Canon Patent Application: Canon RF Super telephotos

In this patent application, another series of super telephotos appear, as with times in the past this one again deals with reducing chromatic aberrations when attempting to reduce the weight of the lens.  However, there is one important difference.  After looking again at this patent application, I realize that these lenses are for the RF mount and not for the EF mount.

EF mount super telephotos have the back focus distance between 60-75mm well exceeding the distance between the sensor and the lens mount of 44mm for the EF mount.

The backfocus distances shown here are well under the 44mm required for the EF mount, therefore these are super telephoto designs specific for the RF mount which has a focal plane distance of 20mm.

From the patent application;

In an ultra-telephoto lens, generally, the longer the focal length, the more axial chromatic aberration or magnification chromatic aberration occurs. As a technique for excellently correcting these types of chromatic aberration, a technique for increasing the number of lenses placed on an object side and causing the lenses to share the action of correcting chromatic aberration is known. However, the effective diameter of a lens placed on the object side of the ultra-telephoto lens is likely to be large. Thus, if an attempt is made to correct chromatic aberration by the above technique, the weight of an imaging optical system increases. 

The embodiments shown in this patent application are;

Focal length 392.00
F-number 2.90
Angle of view 3.16
Image height 21.64
Entire lens length 360.03 
BF 31.01 

Focal length 490.00
F-number 4.12
Angle of view 2.53
Image height 21.64
Entire lens length 412.08 
BF 33.39

Focal length 588.00
F-number 4.12
Angle of view 2.11
Image height 21.64
Entire lens length 476.08 
BF 33.21

While some of the patent applications will never make it into final lenses, or cameras, patents like this most likely will, but we'll never know it. This one seems more likely to come out for the RF mount, because from what I've seen, this is the first sign of an RF mount supertelephoto specific patent application. The vast amount of super telephoto patents that never seem to stop coming, really do show why these lenses are expensive.  The research and development of the lenses never stops.

US Patent Application 20190155003