Alex Forsey Photography

HMIs and continuous lighting

Continuous light is a wonderful but expensive medium to use. You have the freedom to see what you're getting as you place your lights. If you have a lot of experience with flash you will appreciate this. The down side is that, unlike our friends the film makers, if we want to freeze movement we need more output from our lights and this gets more expensive as we increase the size and power. This is why flash has become so popular.

If you have the budget and the muscles these are beautiful lights to work with. They can also be mixed nicely with flash. Although if you are working with a moving subject you will have to bare in mind that you will get shutter blur if your shutter speed is not adequate and your continuous light source is brighter than your flash.

HMIs put out four times as much light as a tungsten light of the same wattage. The price you pay for this advantage is considerable and they come with ballast.

HMIs are daylight balanced and can be mixed freely with flash without concern for colour balance. Although, by this I don't mean you shouldn't think about it. The colour of light is always a concern in terms of what you are trying to create. Even with black and white the colour of light needs to be considered, as the tones in an image will change with the colour of the light.

The colour of the light from these can be a little blue when they are brand new and they warm up with age.

For this image I used daylight and filled with a tungsten head. For a fill light to be successful it should be barely noticeable. Unless this is an intentional effect to give your image a surreal feel. It isn't always necessary to have a fill light when shooting film if you are happy for areas to got to total black. As with film noir sometimes what makes the image interesting is what you don't see rather than what you do.

With digital I think this could be a little trickier. So far, many digital operators have told me the way forward is to add some light to the shadows and then remove this in retouching and increase the contrast post shooting. I find this a little dull and for me takes away some of the magic of seeing what you're getting in front off you. Which for me is the pleasure of shooting with continuous light.

If you want to master continuous light I would recommend studying the work of the masters. Cinematographers like; Lance Acord, Darius Khonji, John Alonzo and Michael Chapman. These guys are magicians who understand light and how it affects an image and how we perceive it.

HMI FRESNELS

These are the standard HMIs you will come across. They are very versatile and make good fill light when bounced or put through diffusion. The higher output ones make very nice key lights. These have a lens with circular ridges that reflect and refract the rays of light to give a cleaner shadow.

HMI PARs

Standard HMIs have a soft light quality that softens with size. If I were trying to recreate full summer sun I would use HMI PARs. These are a much punchier light source and have a longer throw. They come with lenses that slot into the front.

The lenses usually available are; super wide flood, wide flood, medium flood, narrow spot, and very narrow spot. Be careful when ordering HMI PARs as I have had lighting companies and production teams give me standard HMI's not being aware that there are different types. This is rare but I now make a habit of checking that people understand and are aware of exactly what I'm asking for.

They come as 200W, 400W, 800W, 575W, 1200W, and 2.5K without special power needs. Then 4K, 6K, 12K and 18K which will require a generator unless you have access to 3 phase power.

HMI PARs get incredibly hot. I recommend the use of heat proof gloves when handling these lights.

Gels

Most HMIs produce a daylight matching light of between 5,600°K-6,000°K. I find this colour temperature a little blue most of the time and tend to warm up the light with some straw colour gel or CTO (Colour Temperature Orange). Gels are the best way to control the mood of your light. The colour of the light ultimately tells our brains what time of day it is and this is one of the best tools at our disposal.

The standard gels used for correcting colour are the CTOs (Colour Temperature Orange) and CTBs (Colour Temperature Blue). These usually come in 1/4, 1/2, and full stops. Depending on how much correction you want.

Update on Thursday, July 2, 2009 at 12:19PM by Alex Forsey Photography

Kino Flo's

Kino Flos are a beautiful and soft light source. They look like fluorescent tubes but they are daylight balanced. These come in many shapes and sizes and are commonly used on feature films. The most commonly used in stills will be the 2 bank, 4 bank, and 10 bank standard size. Best used with high ISOs as they don't give out much light.

As an example I was using two 10 bank lights either side of my model at about 3-4 ft away and I was getting about F5.6 at 60th sec on 400 ISO film. Not great if you want to do movement shots and freeze them but none the less a beautiful light source that has its uses.