Flash 101

Photography

Flash Systems -101

(Primary Flash systems; Elinchrom, Profoto & Bron)

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In simple terms flash is created by releasing stored electrical energy between two points. Thesetwo points (anode + and cathode -) are within a quartz or pyrex envelope of Xenon gas and theenergy released is heat and light. This energy is stored in capacitors within the flash unit. Thecapacitors are reservoirs of power, which are filled form the mains supply. Once full, the powerthey store is prevented from passing around the flash tube by the inherent electrical resistanceof the Xenon gas. Around the outside of the flash tube is the trigger wire. This is a fine wirealong which is passed a high voltage but low current pulse (around 24,000v). This causes thegas within the flash tube to ionise thus reducing its resistance. The stored power is thenreleased through the tube to create the flash.

100%

IB

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Time

This is a diagrammatic representation of flash. Notice that the lamp reaches peak power almostinstantaneously before decaying at a proportional rate. The sharper (steeper) the curve, theshorter the flash duration.

Flash duration is measured in terms of the time it takes the light energy to dissipate to a specificlevel. In this particular case it is t=0.5, that is the time it takes this lamp to dissipate from fullpower to 50%, i.e. from the point of correct exposure (100%) to one stop below correctexposure (50%).

Although t=0.5 is the generally accepted standard for reading flash duration you may also seelonger durations stated also, e.g. t=0.2 (20% some Profoto), ort=0.1 (10% Broncolor, and someBowens).

In addition, the slope of a flash curve is also an indication of colour temperature. The steepercurves indicate a blue cast; shallow curves indicate a yellow cast.

Flash lighting is the main type of artificial lighting used nowadays by professionalphotographers. Although many photographers still use continuous artificial lighting such astungsten or HMI the vast majority of photographers use flash light.

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All of the main European manufacturers Balcar, Bowens, Broncolor, Elinchrom, Hensel,Multiblitz and ProFoto produce similar flash lighting equipment in the three main areas of design- generator packs, battery packs and monoblocs.

Generator packs are units designed to run from a mains electricity supply and generally range inpower from 1200J to 2400J to 4800J although some are 6000J and more (many are also 1500J,3000J 'etc'). The capacitors that store the electrical energy are built into the generator packwhich means that the flash head is very small and compact.Generator packs distribute the power either Symmetrically (each head receives the sameamount of power, e.g. a 1500J pack with one flash head gives 1500J to that flash head, but withtwo flash heads gives 750J to each flash head and with three flash heads gives 500J to eachflash head) or Asymmetrically (each flash head can receive different amounts of power withinthe total range of power) and a few generator packs are both Symmetric and Asymmetric.Apart from the distribution of power and the amount of power itself generator packs tend to offermore control of the flash power (often down to 1/10 of an F-stop over a seven F-stop range),flash duration (down to as little as 1/7500 sec) and colour temperature control. Some can beprogrammed to trigger a sequence of flashes, memorise set-ups and to even be controlledwirelessly from a computer.Generator packs are the equipment of choice for the studio photographer as they allowcomplete and subtle control of the flash light as well as large amounts of power.

Battery packs are portable units designed to be used on location powered by a rechargeableacid gel battery. These units allow the photographer to work on a beach, in a field 'etc' and stillhave adequate power and fine control over the power (some offer 1/10 of a Stop fine control).Most batteries will give about 150 flashes at full power (at full power flash recharge times can bevery slow, maybe 5 or 6 seconds) and obviously many more at half or quarter power. Adrawback with battery power is if the ambient temperature is very cold the batteries will losepower, therefore it is very important to have spare batteries when working on location. Allbattery packs can also accept an adaptor so that they can run from the mains electricity supply,this enables quicker recycling times and in some cases a slight increase in power. Most batterypacks only allow two flash heads to be attached to the pack.Many editorial photographers find that a battery pack, two heads and a mains adaptor issufficient for all that they need as they are mostly on location and often only have a shortamount of time to photograph their subject and that the battery pack is quick to set-up and easyto transport.

Monoblocs are all in one self-contained units. The capacitor and the flash head are in the sameunit. Monoblocs range in power from 250J to 1500J and as the power increases the physicalsize of the unit increases. Although monoblocs do not have the same level of sophisticatedcontrol as the top-range generator packs (flash duration and colour temperature cannot bealtered) they still offer a 5 stop power range and many do this in 1/10 of an F-stop increments.Monoblocs are also reasonably portable although they only work from mains electricity.

Many photographers work both in the studio and outside in the world on location and ideallythey would like one system of lights that does both. A studio based photographer could runhis/her mains powered generator pack on location from a petrol powered generator but this canbe awkward and problematic. Alternatively a battery powered pack can run inside on mainselectricity via an adaptor but this limits the photographer to only two flash heads and limitedcontrol. Bowens now market a monobloc system called the Gemini which works conventionallyfrom the mains supply but, uniquely, these monoblocs (500J and 750J) can also be powered bya Bowens battery called a Travel Pak (they have another battery powered pack called anExplorer 1500 that can accept two standard Quad heads as well as two Gemini 750J headsmaking a total of 4 heads and 3000J on location). At the other extreme is the Broncolor VersoA2 this is a 1200J mains powered generator pack that can accept a special battery which allowsfor between 350 to 450 full power flashes for location work. This pack allows all the


sophistication of studio generators (asymmetrical/symmetrical, 1/10 stop power control, varyingflash duration, altering colour temperature, sequencing flashes 'etc') to be used outside onlocation.

C3C3 elinchrom

eiinca &a Switzerland www.Giinchrom.com

Elinchrom generators are some of the most widely used and the most widely owned flashsystems in the U.K.

Direct Lighting holds substantial stocks of Elinchrompack and monoblock systems. Packs are available inthe older 1000w/s (Rapid), 2000w/s (202), and 4000w/s(404) models. As well as the newer Classic 1500, and3000 packs. There is also a 6000w/s model available onrequest. All early and late Classic packs aresymmetric, and DO NOT feature an audible chargewarning (ready light only!). In addition Direct LightingElinchrom packs have been adapted to accept bothstandard mono jack plugs, and Elinchrom threadedsync cords. This is important to remember if ever you

need to 'hard sync' packs together as you will need both types of lead. Spare thermal fuses forthese packs can be located in the well of the pack-carrying handle. The fuse sockets are on thecontrol panel of the pack itself.Elinchrom equipment has always been comparatively simple to use, which has been themainstay to their popularity over the years. However, particular caution is required when usingthe older 404 (4000w/s) Pack. When using this particular pack on 13Amp mains be sure to useonly one pack per ring main. Otherwise you may experience common problems such as mainsand thermal (pack and head) fuses blowing or flash heads firing without you actually triggeringthem. It should be noted that this is not a problem exclusive to Elinchrom packs. But because oftheir high current draw you are most likely to experience this problem with these packs.

There are various heads available for thesepacks. Direct holds stocks of A3000 (3000w/s)and A4000 (4000w/s) fast duration standard

^- heads, as well as R3000 (3000w/s) and R4000(4000w/s) linear flash heads, and X8000(8000w/s) bi-tube/twin-heads. All of these flashheads have their own thermal fuse located inthe top, or base of the head.

It is important to remember to match the rightElinchrom flash head to the right pack. You may use a high output head (e.g. a A4000 head),with a low output pack (e.g. a Classic 202 Pack). But NEVER the other way round! You willblow the flash tube and risk ruining the head itself.

Direct also holds stocks Elinchrom monoblock heads. Available in either single or 2 head kits, inoutputs of 500w/s, 750w/s, and 1500w/s. As with the packs, Elinchrom monoheads have NOaudible flash warning, but do have built in white light slaves. All our stocks of these heads havebeen adapted to accept standard mono syncs rather than Elinchrom syncs.

All Elinchrom Classic equipment is single voltage. In the case of the U.K. this means240v/50Hz only.


Direct holds the largest stock of Profoto equipment available for hire inEurope. The main reason for Profoto's popularity over the years, it is atotally modular system that is easy to understand and easy to work with.Profoto products are generally fast, simple to use and reliable. AllProfoto heads have a unique 'zoom' accessory fitting which allows youto move your chosen reflector backwards/forwards on the lamphead.

Profoto Acute2 Generators

Smallest of the Profoto generator systems is the Acute2. Availablein 1200w/s (2400w/s on request), the system has been designedspecifically with worldwide use in mind. Both generators areextremely light, the1200 version weighing only 4.3kg (comparedwith 8.9kg for an Elinchrom Classic 1500 generator!). Both packsare asymmetric with a maximum range of 7 stops adjustable in %stops. The shortest flash duration possible with this system is1/3200sec on the 1200 pack, and 1/1800sec on the 2400 pack.

As with all Profoto equipment the Acute2 system is a true multi-voltage pack, meaning it can be used anywhere in the world witha mains supply. The adjustment for this can be located underneath

the handle of the pack. There are 2 switches for this, the voltage selector, and the frequencyselector. Both must be set correctly or the pack will not work properly/switches off after 5sec.The modelling light is powered directly from the mains supply, so will need to be changed whenworking with 110v-127v power sources.

Acute2's have their own range of flash heads, the AcuteHead (max.2400w/s), the Acute-Twin bi-tube head(max.4800w/s), and the Acute Ring-flash(max.9600Ws/minute). Acute heads are compatibleONLY with Acute packs; Acute heads CANNOT be usedwith any other Profoto generator. All Acute heads andhead-to-pack cables hired from Direct will be colour-coded

Profoto ProPack Generators

Profoto ProPack's are one of the simplest mains packs to use, and are symmetric only. Theyare a self-seeking (automatic) multi-voltage pack, this includes the modelling lamp. TheProPack has an output of 1200w/s adjustable in 1/3stops over a 5-stop range. Minimumduration for this pack is 1/4400sec, with a minimum full recycle time of 1.1 sec.

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Profoto Pro6a, and Pro7a Generators

Pro6a, and Pro7a packs offer a much higher level ofcontrol compared to the Acute, and ProPack systems.These packs are available in either a 1200w/s or 2400w/sversions. The Pro6a and Pro7a generators areasymmetric.All of these packs are self-seeking (automatic) multi-voltage, with the exception of the modelling lamps forPro6a 1200/2400 packs. These packs only must bevoltage corrected by using the slider switch under thepack handle.Profoto 6a and 7a generators are designed to offer anextreme fast flash duration; 1/7500secfor Pro6a 1200w/s,1/5300sec for Pro6a 2400w/s, and 1/8000sec for Pro7a2400w/s. And an equally high speed recycle rate; 0.11-

0.70s for Pro6a 1200w/s, 0.12-1.35s for Pro6a 2400w/s, and 0.12-1.40s for Pro7a 2400w/s.All 3 of these generators have a 6-stop range, adjustable in either 1/6 or 1/3stop increments.

There are a number of other features unique to the Pro6 and 7 asymmetric series, making themindispensable for fashion and editorial work. In addition to the fast recycle feature offered bymost pack systems Profoto offer an extreme fast TURBO recycle option, where it is possible toachieve flash durations of up to 0.11 sec. It should be noted that this is not a permanentlysustainable mode. The current draw involved when the pack is set to TURBO is vast. Thereforeto protect the flash tube from blowing, the pack will drop back to standard recycle mode whenthe pack/head starts to overheat. When cooled sufficiently the pack will automatically switchback to TURBO again.

The Master control allows you not only alter the output of each channel simultaneously, it alsoallows you to control the colour temperature of the flash output. Each 'click' on the control willalter colour temperature by 50°K. Turning the control counter-clockwise will move the flashoutput to the warmer (yellow) end of the spectrum. Turning the control clockwise will move theflash output to the cooler (blue) end of the spectrum.

In addition, along the bottom of the Master control is an Auto-Bracket mode. To activate this, setthe control within the Auto-Bracket box at either 1/3,1/2, or 2/3 as desired. To activate releaseone 'open' flash, the first exposure after this will be normal, the second overexposed, the thirdunderexposed, and the fourth will be normal again. As long as Auto-bracket is set, the cycle willcontinue.


Profoto Pro7b Battery Generators

Profoto battery systems are 1200w/s, adjustable in 1/6 stop over a 7-stop range. For a battery system, they offer a relatively high flashduration of 1/3000sec combined with a recycle rate of 0.09-2.80sec.Pro7b packs are switchable between symmetric and asymmetricmodes.Because this generator is battery powered, depressing the model lampcontrol on the pack will turn the lamps on for 20sec only. You canincrease this by pressing the control more than once (2 presses = 40sec,etc.). The maximum time the lamp will stay on is 60sec. For every 20secthe lamp is on, battery power will decrease by the equivalent of 2 flashesat full power.

Profoto batteries are a nil memory effect type. They can be used at any time without being fullycharged. Batteries take 3.5hrs to be fully charged from the mains, you can charge them byeither plugging the Rapid Charger unit directly into the battery or through the pack itself.

All rechargeable battery's, Profoto or not, are effected by usage and environment. The cold willeffect a battery's recycle time and life span, as will the length of time the battery has been 'offcharge', and how much you have used the model lamp. During average use you should expecta fully charged battery to last for about 80-100 flashes at full power.

In addition to the Rapid Charger, a Car Charger is available which works directly through thepack only (full charging time is around 6hrs for the car unit). There is also a multi-voltageUniversal Mains Adaptor, which allows the Pro7b generator to be run from the mains andcharge the battery at the same time.

Pro7b flash heads are NOT compatible with any other Profoto generator system. They do notcontain cooling fans, using convection to cool the flash tube instead. Profoto mains heads (NOTAcute/2 heads!) can be used with the Pro7b pack but the modelling light will automatically bedimmed down to 100w regardless of output.

Running a mains pack from a portable petrol generator

Profoto ProGas Generator Adaptor

Profoto light systems are the only flash packs Directrecommends for use on all petrol/diesel generators. TheProGas adaptor is designed to protect the flash equipmentfrom power surges that can result from using a generator.The adaptor is used in-line between the flash pack and thegenerator, and will keep drawing power, even when the

flash pack is not. This establishes a 'bench', continuous current draw on the generator. Whichwill help eliminate the possibility of a power surge. ProGas adaptors must be used one-per-packwhen running Profoto equipment from a genny.


I broncolorBroncolor manufacture some of the most versatile flash systems available. As assistants,Broncolor mains pack's are the most complicated flash systems that you're likely to use.

Broncolor Grafit A2, and A4 Generators

Direct holds stocks of both Grafit A2 (1600w/s), and Grafit A4 (3200w/s)mains packs. Both of these packs are fully asymmetric. In addition theyare also dual-voltage. The voltage selector is located on the control panelnext to the sync sockets (Check you have a corresponding modelling lampinserted first!).

Grafit packs offer a number of features, which render them useful in bothfashion and advertising photography. Both packs are capable of minimumflash duration of 1/10000sec. With a pack range of 6 7/10 stops adjustable

in either 1/10 or 1/3 stop increments. Individual 'channel' outputs can bedisplayed in either Joules (w/s) or in %. %

Grafit are one of the few systems to offer colour temperature stabilisation,in effect you can set the pack so every flash is exactly the same colourtemperature. In addition Grafit systems can be programmed to producesequences of up to 50 flashes with variable rates of delay. There is nothermal fuse for these packs instead they incorporate a circuit breaker, the'reset' for which is located underneath the main on/off switch. The slavesystem in Grafit packs is triggered by infrared and white light.

There are types of head available for* jj the Grafit system, Pulso F/G heads

;_ „ (3200w/s), and Pulso-Twin (6400w/s)bi-tube heads. The heads themselvesincorporate a thermal fuse, located onthe top on the head. Pulso G headshave a similar 'zoom' control to

Profoto. A thumb-wheel on one side of the lamp will move the model lamp and flash tubebackwards/forwards inside the lamphead. Both lamps incorporate a glass UV protection cover.DO NOT use the lamp if this is damaged/not in place. Both of these heads can be used withBroncolor Mobil battery pack, however the modelling lights WILL NOT function if used this way.

Broncolor Mobil Battery Generators

Mobil is Broncolor's battery flash system. The pack will output1200w/s from battery, or 1600w/s if the pack is used with a mainspowered Mobil Studio Booster.The model lamp works in 20sec cycles, i.e. pressing the control oncewill turn the lamp on for 20sec, twice = 40sec, etc.The Mobil pack is totally symmetric, and adjustable in 1/10 stopover a 5 stop range. The minimum flash duration possible on theMobil is 1/1100sec, with a recycle time 1.50-6.00sec.

As with Profoto battery systems, battery life is totally dependant on usage and environment.During average use batteries should last 70-100 flashes at full power.


Useful Contacts

Studio Hire:Chris Fairchild, Studio ManagerTelephone: 020 7490 5965Email: [email protected]

Equipment Rental and Consumables sales:Lloyd Barker, Camera and Consumables ManagerTelephone: 020 7014 5000Email: [email protected]

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Flash 101