Everything the Artist Needs to Know About Lighting in the Studio or Gallery - Types of Lighting (Part 3 of 5)

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The type of lamp or bulb you choose has a significant bearing on the quantity and quality of light you can obtain.  A range of options are available to improve existing lighting.  Desk lamps are cheap enough that you can have several types of lighting available, and avoid the need for an electrician to wire in fixed fittings.

For the average artist, a good lighting arrangement can be easily achieved.  An adjustable desk, clamp, or floor standing lamp fixture which can direct light onto your work is a cheap investment (if you shop around).  Fitting these with a 100Watt daylight corrected incandescent bulb means you’ll have accurate colour rendition for proofing, and a colour temperature similar to around 2 hours before midday.

The same arrangement can be used for lighting your subject matter (if it is small), though for lighting larger subjects you’ll need to ideally invest in photographic lighting systems.  These systems are beyond the scope of this article, though well covered in many photographic websites.

Like me, it is anticipated that the average reader of this article will wander down to the nearest lighting shop for cheaper alternatives.  Unfortunately not all bulbs are created equal, and neither is the knowledge of most employees.  Accordingly I hope to give you a guide to what you should and should not use, (or so you can outshine one of those assistants who claim to know everything but actually know very little).

 

Best cheap upgrades to existing lighting in a studio or gallery:

 

-         replace incandescent (old style) bulbs with daylight corrected incandescents;

-         replace compact fluorescents (energy savers) with daylight corrected incandescents if colour reproduction is important;

-         replace old fluorescent tubes with newer triphosphor tubes with an 8xx or 9xx rating (see below);

-         buy a desk/floor/clamp light for directing onto your work and install a daylight corrected incandescent.

-         Replace incandescent reflector bulbs in spotlights with xenon-halogen bulbs (where UV is a problem either use xenon, or a halogen bulb with a built in UV filter);

-         Believe what’s written on the box, over what the salesperson says.

 

 

Lighting Types & Characteristics

 

Daylight incandescent       

   Lighting your work

   Lighting subject

   General area lighting

Pros/Cons                           

   Cheap, very good colour rendition

   Good colour temperature

 

Normal incandescent

   Lighting your work 

   Lighting subject                  

   General area lighting

Pros/Cons                           

   Cheap, very good colour rendition

   but poor colour temperature

 

Halogen

   Lighting your work 

   Lighting subject                  

   General area lighting

Pros/Cons                           

   Cheap, excellent colour rendition

   but low colour temperature

                                            

Xenon-Halogen

   Lighting your work 

   Lighting subject                  

   General area lighting

Pros/Cons                           

   Cheap, excellent colour rendition

   but low colour temperature

 

Compact Fluorescents (energy savers)

   General area lighting

Pros/Cons                           

   Cheap to buy and run

   Poor colour rendition except

      full spectrum models

   range of colour temperature

 

Fluorescent tubes

   General area lighting

   Lighting subject

Pros/Cons                           

   Relatively Cheap if you have fittings

   use 8 or 9 series models (see below)

   choice of colour temperatures

   older unrated tubes should be upgraded

      (unrated - i.e. no 8xx or 9xx specification on tube)

 

Xenon Flood/discharge

   Lighting subject

Pros/Cons                           

   expensive specialist product

   Excellent colour temp & rendition

   often used for photographic work

   use where good lighting critical

 

There are two main types of lighting in a studio – work (task) lighting and general area lighting.  If you are fortunate you will have both, and should try and reach this ideal as soon as possible.   General area lighting stops you bumping into things, and being able to find where you put your paint brush.   Colour reproduction may be not so important, but upgrading your bulbs to give better colour reproduction is a good investment – often you will want to inspect things other than on your working area.

Task lighting is localised and should be able to be directed onto your work area, as well as any proofing and review area.  You will need to decide what suits your work habits – localised lighting may be as simple as buying a desk lamp or clamp light fitted with the appropriate bulb/lamp. 

Fluorescent tubes provide good even lighting over a large area.  Some tubes give very good colour reproduction – providing you know what you are looking for.  Upgrading existing fluorescent tubes can be a cheap upgrade for even lighting, at a colour temperature of your choice, and with good colour rendition (reproduction).

 

luorescent tubes use phosphors (the white stuff on the inside of the tube) to produce light.  Fluorescent phosphors (less so at the budget end) are often formulated to give good colour reproduction – this is due to demands in retail.  Most good quality daylight or warm tubes will give a full spectrum light allowing for good colour reproduction.

So which tubes do you need?  Ideally you will want to specify 835, 840, 930 or 965 fluorescent tubes.  The last two digits represent the colour temperature in Kelvin (e.g. 35 means 3500K) which gives you a great choice of colour temperature. 

The first number represents the accuracy of colour reproduction/rendition (and in some ways reflects the colour spectrum of the light source – see earlier article).  An 8 series tube gives very good colour reproduction, while a 9 series tube gives excellent colour reproduction (and is typically used in photographic light boxes).  10 is the theoretical maximum under the current scale and currently is only achieved by full spectrum filament lamps such as the traditional incandescent lamp, and many low voltage halogen and xenon lamps (though colour temperature can be a limitation).  The scale for color rendition is the Ra – hence a 9 series tube has an Ra in the 90s, an 8 series tube has an Ra in the 80s.  Incandescent lamps typically have an Ra of 100, as does sunlight.  The higher the number the better. 

At the lower end of the budget, a standard fluorescent tube fitting with 840 tubes (these are the most common tubes available which have a rating) is adequate for general area lighting in most art studios.  If there is no rating on the tube, don't buy it. 

Compact Fluorescent Lamps (CFLs or Energy Savers) do not normally publish information about the spectrum, and sometimes not about the colour temperature (other than ‘warm’ or ‘cool white’).  As these are made by a variety of manufacturers, whose choice of phosphor (and hence colour spectrum) may be dictated by phosphor cost, or brightness per watt, CFLs are not generally recommended for when accurate colour rendition is important or colour temperature is critical.  The exception is the relatively uncommon full spectrum CFLs.  As a general rule CFLs are good for energy efficient general lighting when you don’t have the choice of fluorescent tubes, but daylight corrected incandescents will give better colour rendition and should be used in more critical areas of your studio.

Low voltage halogen (and xenon) bulbs can make good work lighting and most low voltage types are full spectrum, but do not provide for much choice in color temperature values – you are typically limited to around 3000-3500K though Vivalite produces a 5000K low voltage halogen lamp.  For work which will be exhibited under this type of lighting, having these bulbs present in the studio can be useful.  Desk and clamp lights which accept halogen bulbs are cheap and readily available.

Mains voltage halogen lights appear to be less bright, and less energy efficient than low voltage equivalents, but the newer mains xenon-halogen replacements appear to address many of these limitations.  Currently, low voltage halogen lamps are still preferable.  If you are fitting new lights, you are probably better to choose fluoresent tubes, or low voltage halogen fittings with xenon-halogen bulbs.

Incandescent lights, despite their obvious colour cast, actually produce a very good spectrum of light.  The better solution is to use a Daylight Corrected Incandescent Bulb,  which is made by a number of manufacturers.  It looks like a clear incandescent bulb with a clear blue coating on the glass to remove excess red-orange from the emitted light spectrum and thus increase the colour temperature.  I have one of these in a desk lamp and have found it to be about the best (cheap) solution for reviewing and proofing work (as well as for working under).  The bulb I bought today cost under NZ$7, and was available in both bayonet and Edison Screw fittings.  The problem with incandescent bulbs is poor lifetime and poor energy efficiency.  However, if good colour reproduction is required and existing fittings take this type of bulb, then you are probably best to buy and install the daylight corrected incandescent bulbs.

LED lamps.  Probably best to stay away from these currently – at the moment there is very little data about the spectrum and colour temperatures of this form of lighting.  They also come from a wide variety of sources, with different levels of quality control.  Unlike single colour LEDs, most white LEDs actually use an internal internal UV LED to excite a white phosphor.  Here we run into the same problem as most non-‘full spectrum’ Compact Fluorescent Lamps – one is never quite sure about the spectrum of the light from the phosphors chosen.  However this is likely to change as LEDs become more popular as a mainstream light source, and it is increasingly used in specialised areas such as museums and galleries.  If you find an LED lamp with specifications indicating it is full spectrum, then by all means consider it, though low voltageLED lamps often require special control gear (and many cannot be directly substituted for a low voltage halogen lamp unless a wire wound transformer has been used)

What do I have in my studios?  I have several downlights with higher end compact fluorescent bulbs for general area lighting.  Over my drawing desk I have halogen ceiling downlights fitted with low voltage xenon-halogen bulbs, which are brighter than halogens and produce minimal UV light - you are likely to see these being more common place in galleries until LED lamps take over.  I also have, on my drawing desks, desk lamps with Daylight Corrected Incandescent Bulbs for working, proofing, and reviewing.

If you can, it is best to have a variety of light sources to emulate the conditions under which your work will be reviewed.  Also, there is no perfect substitute for the sun, whose light characteristics also change during the course of a day and due to atmospheric conditions.  Having a range of lighting can help you simulate different effects, and allow for reasonably accurate colour rendition under different colour temperature conditions.

Examples of detailed lamp data sheets:

Mains halogen http://www.lampspecialists.co.nz/productPDFs/5255h.pdf

CFL energy savers http://www.lampspecialists.co.nz/productPDFs/5224h.pdf

Low voltage halogen http://www.lampspecialists.co.nz/productPDFs/5257h.pdf

Fluorescent tube http://www.lightaudit.com/data/phillipsfluorescent/master_tel5_high_efficiency.pdf

MR16 low voltage halogen http://www.prismaecat.lighting.philips.com/ecat/Light/ApplicationRouter.aspx?fh_secondid=924057417101_2&fh_reftheme=en_NZ_en_HK_promo_75140920%2cseeall%2c%2f%2fprof%2fen_NZ%2fcategories%3c%7bfapplg%7d%2fcountries%3e%7ben_NZ%7d%2fstatus%3e%7bact%7d%2fcategories%3c%7bc_0002fapplg_2246_ap01%7d%2fcategories%3c%7bc_0022fapplg_2249_ap01lhal%7d%2fcategories%3c%7bc_0002fapplg_2264_ap01ldir%7d&fh_location=%2f%2fprof%2fen_NZ%2fcategories%3c%7bfapplg%7d%2fcountries%3e%7ben_NZ%7d%2fstatus%3e%7bact%7d%2fcategories%3c%7bc_0002fapplg_2246_ap01%7d%2fcategories%3c%7bc_0022fapplg_2249_ap01lhal%7d%2fcategories%3c%7bc_0002fapplg_2264_ap01ldir%7d%2fcategories%3c%7bf_0022fapplg_2264_pal_hbrilalu%7d&fh_eds=%c3%9f&fh_refview=lister&tab=&family=&&left_nav=nz_en&

 

article image - www.hughmitton.com

 

Everything the Artist Needs to Know About Lighting in the Studio - Colour Spectrum (Part 2 of 5)

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Colour temperature is important in determining how a work will appear at different times of day, or in different lights.  However accurate colour reproduction under artificial light is equally affected by the colour spectrum of the light produced.

 The colour spectrum of a light source has a significant effect on how accurately colours are reproduced.  Look at a rainbow, created by the sun, and you will see the colours spread uniformly from red to violet.  However, if we split the light from some artificial light sources into their spectrum (e.g. through a prism), there may be gaps in the spectrum produced.  These gaps will have a significant bearing on colour reproduction – if there is a gap in the yellow region, then yellows will not be reproduced well  when viewing under that light, while colours which reflect yellow light (e.g. orange) will be out of balance with other colours.  The consequence is poor colour rendition, as different colours in your artwork will be out of balance with each other.

 This is a different problem to colour casts such as from low colour temperature light sources.  Here, most of the colours will be balanced in intensity when the art work is viewed, but colours towards the red-orange end of the spectrum may be enhanced in comparison to bright noon daylight.  This is entirely different to when a light source’s spectrum causes greens to appear as black, for instance, but reds, oranges, blues and violets reproduced faithfully.  Therein lies the difference between colour temperature and colour spectrum issues.

A good (extreme) example of gaps in the spectrum are the orange sodium vapour lamps often seen in street lighting – highly efficient, but with significant gaps in the visible light spectrum.

Some compact fluorescents can suffer from incomplete spectrum problems, as some focus more on achieving a particular brightness and colour temperature than colour reproduction.  There is no easy way to know which compact fluorescents (sometimes known as energy saver lamps) are better or worse, though some are marketed as “full spectrum” lamps.  In this case the phosphors (the white stuff coating the inside of the tube) are chosen on the basis of achieving a full and complete colour spectrum.  Fluorescent tubes (that’s the long tubes as opposed to the moden compact types with a bayonet or Edison screw fitting) do not always suffer this problem as they have long been used in applications requiring good colour reproduction, and have had significant time spent on improving phosphors - see the next article entitled ‘Types of lighting’.

 As well as gaps in the colour spectrum of a light source, there may also be uneven weighting of colours within the spectrum with certain lighting sources.  Photographers know that many older type fluorescents (using old (non-modern) phosphors), and mercury vapour lamps,  produce a strong green cast as well as having incomplete or un-natural spectrums . In contrast the old incandescent lamps produce a full spectrum but more light in the orange-yellow range than the blue violet (unless you buy a daylight corrected incandescent – see below).  Most modern low voltage halogen and xenon lamps also provide a full spectrum coverage, and are also good for accurate colour recondition.  The only problem with these non-fluorescent options is limited choice of colour temperature, which is problematic if you wish to simulate sunlight/daylight at mid-day. 

In summary colour spectrum affects the accuracy of colour reproduction (as we see things under the light source), and is an important consideration when choosing lighting.  However, colour temperature is equally important for determining how a piece of artwork will appear in daylight, or under actual lighting conditions after installation.  Very much you need to consider both colour temperature and spectrum if you intend to work or review artwork under artificial light.

Interesting Links

full spectrum energy savers- http://www.viva-lite.co.nz/

Daylight corrected incandescent bulbs - http://www.lampspecialists.co.nz/productPDFs/5041h.pdf

Fluorescent tube data http://www.lightaudit.com/data/phillipsfluorescent/master_tel5_high_efficiency.pdf

 

 

Everything the Artist Needs to Know About Lighting in the Studio - Colour Temperature (Part 1 of 5)

Sun

In this series we look at artificial lighting in the artist’s studio. In the first article we talk about the colour temperature of  lighting.  Colour temperature is important as it reflects the colour cast that a light source projects onto a work.  This affects colour reproduction, but can also enhance or detract from a work.

                 

Last week I had some artist friends around to celebrate my birthday.  When we get together the topics wander, but one of the print makers asked about lighting for reviewing their prints as the days get shorter and gloomier.  Fortunately I was able to show them a day-light corrected incandescent bulb I had bought the day before.

 

As the discussion progressed, I realised that many artists, while knowledgeable in their respective fields, have a limited knowledge of lighting – as my introduction to art was via photography I had assumed that everyone had the detailed knowledge of lighting I possessed.  Not so.  Accordingly I have decided to share the following information in a series of posts – “Everything the Artist Needs to Know about Lighting – and some more besides”

                       

 

There are five main considerations regarding lighting affecting the typical artist in their studio.  These are:

i)                    colour temperature

ii)                   colour spectrum

iii)                 type of lighting

iv)                 position of lighting

v)                  brightness of lighting

 

Colour Temperature

 

Most artists will realise that sunlight close to sunset (or sunrise) is quite yellow or orange in colour.  In contrast, midday sunlight on a cloudless winter day is a bluish white.  Landscape artists will be aware of these changes and how it strongly affects the visual qualities of the landscape.  However, not all will be aware of the technical side of colour temperature, and how it relates to artificial light.

 

The normal scale for indicating the colour of lighting is “Kelvin” (which is also a unit of temperature).  The symbol for degrees Kelvin is “K”.  Essentially the colour of lighting (in Kelvin) represents the colour of light emitted when heating a block of carbon to that temperature.  Fortunately, people have created tables which give an easier indication which most artists can relate to:

 

1900K                         typical light emitted by a candle flame

2200K                         typical light at sunrise or sunset

2600-2900K                typical light by common incandescent bulb

3000K                         typical light by standard halogen bulb

4000-5000K                typical sunlight 2 hours before or after midday

5500-6500K                typical noon sunlight (winter sunlight can be much higher)

5500K                         typical camera flash

7500K                         outdoor shade areas on bright day

7500-10000K              cloudy day

10000-12000K            bright clear winter day with blue cloudless sky

 

It should be noted that Kelvin is not a measure of brightness, but colour temperature (and hence gives an indication of colour cast – the lower the number the more yellow-orange-red the light, while the higher the number the more bluish-white the temperature).

 

For the artist, colour temperature is important as it will alter the colour reproduction of what you are looking at.  Accordingly, it is useful to review or create your work in a colour temperature similar to that in which the work will be viewed, and for this multiple light sources may be desirable to emulate different situations. 

 

For reviewing and proofing work, colour temperature is not the only consideration with regards to accuracy of colour reproduction – something we shall discuss in the next article of this series.

Most artificial lighting will specify a colour temperature on the package, though most standard incandescent bulbs will fall within the range above (incandescent bulbs don’t generally state colour temperature on packaging.  Personally I like to work in a colour temperature range of around 2800 to 3500K.  However for proofing I will use a daylight corrected incandescent bulb – unfortunately most manufacturers don’t specify the colour temperature, but research suggests they are typically around 3800K.

 

Remember also that a light source near a strongly coloured wall will affect the colour temperature of light in the studio.  Light bouncing off a white wall will be quite different to that bouncing off a red wall.  Hence consider the positioning of your light sources in relation to coloured areas of the studio, as well as the colour temperature of the light source itself.

 

Also the artist should be aware of the effect of colour temperature when photographing works – not everyone is able to afford or access the services of a professional photographic setup for fine art reproduction.  Also, the sun and weather are not always co-operative when you want to pop outside to photograph your latest work so you can email it to a gallery.  Colour temperature has a strong effect on film media (with few exceptions, you need to buy a film specific to your lighting conditions).  The effect is just as pronounced with digital photography, though most modern digital cameras have an automatic colour balance (which can be manually over-ridden).  The problem is that the colours of your artwork can upset automatic colour balance, and you may be forced to manually select a colour balance setting which matches the colour temperature of your lighting.  We will look at this more fully in a following series about “Photographing and Reproducing Artwork for the Average DIY Artist”

 

More reading on Colour Temperature - http://www.ephotozine.com/article/Guide-to-colour-temperature-4804

article image courtesy of NASA