Stuart,
These kinds of specs are really hard to achieve. You could use lens design as an example... with camera optics, lens designers have to balance several factors and make certain trade-offs. Center sharpness, edge sharpness, light gathering, CA, distortion control, coma, astigmatism, macro-contrast, micro-contrast, color rendition, flare suppression, bokeh, size, weight, feel, and, oh yeah - cost to make and how many they can sell at that price.
Top end studio lighting is very similiar to this. The Pro-8a was designed as a no sacrifice pack. In the past, you could have a fast, powerfull pack with quick recycle and short duration but limited control and okay color stability, or you could have a very color stable pack with more control but so-so recycle speed and duration, etc.
To put all the elements together like this is very, very difficult. The 8a has less color and power variation than the D4, which is one of the best out there. Shot-to-shot power output is only +/- 1/50th of a stop! The most accurate hand-held meter can't even detect this difference. The color shift from 2400 W/s to 150 W/s is just 50 deg K, which you probably can't see without a digital color meter. It is 50% faster in recycle than the 7a, which is again one of the fastest. 0.9 seconds to 2400 W/s is really, really fast and <0.5 seconds is just plain rediculous for 1200 W/s. I've never seen a pack that has a 10 f-stop power range before, let alone one with 1/10th increments. That means you can go from 1/1 to 1/1000 power, with 100 levels of precise control. That means f/2.8 to f/90, as an example. The flash duration is as short as 1/12,000 sec and still only 1/1,600 at full power. All of these factors add up to what is an AMAZING feat of electrical engineering.
In addition to all these factors, it is designed to be used each and every day in professional use for years. The reason that Profoto Pro packs are the #1 pack found in any major rental studio from Tokyo to NYC to Paris, etc. is they just perform, day in and day out. The modifier selection is excellent and the flash tubes last seemingly forever. For those coming to the lighting workshop, remind me to show you a Profoto Pro-B head that has almost 500,000 shots on the original tube, after being dipped, powered-on into the Atlantic ocean... twice.
So, why do you need this level of control, accuracy, and performance? You may not for your photography, but some might argue that the price of Leica, Zeiss, or Schneider glass isn't worth it. How could a 50mm lens cost $6,000, for example? Or, some may question whether they need a 60MP MFD back, or even a 31MP MFD when a Nikon or Canon would do. Why spend $40K on a digital camera when $1K will do? The reality is that the equipment is there for those who need it, whether it be lighting, lenses, or camera backs. For many studio shooters, this pack would be a better investment than a new digital back every two years, especially if you were doing multi-shot shooting for commercial product.
If you're attending the lighting workshop, you'll get to see what the fuss is about Profoto, as that is what the host studio uses 100%, from packs to soft boxes. Lots of 7a and D4 packs. The 8a won't be available yet, but you'll be able to see where the money goes. A 7a 2400 is over $9K today, so $2K more for A LOT more performance is a pretty good deal actually.
David
