Canon patent application 2024007656 (Japan, published 19/01/2024) discusses optical formulas for two wide angle zoom lenses.
10-20mm f/4 with internal zoom mechanism
From the patent literature:
An object of the present invention is to provide a zoom lens that has high optical performance, is compact, and has a wide angle of view.
BACKGROUND ART Wide-angle lenses are widely used for landscape photography, astronomical photography, and the like. Wide-angle lenses are required to have high optical performance and realize a wide angle of view while being compact.
Generally, in a negative read optical system, the constituent lens groups are arranged asymmetrically, making it difficult to correct various aberrations such as astigmatism. In particular, when widening the angle of view or downsizing the lens, the refractive power of the lens group closest to the object, which has a negative refractive power, becomes stronger, so that many of the above-mentioned aberrations occur.
For this reason, in order to achieve a wide angle of view and miniaturization in a negative lead type optical system, and to properly correct various aberrations such as curvature of field and obtain high optical performance, the refractive power of each lens group must be adjusted. It is important to set these appropriately.
In Patent Document 1, various aberrations such as astigmatism and field curvature are corrected by weakening the refractive power of each lens group, but this increases the size of the optical system, which is undesirable.
Accordingly, an object of the present invention is to provide a zoom lens that has high optical performance, is small in size, and has a wide angle of view.
Canon Introduces Three New Lenses, Enhancing Still Photography and Video Production for Any Skill Level
MELVILLE, NY, November 2, 2023 – Photographers aiming to get a powerful, ultra-wide angle shot, or looking for a superb zoom range, can improve their images with three new lenses announced today by Canon U.S.A., Inc., a leader in digital imaging solutions. The RF-S10-18mm F4.5-6.3 IS STM, the RF24-105mm F2.8 L IS USM Z, and the RF200-800mm F6.3-9 IS USM lenses can benefit a wide range of users — from beginners all the way to working professionals.
The RF-S10-18mm F4.5-6.3 IS STM lens offers users of APS-C sensor size EOS R-series cameras an ultra wide-angle zoom, helping create strong still images and video. It is an ideal lens for vloggers, travelers, and general shooters. Beginners in video and still photography can make good use of this lens, as well as the more advanced pros. Key features include:
10–18mm ultra-wide zoom (equivalent to 16-29mm on full-frame camera).
Image Stabilization, for even greater hand-held sharpness and video steadiness.
Compact and lightweight design, making it an excellent choice for travel.
A new optical design, optimized for RF lens mount and APS-C sensor size.
An affordable price tag for those just stepping into ultra-wide video and still imaging.
Still and video professionals who want a single lens that can handle most tasks with low-light capabilities will find what they’re looking for with the RF24-105mm F2.8 L IS USM Z. This is the world’s first 24-105mm focal length lens combined with consistent f/2.8 maximum aperture,1 offering true portrait-length telephoto coverage resulting in sharp images. High-end photographers, photojournalists, and video content creators can utilize this lens’ other features that include:
Constant overall length when zooming.
Manual aperture ring for video use.
Optimized optics for high-level video.
A new Power Zoom Adapter will also be available for the RF24-105mm F2.8 L IS USM Z lens, an optional accessory for super-smooth zooming during video operation. This detachable device allows for more natural movement when zooming in and out, and easier control for solo camera operators. A standard version of the Power Zoom Adapter will be available, as well as a 20-pin port version to support zoom and focus demands. The firmware updates that will be available in early December for the EOS C70 and EOS R5 C cameras will add support for the RF24-105mm F2.8 L IS USM Z lens. For more information on the new firmware updates, please visit here .
Last, but not least — nature, wildlife, and outdoor sports shooters will find the RF200-800mm F6.3-9 IS USM super telephoto zoom lens a great tool to take crystal-clear images of action at a distance. This lens is lightweight and easy to hold in your hand, allowing most users to carry it to help capture a range of subjects, whether it’s a still image of a landscape, or video of a moving target. Unique features of the RF200-800mm F6.3-9 IS USM lens also include:
Up to 800mm focal length.
Up to 5.5 stops image stabilization.
Compatible with optional Canon RF 1.4x and 2x tele extenders.
Rotating tripod mount.
Price & Availability
The RF-S10-18mm F4.5-6.3 IS STM, the RF24-105mm F2.8 L IS USM Z, and the RF200-800mm F6.3-9 IS USM lenses are expected to be available in December for estimated retail prices of $329.99, $2,999.00, and $1,899.00, respectively2. The two versions of the Power Zoom Adapter for the RF24-105mm F2.8 L IS USM Z will be available Spring 2024 for an estimated retail price of $999.99, and $1,299.002 for the version with the 20-pin port. For more information, please visit usa.canon.com.
B&H Photo has the Canon EF-S 10-18mm f/4.5-5.6 IS STM lens on sale at $199. Compare at $299. Free shipping. Although being an inexpensive lens, the Canon EF-S 10-18mm f/4.5-5.6 IS STM got plenty of positive reviews.
The EF-S 10-18mm f/4.5-5.6 IS STM means one thing first and foremost: a lot of bang for the bucks. Here comes another review, by Photography Blog.
Excerpts from the conclusion:
The in-expensive Canon EF-S 10-18mm f/4.5-5.6 IS STM offers more features and much better image quality that you might expect given its price-point, making it a great ultra-wide-angle addition to a compact, lightweight EOS kit
[…] capable image stabilisation system makes it easier to hand-hold the camera and still get the shot. Auto-focusing is surprisingly quick, and for video shooters the STM motor is appealingly smooth and almost completely quiet, although not fast enough to keep up with fast-moving subjects in Live View/Video mode.
[…[ In summary we can somewhat surprisingly recommend the Canon EF-S 10-18mm f/4.5-5.6 IS STM as a lightweight, portable ultra-wide-angle zoom lens for APS-C DSLR owners that delivers pleasing results for both stills and video