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LED Colour Variation
18/03/13: Phosphor-white LEDs can suffer from an intrinsic and very noticeable variation in colour and CCT as our article explains. » More
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Calibration Lamp Depreciation
11/07/12: Calibration lamps slowly depreciate - something which we take seriously. Understand the causes of lamp ageing and what you can do about it. » More
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LED Colour Difference Specifications
20/06/12: Our guide will help you to understand the metrics that are used to define the difference in colour between LEDs, such as SDCM and MacAdam ellipses. » More
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Are Halogens History?
31/05/12: Photometric Testing and the Lighting Magazine team up to see just which low voltage halogen lamps will survive the EU’s energy efficiency purge. » More
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Understanding Photometric Data Files
02/04/12: Dr Gareth John - Photometric Testing's Technical Director - separates fact from fiction explaining standard photometric data formats, .ies & .ldt files, and polar charts. » More
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Win a T-10A Lux Meter with Talking Photometry!
29/03/12: Here at Photometric Testing we are giving away the latest, high accuracy photometer, essential to any lighting specialist as part of the launch of our new publication, Talking Photometry. » More
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Napoleon Has A Lot To Answer For: The Origins of The Metric System
29/03/12: For the origins of modern commerce we must look to Napoleon Bonaparte, whose actions – in part – laid the foundations for free trade and the modern day European Union. » More
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Into the Twilight Zone - How Scotopic Lumens Boost LED Performance
05/03/12: Into the twilight zone - how the blue light peak of phosphor white LEDs boosts scotopic performance and gives free lumens under low light conditions. » More
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The Torch with the Power of a Million Candles
05/03/12: We're not complete geeks here at Photometric Testing. We do get some time off, and we recently attended a performance by Rhod Gilbert who recounts discovering a torch with the power of a million candles. A must-have, we say! » More
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Claimed versus Actual CCT
02/03/12: Testing conducted for the United States Department of Energy's CALiPER programme reveals that many LED retrofit lamp products fail to meet claimed colour quality specifications. » More
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When is a Lumen not Very Useful?
07/02/12: A high number of lumens is always good, but its where you point them that really matters. Let's talk about the concept of "useful lumens" and how it applies to directional lamps. » More
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Guide to Photobiological Safety
02/02/12: The photobiological safety of artificial optical radiation is a hot topic. Learn about BS EN 62471 and the Artificial Optical Radiation Hazard Directive in our Guide to Photobiological Safety - and avoid getting burnt. » More
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LED Specifications - Fact or Fiction?
02/02/12: Some may regard LED specifications as works of fiction. Here at Photometric Testing, we say that understanding how LED output varies with temperature will help you to seperate truth from fiction.
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The Perfect Integrating Sphere - Perfectly Impossible?
02/02/12: The perfect sphere is perfectly impossible. That's not to say that our 1m Labsphere is in any way sub-standard. However, any "integrator" that isn't spherical or doesn't use a high reflectance paint spells trouble. » More
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Watts Wrong with the Lumen?
02/02/12: "Sheer Lumenacy - EU to replace watts with continental lumens". The Daily Mail considers the change in the labelling of light bulbs which are now specified according to the light they emit rather than the electrical power they consume. » Daily Mail Article
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Understanding Goniophotometry
30/10/11: Understand how near-field goniophotometric measurements work in this white paper originally published on ElectroOptics.com
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A Guide to Colour Rendering
30/10/11: The colour rendering index (CRI), is a quantitative measure of the ability of a light source to reproduce the colours of various objects faithfully in comparison with an ideal or natural light source. Understand all about CRI and how it is measured in our Guide to Colour Rendering. » More
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A Guide to Colour Temperature
30/10/11: Even though two white LEDs may have the same CCT (correlated colour temperature) they can appear a very different colour. Understand how this is possible in our Guide to Colour Temperature. » More
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