Author Topic: FUN301 - Lighting  (Read 3460 times)

Pa Kalsha

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FUN301 - Lighting
« on: December 11, 2016, 10:02:37 AM »
Lights
Once you’ve got your workspace just the way you like it, it’s time to make sure you can see what you’re doing. The best light for a studio is natural light coming from a stable source, such as a window facing towards the nearest pole, north or south depending on which side of the equator you live, but we can’t all be that lucky. The rest of us (plus those lucky few, if they want to work after dark) have to consider the way we light our workspace and engineer it to our best advantage.
To start with, you’ll need a good desk lamp - ideally something that can be angled and repositioned - and an overhead light. The important part is the bulbs themselves, specifically their colour temperature, brightness and colour rendering index.
  • Colour rendering index (CRI) is the ability of a light to accurately display colours.
  • Colour temperature is measured in Kelvins or K, and relates to the colour of the light itself.
  • Brightness is measured in lumens. For an overhead light, aim for a total of around 1100 lumens. For a desk lamp, go for 450-800 lumens.
Colour rendering index
The most important factor in selecting a light source is its colour rendering index; which is a rating out of 100 given to its ability to show colours accurately compared to a reference source. Lower CRI values will distort colours and the results won’t be what you expect when you scan the picture or look at it in daylight.
Where the bulb manufacturer gives the CRI (it might be called “colour accuracy”), and you’ll want to look for anything over 80. Unfortunately, this rating isn’t always listed on the box, but the phrase “full spectrum” is usually a good indicator.
Since CRI is measured against lights of the same colour, even a CRI of 95 won’t help you much if the light has a colour temperature under 5000k.

Colour temperature
Colour temperature (or, colour corrected temperature) describes the dominant colour tone, from warm to cool (red/yellow to blue) using the Kelvin scale:


Lamps with a colour temperature below 3500-4000 K are considered to be “warm” (yellow) light sources, and those with a temperature of less than that are “cool” (blue). Daylight bulbs have a colour temperature of at least 5000 K, and are also called “cold” lights because of the blue light they emit.


Brightness
The light emitted by a bulb is measured in lumens. Old-style incandescent bulbs were rated in Watts, but was misleading - their Wattage showed how much power they consumed, not how much light they produced -  and new bulbs are significantly more energy efficient, so manufacturers have changed to giving the lumen value instead.

If, like me, you’re old enough that you still think in terms of Wattage but don’t know how that relates to lumens, look for a number of lumens about ten times that of the wattage you’re after.

WattsLumens
25180
40360
60600
1001100
1501400

The amount of light you need to light a room depends on environmental factors - the size of the room, the placements of the lights, and so on - but the general recommendation is 800-1000 lumens to light a ‘task’ area (such as a desk). Between a 600 lumen overhead lamp and a 250-300 lumen task lamp, you’ll be well-covered.


Image credits
https://commons.wikimedia.org/wiki/File:Incand-3500-5500-color-temp-comparison.png
« Last Edit: December 11, 2016, 10:04:43 AM by Pa Kalsha »