HMIs: buyer’s guide (used and new)

HMIs are very bright daylight balanced lights that are very efficient. In comparison to tungsten lights they provide about x3 as much brightness per watt consumed. Moreover you don’t have to gel the light to match with daylight which makes HMIs so much more attractive over thungsten lights sources.

The lighting unit is made-up of head, feeder cable (often called header cable) and ballast. Sometimes, in case of PAR lights, you also have lenses that help you modify the light pattern (and protect people from UV radiation).

 

When buying a light a number of factors need to be considered:
Bulbs
There are 3 kinds of bulbs. Sealed PAR64. Then Single Ended and Double Ended bulbs. Older lights accept PAR64 bulbs while newer lights accept either SE or DE bulbs. PAR64 goes for about $300/bulb while SE and DE bulbs go for about $130-160. Which obviously means that older lights might apear cheap at first but their cost will start adding up as the bulb is 2x as expensive. Many PAR64 lights can be converted to SE fixtures for about $400-500.

Ballast
There are magnetic ballasts and electronic ballast. More modern electronic ballasts have something called PFC (Power Factor Correction) which makes them more efficient and even better for use with generators.

Magnetic ballasts are “simple” but heavy (about 50-60lb for 1.2k ballast) moreover when they get old they start producing hum so it’s imperative to test out the ballast before purchasing (or ask right questions) as purchasing a used replacement ballast can cost you $300-500. That said many gaffers like mag ballasts as by being such ”simple” devices they work pretty much all the time.

Electronic ballast come in 2 versions. With fan or without (to cool down the electronics inside). The fan can get quite loud! If the ballast doesn’t have “silent” mode but just “24fps” mode it potentially means that you will always have to deal with the noise of the fan.

Connectors
You will find at least a few different connectors that allow connecting the head to the ballast. If you buy a package then it’s not a big deal as one assumes that all parts work with each other but when you buy replacement you need to know the connectors you are using, moreover if you are looking to build a package it’s a smart idea to stick with one type of connectors so that the cables and ballast stay interchangeable.

 

So in essence you should be asking potential seller following questions:
Is ballast mag or electronic? If mag then is it quiet? If electronic doe sit have “Silent” mode (again is it quite)?

Is the head PAR64, SE or DE?

Is the tread near the yolk worn out?

What connectors connect head to the ballast?

 

Brands of HMI lights (with is pluses and minuses):
Arri (125, 200, 400, 575, 1.2, 1.8)
+ Popular brand. 1.8 is the brightest light one can power-up with wall outlet.
– Large heads thus not so portable. Everything above 400 require junior receiver so you can’t mount the light on basic stands easily.

LTM (200, 575, 1.2)
+ Comparably small heads. Baby pin fits on all stands.

Desisti (200, 575, 1.2)
+ relatively inexpensive when bough used (probably because of their size those lights do net get much love)
– heads are HUGE

K5600 (200, 400, 800)
+ smales heads available
– new lights cost a small fortune, properitary bulbs cost fortune (about 2x as much as other lights of similar wattage)

Other brands I haven’t used:
Mole, Sunray, CMC, Strand, CoolLights, Kobolt