Lens design of XF90mmF2 R LM WR
Since the announcement of XF90mmF2 R LM WR, there is quite a buzz about the lens. By looking at the spec, MTF chart and the sample images, people are surprised on the ultra sharp images that sharpness of the lens produces. Today we would like to talk a little bit on what we carefully considered upon designing and developing the lens.
When designing telephoto lens, color aberration often becomes the problem.
In order to create a sharp telephoto lens, the color aberration problem needs to be taken care of. Let’s take a look at the lens construction of the XF90mm. You can see that 3 ED glass lenses are utilized.
Generally speaking, only 2 ED glass lenses are utilized for a lens with 135mm angle of view. So there is one extra added to the XF90mm. In addition, the unique characteristics of the lens is that 2 of them are large diameter lenses, and are used at the front end of the lens construction. This effectively works against the color aberration and therefore creates very sharp images.
The lens is designed with portrait photography in mind, so that high resolution can be achieved at short shooting distance of 1 – 3m.
MTF chart is often based on the value shot at infinity. You can see that XF90mm’s chart is already a good one. But keep in mind that the real power of XF90mm is not when the shot is taken at infinity.
Bust shot at 3m and head shot at 1m. The optimal portrait shooting distance is the reason to use the XF90mmF2 R LM WR.