Friday, October 16, 2009

Food Photography: Continuos Lights

Do you have time to take pictures only late in the evening? Is the room where you shoot dimly lighted by small windows?
This post continues the analysis of the basics of food photography describing the more (theorically) "simple" systems of photographic lighting: the continuos light ones.

It is called continuous light because lighting is produced by lamps, enabling you to see their effect in real time as it resembles the behavior of natural light. For that reason it is sometimes preferred to flash lighting whose effects on the scene are not always easy to be "predicted".

The continuous light is the lighting system used in movie sets and television studios and in all those occasions where it is necessary to reproduce motion scenes and therefore, for obvious reasons, you can not use flash lights.

Given those benefits you'll wonder why these devices aren't always used: as I'll list the various kinds of continuous light on the market you will understand that, as in all things, there are drawbacks and compromises to which the user must submit.

Hot Lights

They are the most "ancient" continuous light devices as they are in practice nothing diffirent than iridescent bulbs (tungsten bulbs as in the old lamps you always used at home) or, more recently, quartz (also called halogens).
The advantage of low cost (you can also use some equipment not specific to photography) is however balanced by three major drawbacks: the first is that they are hot. DAMN HOT. Especially in relation to the power of light emitted.
That is in fact the second problem.
Since they are energy-inefficient, to illuminate a scene so you can use slower shutter speeds and low ISO sensitivity you'd need hot lights from 2-3000 watts up.
They are therefore not the best choice if you have to shoot people in small rooms unless you want to experience what the food could feel in the oven.
Instead for shooting food, which is usually pretty "static", you can use less power, from 500 to 1000 watts.



Apart the heat problems (forget to shoot parfaits, ice cream, etc. with hot lights) if you need to "modify" the light (to make it softer, thereby targeting, etc.) you'd need to use specific photographical accessories that must withstand high temperatures, whose high cost erases in part (if not entirely) the economical advantage of which I formerly spoke.
Above all you must really be careful with certain materials like paper, and other highly flammable, because the risks they take fire if too close to the lights are real (I tell you from personal experience).
The third problem with this type of light is the "color" they produce which is "red" and "hot" and must be balanced at shooting time or, in a worse way, in post production (as I described in this post).

Cold Lights (Fluorescent Lights)

Fluorescent lights have had a significant technological improvement recently. Just few years ago there were little differences between them and the usual office "neon" lights. They have good energy efficiency, with the same watt power they emit a lot more light than hot lights. They also have the considerable advantage of being considerably less hot, for this reason they soon came to be part of photography and video equipment. Take also in count that the color of he light emitted, which in old fluorescent lights was one of the most difficult to control because of its unpredictable greenish tint, with modern light daylight lamps is considerably closer to the sunlight (the famous 5500 degrees Kelvin, do you remember it?).



Which are the disadvantages then? The biggest is that fluorescent lights are more "cumbersome", for the same power, than hot lights, not to talk about flash lights. Another problem is that both the power than the "daylight" term are used in in a very "optimistic" way by the light makers.
The ratio of 1 to 5 with hot lights (ie a 20 watt fluorescent bulb should do the same light as a 100 watt tungsten) is quite debatable indeed, by personal practical experience is actually more closer to 1 to 4, while "daylight" lamps produce a light with a color of about 4000-4500 degrees Kelvin, thus necessitating a white balance correction anyway.
Despite these limitations, that prevent fluorescent light systems to have the whole range of accessories available to flash systems, they remains a good choice especially for those, like us, need to take pictures of static subjects such as food and therefore do not need of high power lighting.
Personally I also prefer because them because light emitted in a continuous way makes easier to shoot photos that looks like they were taken with natural light, which is still the best way to make food look appetizing.

HMI lights (Hydrargyrum Medium-arc Iodide)

They are similar to fluorescent lights but they allow to build systems of much higher power, that are therefore the most used in the movie industry.



If you do not really have a lot of money and need to light a REALLY huge photo set do not even think about them, they are also very bulky and heavy as they use ballasts to adjust the voltage.

The next post I will write about the various accessories that "modify" the light and then I will continue describing the flash light systems that are the most "complete" for those who want to do studio photography.

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6 commenti :

eli said...

Io uso un foglio di carta da forno, non si incendia, ma non è il massimo e poi ho dei "farettacci" da giardino che adopero di solito per illuminare la scena quando faccio teatro.
Non dispongo di molti mezzi per cui "evviva l'arte dell'arrangiarsi".

Grazie per le informazioni sempre molto gradite:)))

Alessandro Guerani said...

Non si incendia ma diventa bello brulée (fatto anche quello con dei fari alogeni da 500w). Certo che all'inizio per capire la luce va bene anche quello, però ultimamente il costo di sistemi decenti si è così abbassato che non so se ne vale così tanto la pena.

dada said...

Certo che mi è piaciuto il post ;-) Soprattutto gli svantaggi al punto che nessuno mi ha convinto veramente (salvo, immagino, investire parecchio ;-).Anche se forse i neon sono "usabili" visto che sono migliorati. Anche da me, ancora l'arte di arrangiarsi a volte con una luce alogena ma insomma.
Grazie come sempre per le informazioni chiarissime con un pizzico d'ironia che non guasta. Buon fine settimana

Angie said...

Thank goodness you posted this today. I went today, after being fed up with trying to photograph leftovers the next day, and waiting patiently for the sun to come out. It actually rains in Orlando Florida more than Seattle Washington, or so I have been told. So I got a huge cardboard box, and cut hugs holes in the sides and top , and draped a big white sheet over it to make a make shift light box. I bought some shop lights with clamps that i can easily adjust, and put fluorescent daylight bulbs in there. I have been trying test shots in there, what should my light meter be approximately reading for proper light, don't know if I should add 2 more lights or not, I put 2 75 watts on it. If this was a crazy idea, and there is a better way, let me know.

Alessandro Guerani said...

@Angie

If you're shooting something still there's almost never not enough light. I shot with candle lights only! Main problems is to achieve what you preview in your head and use of course a tripod for long shutter times.

Angie said...

thanks! my first submission to tastespotting with the homemade lights was a success. Also the tip about white balance helped me alot with photoshop Raw. I've been sort of just playing with the image till it looks right. I need alot of practice, its so great you have this blog so I can learn from you. You are so talented!

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