There are numerous articles that are discussing the advantages and disadvantages of hot lights and LEDs. Knowing these, I want to share my opinion from a practical standpoint.
Although I'd like to go straight to the point, let me first outline some of their properties. My thoughts would be from the perspective of small-budget productions (both for stills and video).
They have been here for many years and have been the go-to light for many professionals mainly in the motion pictures industry. I'll talk about halogen lights and will deliberately omit HMIs. Most small productions use HMIs only as rentals, but in general, independent filmmakers use their own hot lights and that's usually the classic halogen ones.
They are relatively cheap and powerful for their price. Their color temperature is easily controllable with gels and the beam contains the full light spectrum. Their disadvantages come with their name: they become hot, draw a lot of electric current, and require a strong power source and circuits. Often they come packaged in a big body to allow passive and active cooling.
The LED technology is not that new, but its adaptation to the photography and filmmaking industry is still ongoing. There are flaws that are fixed on the go, but more often we see them used in big productions.
They are light, small, draw less power than hot lights, can be run on batteries on location. On the other hand they are more expensive and less powerful when compared as Watts for a dollar.
There are a numerous number of issues with LEDs when it comes to their color. That's one of the reasons for their higher price. Manufacturers who have dealt with the incomplete color spectrum have a significantly higher price tag on their products. There has been a recent article where representatives of two of the major LED lights manufacturers discussed the reasons why RGB LEDs' can lead to major and unexpected color shifts. This is why if LEDs are utilized on color-critical jobs, it is better to use color gels over daylight-balanced LEDs rather than dialing the RGB color in. The latter has been one of the major advantages of RGB LEDs. They are supposed to eliminate the need of color gels and this way save light output power. Fortunately or unfortunately, gels are here to stay.
Why Hot Lights?
This is based on my practical experience and the projects that I usually work on. I shoot corporate videos, music videos, and short films. All that happens on location. When I am in interiors I like to use multiple lights to shape the scene and my subjects. When I am outside I use diffusers and reflectors to add or subtract light. If I want to fight the sun I will need something very powerful and in most cases LEDs are not an option. I'd rather use an HMI source or more powerful halogen hot lights.
One of the main differences between professionals and non-professionals is that professionals invest in gear thinking about the return of their investment. Non-professionals usually buy lights, because they like them, and because their income does not depend on using that gear. In my case I have to be aware of the ways to return my investment and that's why my calculation is biased.
For a corporate video I light the subject with two or three lights and eventually put one or two to light the interior. If there's a bright sun from windows on the back I have to have a key light that is strong enough to balance the room ambience. Balancing the color temperature happens by putting a blue gel to make it close to 5200K which cuts about a half stop. Then I may want to soften the harsh light with a scrim or a softbox which takes another stop. In this fashion a 1 kW light will result into about a 350 Watt source. I can get a 500 Watt output if I decide to keep the light without a blue gel which looks nice in a corporate video, naturally creating color contrast between the foreground and the background. The other light sources I utilize are also in the 800-1,000 Watt range. This makes about five lights as per usual.
For music videos shot in interiors I need at least five or six powerful lights. The same for short films where there may be demand for even more power.
As a summary I need at least six lights to be able to execute most of these tasks. I can get 800 to 2,000 Watt hot lights for about $180-300 each. I can always purchase cheap Red Heads If I need more lights. This means that my total investment in hot lights would be less than $2,000.
If I decide to work with powerful LEDs, I have to spend not less than $700-800 per unit. This investment will be more than $3,500.
At the end of the day the client wants a nice looking image. They don't care if hot lights or LEDs are used. The power consumption of hot lights in the 1K range is not that immense and unbearable for most electrical installations, especially if you distribute them in different circuits.
When buying gear we should also think about servicing it. When it comes to hot lights they are very simple, because most of the time it's just a metal body and a halogen light bulb on the inside. You have to have a few spare light bulbs at hand and that's pretty much it.
When Should You Use LEDs?
LEDs are very useful when you have to put them in spaces where you can't place an object that emits a lot of heat, which can be hazardous to the scene, the actors, the models, and the crew. I find that for now small LEDs are the best investment in small lights for my kind of work.
I am sure that a fellow filmmaker will be able to write the same article for LEDs stating sound arguments favoring LEDs to hot lights. But, as I said, the point of view of the article is based on the ROI value in the scope of the work and budgets I am working into. I think I'm going to invest into more powerful LEDs when their power-to-dollar ratio comes closer to that of the hot lights.
What is your opinion on the matter? Would you invest in LEDs if you were in the same situation?