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Multi-Power Battery Pack MB-D10

The flagship model in Nikon's DX format range, the D300 digital single lens reflex camera, was launched in November of 2007. The Multi-Power Battery Pack MB-D10 is a device that unobtrusively facilitates this camera's outstanding portability. This revolutionary battery pack combines sleek design, functionality, and usability. We discussed its appeal with the people in charge of its design, mechanics and electronics.

Tsuyoshi Watanabe
Deputy Chief of the Third Design Department, First Design division, Nikon Imaging Company Development Headquarters
PROFILE:
Responsible for camera body design since joining the company in 1993. Participated in the design of all kinds of single lens reflex cameras dating back to the era of film cameras and running the gamut from entry level models to the F100, the D200, and most recently the D300. For almost 30 years he has pursued his hobby of photographing the night sky.
Michiyo Ogasawara
Designer, Product Design Department, Design division, Nikon Imaging Company
PROFILE:
Joined the company in 2005. Worked chiefly on the design of the MB-D10, but was also responsible for the D300. Worked previously as a designer of household appliances and an instructor in 3D CAD, and is now making full and active use of that experience. Her hobbies are traveling and watching movies.
Kiyoshi Yasuda
Deputy Chief of the First Design Department, First Design division, Nikon Imaging Company Development Headquarters
PROFILE:
Entered the company in 2006 and immediately joined the overall design effort for the D300, including design of the battery pack. Uses his extensive knowledge primarily in overseeing electronics systems. His hobby is watching movies.

The appeal of a new battery pack that gives the camera added power

Could you first outline the MB-D10 for us, please? How does it differ from its predecessor, the MB-D200, and what are its sales features?

Besides AA, EN-EL3e and EN-EL4a
batteries can also be used.

Watanabe:

The MB-D200 takes two types of batteries-AA or EN-EL3e. The new MB-D10 takes these two types, as well as the EN-EL4a and EN-EL4 [collectively referred to below as EN-EL4a]. The principal change is that the camera's functionality has been improved as a result of the higher voltage achieved through the use of these batteries. If an EN-EL4a battery or AA batteries are used, the frame speed increases from 6 frames per second to 8 frames per second. The image go-out time is also shortened from 90ms to 86ms. An additional feature is that the battery pack can still be used even when there is still a battery inside the camera. The battery in the camera and the battery or batteries in the battery pack work in tandem, and the camera can switch between the two power sources successively. This power source switching was a considerable challenge for Mr Yasuda, who was in charge of electronics. These were the three major changes in specification.

Were there any new approaches adopted in the electronic systems too?

Mr Yasuda talks about the new
challenges in electronics.

Yasuda:

Special capacitors are used to boost the peak current. Specifically, since the camera battery simultaneously provides both the power for driving the mechanical system and the power for computer control, when a photograph is taken, a large current flows for an instant-this is the so called peak load point. At that point it is the capacitors that help to provide a stable power supply with no drop in voltage. The special lithium battery achieves the same effect of preventing a voltage drop, but with AA batteries there is a considerable drop in voltage. The built in capacitors compensate for this. Since the MB-D200 only used AA alkaline batteries as an emergency back up, the number of photographs that could be taken was nothing to shout about. With the MB-D10, however, we are now able to offer a more practicable specification.

Watanabe:

We received numerous requests from users regarding battery life. In simple terms, the capacitors enable the full capacity of the battery to be used, right to the very last drop. With existing cameras, before the battery is completely drained, the camera automatically judges that the battery has been used up and it becomes impossible to depress the shutter. With the D300, however, the camera can be used until the battery capacity has been completely exhausted.

Searching for something better, with design requirements from a woman's perspective

The MB-D10 appears to be curvier than the MB-D200. In design terms, what was the thinking while the device was being developed?

Ogasawara:

The main objective was to make the best use of the design characteristics of the D300, since the battery pack is auxiliary to the camera. The camera features lots of intricate curves and great care was devoted to making it easy to carry. Thus, our design concern was that, with the battery pack attached, it should be comfortable to handle and grip the camera, irrespective of whether it is being held horizontally or vertically. We believe that it has a much more vibrant and ergonomically polished design than the MB-D200.

At a more detailed level, how did the development process proceed? You worked previously as a 3D CAD instructor. Was this experience a big help to you?

Ogasawara:

First we made clay prototypes in the workshop. We made models using clay that we could actually touch and try out as we went along, and that were easy to grip, even for a woman like me. Finally, we produced a CAD representation of the device, and this seemed to enable us-despite the short development period-to turn our formless concept into a 3D form that clearly conveyed our intentions to the designers.

In a magazine interview you said that for the first two years after joining the company, you didn't think that you would survive there. What did you mean by that?

Ms Ogasawara explains the design points she adhered to in her first camera job.

Ogasawara:

Although I possessed manufacturing skills from having worked as a CAD operator, I felt as if-how can I put it?-I had strayed into a different dimension. It seemed as if everyone was on the cutting edge, and it was a struggle simply to properly understand the technical terminology that they were using and the things that they were saying.
There were also design demands from various quarters during actual production (laughs). Since this device was to be used as an attachment to the D300, it would have been tempting to think only of producing clean lines that matched the camera itself. However, we were also aiming to make use of the standard battery holder used on the F6 camera, in order to allow an EN-EL4a to be used, and I had a hard time getting the shape of the battery pack to conform.

Watanabe:

Our first thought was to produce a device that would enable customers with an F6 battery pack to use their existing battery holder. Thus, we requested a design which could use the F6's BL-3 battery holder and which would match the D300.

It's clear from the completed device that the design and the mechanics have been harmonized with one another. Were there any other particular challenges in working with one another on development?

Watanabe:

We attached a multi selector, which is necessary for when the camera is used in the vertical position. On the D200 there were only 11 autofocus points, but since this has jumped to 51 autofocus points on the D300, the conventional selector method combining a AF-ON button and a command dial was no longer practicable. In short, from the outset we were confronted with the problem of having to attach a multi selector to the battery pack for use in the vertical position. However, this was very hard-both from the design and mechanical viewpoint.

Ogasawara:

The AF-ON button is also in a completely different position compared to previous devices. This was due to the design department's intention to make it match the positions of the camera's buttons as far as possible. The dial section's gentle curvature is intended to maximize the operability of the camera. Naturally, the battery pack must also be curved so that it matches the camera. This was a major design requirement. Working this curvature into the design must also have been extremely difficult for Mr Watanabe; however, he rose to the challenge.