I thought it might be interesting for some of you if I explain how this image of a tennis player diving for the ball was created, starting with the concept and working through to the the post-production.

Concept

Once the initial idea for the photo had been conceived (and having the idea is often the biggest challenge) the first step was to determine exactly how to achieve the result.  In this case I clearly couldn’t ask a model to dive onto a real tennis court (that’d hurt I would think…), so the only option left open to me was to produce a composite image.

As with all commercial-style shoots it’s important to pre-visualise the final image since this will guide the choice of location, the model, the clothing, etc. In the case of a composite image this pre-visualisation becomes absolutely critical; if the result is to be successful each of the individual images needs to be taken under similar conditions.  If the perspective of each subject isn’t consistent, the depth of field doesn’t match or the lighting is too different then the final result won’t be convincing.  It’s not feasible to undertake a project of this nature without having a good idea of what the final image will look like.

Planning

I knew that I wanted to use a wide angle lens with the tennis player close to the camera for a more dramatic perspective, and this implied a number of important considerations:

• I would need a very wide chroma key (“green screen”) backdrop.
• I would therefore need a fairly large studio.
• The perspective distortion would be strong, so it would be very important that the photo of the tennis court be taken at the same focal length as the photo of the player so that I could place the player at the correct distance into the image.

Unfortunately I didn’t have access to a green screen as wide as I needed, so I had to improvise.  I ordered a 1.2m x 15m roll of “Fadeless Art Paper”¹ so that I could stick it up on the wall using masking tape.  I didn’t expect this to be ideal (and I was right!) however I was prepared to spend a little more time in post-production to work around any problems.

Other than the backdrop issue there were many other things to think about – even a small scale shoot like this one needs careful planning.  Here’s an non-exhaustive list of the things that I needed to consider or remember to bring along:

• The date and time: the studio, the model and myself all needed to be available at the same time.
• The camera equipment: which lenses and strobes would I need to bring along? I have a very long equipment check list that I use when planning a shoot.
• The model’s comfort: food and drink (I made a quiche), access to toilets, a place to change, etc.  Also, in this case, a mattress to land on!
• Setting up: It’s the simple things that are easy to forget – masking tape, scissors and a step ladder for  putting up the backdrop for example.

The “Dive” Shoot

The "dive"

I planned to give myself an hour of set-up time before the talent arrived, however I was lucky enough to find a great model who wanted to be involved in the whole process.   She arrived early to help me unpack the car and prepare the equipment.  Without her help putting the backdrop in place would have been a horrendous experience – thanks Selma!

I’d bought 2 mattresses and a thick double duvet to use as a landing pad.  I positioned these at the angle that I wished to take the photo and moved them as far away from the “green screen” as I could.  The combination of a wide angle lens, a very wide subject (model horizontally out-stretched with a tennis racket) and close shooting distance meant that I couldn’t get as much separation as I’d have liked, so the green would inevitably “spill” onto the model and increase the post-processing time.  The main light also cast a shadow on the backdrop (although that isn’t too hard to handle later).

The lighting setup was fairly classic.  I used two monobloc flashes to light the backdrop as evenly as possible.  The main light was a Profoto AcuteB with the “New Zoom Reflector”, placed just left of camera and just high enough to put a catch light in the model’s eyes.  I planned to use another AcuteB as a fill light but it wasn’t necessary in the end (the white walls did that for me).  Rather than let it go unused I was able to use both power packs together for the main light (a dual tube Acute “Twin” head) allowing me to reduce the flash duration to better freeze the model in mid-air.  Finally, a Canon 580EX with a C.T.O. gel used as a kicker gave a slight separation.  All the flashes were set off simultaneously using PocketWizard radios.

After an hour’s set-up time we were ready to shoot.  Once again I was lucky to have been blessed with a great and enthusiastic model.  She took a 10 minute jog to get the sweat going a little, and then proceeded to take 70 (yes, seventy.) dives onto the landing pad.

My 5D MKII was tethered to my Macbook Pro, and the images were bought into Lightroom² so that she could see her body position and facial expressions.  This sort of direct feed back really helps to get the talent involved in the shoot, helping them to help you.

At the end of the shoot I took an image of a tennis ball under exactly the same lighting conditions.  This would facilitate the composition later on.

The “Tennis Court” Shoot

The tennis court

The choice of court would have an huge effect on the final image.  Since I wanted a slightly gritty/hard feel to the image I found a court that would suit that look.

The light falling onto the court was very flat – not at all like the hard light falling on the model – but that actually gave me more opportunity to control the image in post-production, and for the look I was after the flat light was more appropriate.  Had I wished for more lighting consistency it would have been crucial that the light was coming from the same direction as the light on the model (and that would have cast my shadow on the ground, complicating things a little).

The only major shooting considerations were therefore the focal length and aperture (which needed to be the same as that used in the studio), the focal point and the angle of view.

Post Production

I personally use Lightroom to catalogue and rate my images, so the very first step was to bring the images into my main catalogue. Once this was done I selected the images that would be used in the composite.

To choose my selects I use an iterative process.  On the first run through I give one star to all the images that have any possibility of being selected (in this case filtering out the ones where there model has already landed or where she wasn’t placed correctly in front of the green screen, etc).

I then filter for only these images and go through again to find the 2-star images – this is possible now that I have a familiarity with all the images in the collection.

In the third iteration I find the best images from the collection and I also check for critical focus.  If necessary a fourth iteration will leave me with just a few images to select from.  For this shoot the body position and facial expression were the two most important criteria.

Once I had my “dive” shot selected I bought it into Photoshop to remove the green screen (and the green spill).  This is a critical step, a badly cut out image will destroy the final effect.  Delivering a well-executed composite image requires a fair amount of post-processing experience and familiarity with your editing application (Photoshop in my case).

The tennis court also received some retouching to remove the fussy background. I wanted a clean image in which there weren’t lots of details fighting for the user’s attention.

The resulting composition is achieved using a fair number of layers in Photoshop.  Good use of layers ensures that the composition is created non-destructively so that it can be tweaked until it’s right.  The three principal images (court, talent and ball) are included as smart objects so that they can be transformed and retouched many times without compromising the image quality.

Here’s a look at the resulting layers palette to give you a feel for the work involved. Bear in mind that some of the work isn’t visible here since it’s inside the smart objects (the green-screen masking, for example).

Note that it’s best to read from the bottom up.

Attention to detail is essential if the composite is to look real to the casual observer. Things such as the subtle colouration of the ball and t-shirt from reflection of the ground help to ensure that the result is as seamless as possible.

Over to you…

I hope that this has been a useful insight into a shoot of this type.   There are many things to consider and to control, but this is what makes photography so interesting!

If you’re interested in learning more about photo realistic composition then you may be interested in the workshop that I’m going to to start offering for 2010.

If you have any questions then please feel free to leave a comment so that others may benefit.

1. This was harder than it should have been since I couldn’t find such a thing in France so I had to order from the UK.
2. Tethered shooting is possible using a combination of EOS Utility and Lightroom

To this end, over the course of the last few weeks I’ve been doing a lot of research into the various options that are on the market. Unfortunately I couldn’t find any resources on-line that grouped all facts together to help make the decision easier, so I’m sharing the fruits of my labour in the hope that it’ll serve other photographers.

Updates

I shall continue to update this post retrospectively to fix any errors or to add new information that I deem pertinant.

History

28 May 2009: Added importance of minimim flash duration to the discussion.
26 May 2009: Added flash duration for Acute Twin head, and discuss the use of two AcuteBs as a great starting setup.

The Contenders

There are battery powered flash systems available from all the major flash manufacturers, including Profoto, Elinchrom, Hensel, Bowens, Bron, White Lightning and Alien Bees. However, since Paul Buff’s White Lightning and Alien Bee systems are not readily available in Europe I eliminated them from my research. I also eliminated Bron since they’re far too expensive. That left Profoto, Hensel, Bowens and Elinchrom.

Criteria

In the comparison that follows I’ve compared the specifications of the various options available.

When considering a flash system some of the most important factors, price aside, are the power, flash duration, recycle time and the weight of the system, so I’m going to take a quick detour to discuss these points. The one thing that I don’t talk much about in this article is price – each photographer will have their own budget to consider.

Power

How much power should a portable flash have? This is a key question to answer when choosing a system because it’s going to have a direct consequence on the weight, and therefore the portability of the battery pack.

Questions to ask include:

Will you be shooting at the brightest time of day?
Will you need to overpower the ambient light, or are you just wishing to supply fill?
Will you be using a softbox or a reflector? Softboxes will require more light.
Will you be shooting in confined spaces or with wide apertures; will you need to turn the power right down?

To overpower sunlight using a softbox at 2pm in the afternoon on a bright day, you’ll need power, and you should definitely be looking at a system offering 1000Ws or higher. Most people consider 600Ws to be borderline for overpowering the ambient light, but depending on your shooting style this may not be an issue, in which case the 600Ws units are more portable and less expensive.

A good alternative would be to invest in a 600Ws system that offers a bi-tube flash head. When you need 1200Ws (or a shorter flash duration) you can put two packs together. When you don’t, you have more flexibility in the placement of the packs, and the ability to travel with half the weight when only one light’s needed.

Having lots of power isn’t necessarily a good thing however. Often the more powerful flashes don’t have a power range that allows them to be fired a very low power. The Bowens Explorer 1500 is such an example – it offers 1500Ws, but can’t be fired at less than 31Ws. When working with wide apertures or in circumstances where the light can’t be moved further back, the minimum power level can quickly become a real problem. I often stumble into this when using my 600Ws Bowens Geminis in the studio – their 6 stop range is limiting on the lower end. The problem can of course be address using ND filters, but it’s a pain.

Flash duration

If you need to freeze action then a short flash duration is absolutely essential. The manufacturers typically quote the ‘t0.5′ value for the flash duration, which is the total time that the flash output is above 50% of its maximum for a given power level. To equate the flash output to an equivalent shutter speed (for freezing action) we really need the t0.1 value (the total time that the flash output is above 10% of its maximum), and we can fairly reliably calculate this by multiplying the t0.5 value by 3.

For example, a t0.5 flash duration of 1/3000s is approximately equivalent to using a shutter speed of 1/1000s as far as freezing action is concerned.

The duration of the flash is dependant on the power level chosen. It is generally quoted that, in the case of portable strobes such as these, the shortest flash duration is achieved at the lowest power level, and the longest at the higher power level. This being the case, overpowering the sun (high power requirement) and stopping action (low power requirement) may be mutually exclusive.

During my research however, it’s become clear that not all the power packs behave in accordance with this rule. In effect, as the various capacitors are switched in and out to achieve the desired power level, this has an effect on the flash duration that’s difficult to predict. For example, the Bowens Explorer 1500 has its shortest duration at 1000Ws, and the Hensel Porty 12 at 300Ws. Also of note is that on asymmetric packs the shortest flash duration will normally come from the lower powered output.

Unfortunately this level of detail isn’t readily available. I’d be happy to add flash duration curves to this article if my readers can provide the raw data.

Recycle time

This is simply the time that it takes for the strobe to recharge ready for the next shot. Clearly, it’ll take longer to recharge when shooting at full power than it will at low power.

If your shooting style is fairly slow then this will probably have little bearing on your final decision, however if you’re shooting action it can be the most important criteria when choosing a pack.

Weight

The weight of the pack may well be very important for you. If you working alone and moving about a lot then a low weight system will have a huge advantage. A small flash pack that you can put into a backpack is a lovely thing to have.

On the other hand, if you’re doing large commercial shoots and have assistants and transportation at hand then the advantages of the larger packs will probably outweigh the weight disadvantage.

For this reason, many photographers may eventually choose to go both ways and buy different pack for different uses, and this foresight may well influence the buying process:

• Does the manufacturer offer both heavy and lightweight systems?
• Are both these systems appropriate for you?
• Are the modifiers compatible with both systems?
• Are the heads compatible with both systems? Is that important to you?

Facts and Figures

I shall start with a direct comparison of the fact and figures since they’re easy to compare. They don’t tell the whole story however, so I will follow with a more subjective comparison afterwards.

To make this comparison fairer, I’ve divided the various product lines into two groups – those of less than 1000Ws, and those of 1000Ws or more. If we don’t do this then many of the figures become meaningless; for example the Hensel Porty 6′s stunning 1s recycle time is very impressive when compared to the Elinchrom Ranger’s 3 seconds – but of course it only has to reach half the power…

Packs offering 1000Ws and higher

Packs offering less than 1000Ws

Other considerations

If there were one flash system that stood out as the clear leader then that would certainly make the buying decision a lot easier. Unfortunately this isn’t the case. Each product range has its advantages and disadvantages, and there’s always a compromise to be made.

Aside from the compromises that can be seen from the above tables (power vs weight vs performance) there are other things to consider too. Here I’ll look at each system and add my own subjective viewpoint.

Bowens

The Bowens Explorer 1500 battery pack offers excellent value for money, and may well be the best compromise for a number of people. The Bowens system itself is very extensive and their innovative “Wafer” softboxes are considered by many to be the best of any brand.

Pros

• Very short flash duration (1/5700 at 1000Ws)
• Very reasonably priced
• Highest power output available (1500Ws)
• Full asymmetry – both heads can be controlled independently.
• A total of 4 heads may be attached – 2 QuadX’s and 2 Gemini Esprit monoblocs

Cons

• Noisy fan
• Slow recycle time
• A friend of mine who uses this system tells me that RF noise it emits interferes with (US) Pocket Wizard reliability. Need to use Pulsars instead.
• No lightweight portable system alternative (TravelPak requires Gemini monoblocs)
• No option to remotely control the power levels
• Minimum power level is high (31ws), which may be annoying when working at wide apertures

Elinchrom

Elinchrom offers what is arguably the best overall system in terms of interoperability. The Rangers offer good performance with a much lower weight penalty than either Profoto or Bowens and at a reasonable price. The Quadra’s compliment the Rangers very nicely when portability is essential, and the Ranger heads can be used on the Quadra. Furthermore, the Elinchrom modifiers are plentiful and very well regarded.

That all said, most users appear to strongly dislike the mounting system, describing it as fiddly and error prone. There are plenty of stories of softboxes falling off because they weren’t attached properly! Also, the Elinchrom range stops short – when the Rangers don’t have the recycle time that you need, there’s no top-end product to turn to.

Pros

• Excellent all-round system
• Good choice of modifiers
• Reasonably short flash duration
• Light weight
• Skyport system allows for remote power adjustments
• Battery change is quick and efficient – very well thought out
• Weather resistant thanks to sealed push button interface

Cons

• Build quality often considered lower than the alternative – may be a little more fragile
• Slow recycle times
• Very fiddly mounting system
• Digital interface less convivial than analogue knobs (personal opinion)
• No very high-end portable offerings

Hensel

The new Hensel Porty stands apart from its peers due to its Lithium battery technology. Using Lithium rather than Sealed Lead Acid gives the Porty some major advantages in weight and recharge times.

If portability is the most important feature for your shooting style then the Hensel will be a great tool. The Porty 6 out performs the competition easily. However, if you’ll eventually need more performance then there are no options in the range that’ll match the Profoto B2, so this could be limiting.

Pros

• Very low weight
• Very quick recharge time
• Very fast recycle times
• Excellent flash duration for the Porty 6
• Hensel radio system allows for remote power adjustments
• Weather resistant thanks to sealed push button interface

Cons

• Mediocre flash duration for the Porty 12 – especially when looking at the other advantages. A real shame that they couldn’t do better here.
• Digital interface less convivial than analogue knobs (personal opinion)
• Uninspiring range of modifiers
• Less common, so harder to find accessories etc.
• Spare batteries are very expensive

Profoto

When reading forums and talking with other professionals Profoto stands out as the brand of choice. Profoto products are expensive compared to the other brands, but they’re renowned for their build, reliability and superb light quality.

All is not rosy however. As a complete system I feel that Profoto is somewhat behind its peers. The AcuteB offers great portability, but the autonomy is poor and the recycle times and flash durations are very poor compared to the Hensel Porty 6. They’re also limited to just one head, and that head isn’t comptable with the other products such as the B2 or 7b, so if budget is tight it’s going to be hard to build up a system gradually. Finally, none of the battery packs are currently compatible with Profoto’s “Air”‘ system for remote power adjustment.

Do they have any redeeming features? Yes, of course. In terms of raw performance the B2 is the absolute best in class with the fastest recycling time and the shortest flash duration, although the price one pays for this is the weight. Moreover, they have what is undeniably the best mounting system. It’s quick and easy to use, and it allows for the reflectors to be “zoomed”. By moving a reflector back and forth the spread and quality of the light changes, giving the creative professional a wealth of possibilities that simply don’t exist with the other brands. It’s possible to change the fall-off of light in a way that would be very difficult in any other way.

All this is very infuriating. With Profoto you get both the best of what’s on offer (performance, build, superb mount) and the worst (price, system limitations, no remote power control) in one package, and you have to pay the highest premium for it.

If budget isn’t an issue then all things considered, Profoto is an excellent choice because it’s the system that has the most room for expansion (e.g. when you need more speed, there’s a pack that offers it). If you have the means to buy into both head systems then the system disadvange goes away. However if budget is an issue then think carefully before investing.

A single B2 is a great place to start, but the 7b represents awful value for money, offering very mediocre flash durations and recycle times.

Another excellent starting point would be to buy 2 AcuteBs, one with the bi-tube (Twin) head. This set up offers a great deal of flexibility – the two heads are totally independant for complete control and less cable routing problems. When portability is paramount one pack is very light to carry about. When more power, quicker recycling times or shorter flash durations are needed then the two packs can be used to drive the Twin head.

Pros

• B2 offers best in class performance
• Very high build quality
• Easy to rent
• Best mounting system by far (can aslo accept adapted Elinchrom modifiers)
• Excellent range of modifiers

Cons

• Expensive
• B2/7b packs are very, very heavy
• No radio system for remote power adjustments
• Not at all weather resistant – care needs to be taken.
• The AcuteB is poorly spec’d compared to competition equivalents
• B2 is best in class, but also heaviest
• Acute and Pro heads aren’t interchangable

Conclusion

All the systems that I’ve looked at have their own advantages and disadvantages. There’s no one brand that stands out as the obvious choice, and each photographer will have his or her own specific needs. It’s an unfortunate reality that it’s very unlikely that any of the systems available today will meet all of them. For example, I’d ideally like a small, light weight, 1200Ws pack that offers a very short flash duration and an extremely fast recycle time. In practice I can have all of those things, but not in the same package.

Given the sums of money involved I feel that it’s very important to take time to examine the various offerings and to make an informed decision based on your own requirements. Many forum discussion include comments along the lines that the light quality is essentially the same from all of them, and that all the systems will do a great job. Such commentry may be true for the person stating his or her opinion, but don’t be so blindly led. You may be very happy with your Elinchrom Ranger until the day that the 3s recycle time drives you mad and there’s no better option to upgrade to. You may love your Profoto until you realise that you need another light and you can’t afford it. Hensel offer a great package – but can you get parts easily where you live?

My advice is simple: consider not just what you want to do with the flash now, but also what you’ll do with it in the future. Look at the whole system, be very aware of the compromises that you have to accept, then decide.