Optical Designer Interview - RF Lens World - Canon India

For example, when you want to make a bigger image of a small flower, you step forward to get closer, right? However, most common lenses don’t focus well even if you move closer to get a bigger picture. Furthermore, even if the camera is in focus, the closer you get, the worse the image quality becomes normally. Macro lenses are designed to solve such problems by providing good focus even when you are close to the subject.

The macro lens design is similar to the zoom lens design. The macro lens moves each lens in a large way like a zoom lens to increase the shooting magnification. But unlike the zooming move by manually, autofocus, which requires speed and precision, requires special design. Therefore, macro lenses that support autofocus are designed with a lot of technology to achieve quickness and accuracy, including not only the weight and trajectory of the moving lens but also how to hold and control the lens.

We aimed for 1.4 for this lens to enable confident macro photography and a wider expression. In case of a 1.0x magnification lens, it is easy to lose focus if the subject comes even slightly closer from the position. However, by using a macro lens that can shoot up to 1.4 magnification, there is more room in the shooting distance, and even if the subject suddenly gets close, it will be in focus and you will be able to take pictures with confidence. Furthermore, when shot at equal or higher magnification, it can depict a beautiful world that is completely different from what your eyes see. I would like you to experience the beautiful macro world through this lens.

The large aperture and short back focus enabled maximizing the range of motion of the focus lens. The optics of a typical macro lens have been refined over time, and focus type, IS type and aperture position are fixed to some extent. However, it was essential to break away from the existing types in order to achieve a 1.4 this time. Unlike conventional macro lenses, this lens achieves 1.4 by placing the IS or aperture in the front, separating it from the focus, and moving the focus lens to the very edge of the mount.

First of all, it's important to always think from the ground up and not get caught up in common sense. I think it will be difficult to break away from existing types and create new value in any field. In fact, the design of this macro lens started with a single convex lens, rather than a design based on existing lenses, which led us to this arrangement. If you compare the cross section of this lens to other macro lenses, you may see that it has a completely different configuration.

Special lenses are usually used to reduce the occurrence of aberrations, but this lens does not use that special lens to reduce aberrations. This was made possible by the use of a concave lens in the foreground, which gently accepts light rays from close subjects and gradually bends the light to reduce the occurrence of spherical aberration. Then I added a convex lens and corrected chromatic aberration.

As the shooting magnification increases, the range of focus becomes very narrow, and the blurred range increases, allowing for more mystical depictions. However, a slight camera shake can cause the camera to go out of focus, making it difficult to focus on the area you want to focus on. Also, the fact that the subject appears larger means that camera shake has a greater impact than usual. So, when you’re shooting at 1.4, you need precise autofocus and powerful image stabilization.

We designed the aberration variation to be smaller when the image stabilization lens is moved. In addition, it cooperates with the camera's in-body image stabilization for even more powerful image stabilization.

In order to achieve 1.4 magnification, we had to move multiple lenses widely. This lens is equipped with a Canon proprietary ultrasonic motor called “Nano USM” which achieves high-speed, high-precision autofocus.

We designed it to achieve high image quality not only in macro photography, but also in all shooting areas, including landscapes and portraits.

This macro lens is equipped with Nano USM, so you can enjoy comfortable video shooting with quiet and quick autofocus. In addition, when shooting video, you might be concerned about focus breathing, which is the angle of view change during focus. By adopting a new focus type for this lens, the focus breathing is mitigated.

The idea to control the spherical aberration called “SA” was inspired by the fact that the Nano USM can freely change the focus trajectory. By precisely controlling the aberration, which only made the image quality worse, we were able to increase the freedom of expression, such as softening the bokeh or making it harder.

I’m shooting small shrimp and killifish. In fact, recently I started to have a water tank at home after my child got a killifish. The aquarium construction is enjoyable for adults, and the number has increased to four, but small fish and shrimp are swimming around actively. With this lens, you can comfortably take hand-held pictures of fish in action. I found this lens to be really good, less shaking, fast to focus, and 1.4 magnification is fantastic. I hope you also enjoy macro photography with this lens.