Last month we looked at the basics of flash gear selection, establishing that there are three basic categories:

• Mono-lights or mono-blocs: self contained lamp heads with built in controls
• Symmetric packs which contain all the controls and capacitors: require separate plug in lamp-head: one control adjusts power over all the heads
• Asymmetric packs which contain all the controls and capacitors: require separate plug in lamp-head: one control per head adjusts power over each head

This month, I thought we would look at how the selection of such gear affects your shooting workflow.

Mono Lights

Because Mono lights each have their own control panel, you can adjust each individually. Power can be increased or decreased by dialling down the output or by moving the mono closer or further away from the subject.

Monos give you a lot of freedom to position your lights exactly where you want without long cables snaking from your pack to your head as with packs and heads; however the big disadvantage is that you have to physically get to the head to make that adjustment. Hence the ladder in the studio shots in this article.

Of course many manufacturers sell a range of monos which offer wired or wireless remote control (just like a TV remote); however, their practical use is debatable.

Symmetric Packs

The next step up is to use a symmetric pack with a pack head. Note that you cannot plug a mono head into a pack. A pack head is essentially a “dumb” unit that only houses the flash tube and modelling bulb, and a fan to cool both. The pack head has a cable (usually about 5m long) that will plug into your pack. You must never plug one brand flash head into a different brand flash pack. If you do, you will very likely blow up the flash head. The typical Symmetric pack has only one control for power, so if you have one head or three plugged in to the same pack, you will only be able to distribute the power evenly over each head. You cannot divide the power up unevenly.

For example:

If you have a 3000w pack, then at full output, with three heads plugged in, you will be distributing 1000w through each head.

In the same example, if you had only two heads plugged in, then you would divide the output in half, distributing 1500w per head.

If you dial your power down, then you will still be splitting the output evenly across all the heads.

The downside to using Symmetric packs is that if you do want to vary your output per head, then you are limited to moving your heads closer or further away, or using ND (Neutral Density) filters on your light modifier to cut your light output. This is a slow and often annoying practice.

The other negative effect of moving heads physically closer or further away from your subject is that the light effect from your modifiers will change. If, for example, you wanted to use a small softbox at 1m from your subject but found that you needed to reduce your output on that head, you could move it back an extra 2m, but this would change the light effect. To maintain the light effect, you would ideally change to a medium softbox, and so on … Alternatively, you could use one pack per head, so that you can get individual control over each head. This is, however, a costly and rather redundant idea for most photographers.

In the two images above, you can see that using a Symmetric pack with two heads, we have had to move the softbox back 1m to reduce the output by 1 stop from the first position.

Asymmetric Packs

Finally, the ultimate solution is to use an Asymmetric pack. With these you can individually adjust the output on each head.

For example:

If you were using a 3000w pack, with three plugs, you could set one head with 100w, the second with 1626w, and the third with 300w… or any kind of variation, as long as you don’t exceed the total output.

While Asymetric packs are often the most expensive to buy or rent, it may mean that in effect you can manage with only one pack, less light modifiers, and you will definitely save time. Modern Asymetric packs are all digital, allowing adjustments in 10th/stop increments.

Digital Asymetric packs also offer the most sophisticated enhanced controls/features, such as flash duration control, colour temperature management, intervalometer, etc.

ps: If there are any readers who would like specific lighting issues discussed, please email me, and I will try to work it into the articles this year.

adam @ custins.com

pps: for the sake of simplicity, I have used watts as the measure of power. There are 1000w in one kilowatt, therefore 1k = 1000w. The terms are interchangeable. Also in such discussions, joules can be interchanged with watts (as in the digital readout: it says, eg: 400j which = 400w).

All photos Adam Custins

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