over time.

LED lumen depreciation can be solely due to heat conditions. Research has verified this independent of LED operation.

Evidence of LED lamp lumen depreciation is useful, however we know in addition to lumen deprecation, LED Kelvin CCT (Correlated Color Temperature) changes over time.  If change in apparent colour appearance of an LED, and lumen depreciation are plotted at the same point, we can see how these changes may parallel each other in some LED sources, while for others, they may be independent.

Decline in LED lamp lumens and colour temperature change over time varies between manufacturers. It seems sensible to test LED Kelvin CCT measurements and plot them at the same time as Lumen measurements are taken when LED life performance testing is conducted.

LED lumen maintenance curves decline due to LED use and thermal conditions.

All lamp lumen performance declines due to use. Lumen maintenance curve decline is also affected by the number of times a lamp is turned on & off, the thermal environment of the lamp and luminaire, and lamp ballast/driver electronics.

New research shows LED lumen performance declines due to heat without LEDs being turned on. During testing LEDs were turned on only for short duration lumen measurement data collection.

This has large implications for exterior LED lighting where high ambient temperatures are present, as is typically found inside luminaires exposed to direct sunlight during daytimes when luminaires are not on.

The higher the ambient temperature, the faster LED lumen performance declines. Not all high brightness LEDs perform the same way.  Different manufacturer’s LEDs exhibit different rates of decline.  Variation in lumen performance decline must be due to differences in LED manufacture technique and material.

I am interested to review Electron microscopic time-elapse images & data collected at different points along the lumen maintenance curve. No doubt, there is something new to discover to improve manufacturing technique & fabrication for more robust LEDs.

LEDs Target Breast Cancer Tumours:

US Scientists have developed the first hand-held optical scanner for early detection of breast cancer. The device, is intended to complement traditional breast screening methods.

It is thought that 1 in 10 women will develop breast cancer.

A portable device both patients and doctors could use would provide women at high risk a way of regularly examining themselves.
See full article at http://physicsweb.org/articles/news/10/6/13/1

Light at Night Increases Breast Cancer Risk:

The below URL is a direct download link to a video of a current seminar reviewing current research on Light & Breast Cancer Research, from Rensselaer Polytechnic Institutes’s Lighting Research Center in New York. http://tinyurl.com/kopko

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