In this series, we unravel the story behind the development of the ultra-high capability digital compact camera, the Powershot G3 X. This second instalment centres on the camera’s lens. How did the developers manage to fit a lens with a 25x zoom range on a body powered by a large 1.0-inch type sensor? We ask Mr. Hiroshi Saruwatari, who was in charge of lens development.
Pages: 1 2
ICP Development Center 1
"The ultimate lens created with Canon’s vast amount of data and know-how accumulated through the development results of an abundance of lenses."
A high point of Canon’s comprehensive optic strength
- How were the specs for a 24-600mm, 25x zoom determined?
Saruwatari Making the overall optics as compact as possible at maximum telephoto which would normally be very long was the design policy of the PowerShot G3 X lens. As increasing the size of the sensor and making the zoom a higher magnification would cause the overall optics to lengthen, this was an extremely difficult challenge. However, as there are few high-power premium models on the market, this was an initial attempt for Canon. As the project progressed, even amongst the development team we put ourselves in the user's position and said things like, "This magnification is just not enough," or "Nowadays I'd really like to have a 24mm wide angle," and became more and more excited. In the midst of our efforts to create something that is the world's first, and best that would have an impact on the market, we were able to achieve a 24-600mm, 25x zoom lens. Without a doubt, concentrating Canon's technical capabilities led to this ultimate magnification at the present point in time. I believe that we have something to offer users that can be used for a long time to come.
The lens of the PowerShot G3 X was developed making full use of the know-how from EF lens production. Its optical design, where 18 lens components are divided into 6 lens groups that combine positive and negative lens elements 3 times, enables the realization of a 25x high zoom within the compact lens size.
- What was the reason for realizing the current construction?
Saruwatari By utilizing a six lens group construction, the lens‘s positive and negative are combined three times for a first in Canon's compact camera optical design, successfully shortening the overall length of the lens. Rather than a compact camera construction, you could say that this is more like the design style of an interchangeable lens. We were able to optimize by holding hearings with designers in the same department regarding characteristics of comparatively similarly designed EF telephoto zoom lenses, and implemented this feedback about the design into the PowerShot G3 X. In order to attempt the development of a highly innovative lens in a high-power model equipped with a 1.0-inch type sensor, having access to the extensive knowledge and numerical data obtained through an abundance of past product development is a major strength of Canon.
- What countermeasures were made for aberration?
Saruwatari As the focal length increases, aberration also inevitably increases. In order to suppress this aberration, UD lenses and aspherical lenses were used without hesitation, reducing aberration fluctuations throughout the full zoom range. In addition, this correction also makes use of knowledge obtained from EF telephoto zoom lenses. With a high-power model, accurately understanding aberration fluctuations that accompany zoom and focus is important, so by utilizing data of telephoto zoom lenses with results up until now that have comparatively similar characteristics to the PowerShot G3 X, I believe that this made it possible to offer a product with even greater stability and reliable image quality to the users.
By freely utilizing UD lenses, aberration is suppressed throughout the full zoom range.
Achieving a high level of image stabilizer performance
Easy shooting is possible even when handheld, achieving a high level of image stabilizer performance.
- What countermeasures were made camera shake?
Saruwatari With existing high-power models, lens group three performs image stabilization, however, with the PowerShot G3 X, image stabilization using lens group two is implemented for the first time on a Canon compact camera, achieving even more powerful IS. In addition, using lens group two for IS has merits for image quality as well. Optical IS moves the lens perpendicularly to the optical axis, so if it cannot be controlled accurately, there is a risk that aberration and peripheral illumination loss due to deviation, etc. can deteriorate image quality. However, as lens group two that is even closer to the subject can capture light from an even wider angle, it can suppress the risk of peripheral illumination loss. As the controlling lens is large and heavy, being difficult to implement on compact cameras that have restrictions for the electric power and motor size which was a problem, however, this was overcome in cooperation with the lens barrel department, achieving both high IS performance and beautiful image quality. With high-power shooting, there are probably many situations where you can attach the camera to a tripod and take time to shoot, however, I believe that performance was achieved that makes easy handheld shooting possible.
Unlike previous high zoom compact cameras, the second lens group in the PowerShot G3 X is equipped with an image stabilizing mechanism. This not only ensures more powerful image stabilization, it also lowers the risk of peripheral illumination loss, resulting in even better image quality.
- What problems were encountering during manufacturing?
Saruwatari As the design was extremely difficult, the level of precision for production tolerance and parts was extremely high. In order to achieve precise lens placement, interaction overlapped from the prototype stage with cooperation between the lens barrel department and Nagasaki Canon which carries out production. As a result of repeatedly improving the parts precision and assembly precision down to the micron, it was possible to achieve even stricter precision than the values we had permitted at the initial design stage.
When it comes to producing a groundbreaking high-power premium compact camera, I believe that by design and production departments working together, it was possible to instill enthusiasm.
By cherry-picking the best parts of compact cameras and interchangeable lenses, virtually all normal shooting demands are met with one camera.
- How would you like to see this camera used?
Saruwatari As this many focal lengths are maintained, I think that it can handle virtually all normal shooting demands. In terms of the maximum telephoto of 600mm in particular, interchangeable lenses are large sized, and extremely expensive. The reasonable price, and being able to carry around a compact body are major points of appeal. On the other hand, as 24mm is also being maintained at maximum wide-angle, it also has the combined feature of a compact camera’s wide-angle lens. Quite simply, I think with this camera we have “cherry-picked” from compact cameras and interchangeable lenses. I would like people to be comfortable using it in a variety of scenes from athletic meets to photographing one's hobbies.