Canon Patent: RF 18-35mm f/1.8 DS & RF 120-300mm f/2.8 DS (Defocus Smoothing)

Defocus Smoothing
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And here is another Canon patent application for two RF-mount lenses with Defocus Smoothing technology.

Canon patent application 2022175307 (Japan, published 11/25/2022) discusses optical formulas for two RF-mount lenses with Defocus Smoothing technology, RF 18-35mm f/1.8 DS & RF 120-300mm f/2.8 DS. No surprise Canon is porting this technology to the RF-mount. From the patent literature:

To provide a variable power optical system that obtains a good apodization effect over the entire zoom range and that has a small change in T number with variable power.

Description of the Related Art

Conventionally, in order to obtain an appropriate blurred image, there has been known an optical system equipped with a filter whose transmittance distribution changes, such as an apodization filter whose transmittance decreases as the distance from the optical axis increases. ing. Patent Literature 1 discloses an optical system in which apodization filters are arranged before and after the aperture of a single-focus lens.

However, since the optical system disclosed in Patent Document 1 is a single focus optical system, it is insufficient as a method for obtaining a sufficient apodization effect in each zoom state of the variable magnification optical system. In addition, as a specific requirement of a variable-magnification optical system, it is required that the change in brightness, that is, the T-number, is small when the magnification is varied, especially in video shooting.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a variable magnification optical system and an optical apparatus which have a good apodization effect over the entire zoom range and have a small change in T-number due to variable magnification.

Example 1

  • Focal length: 18.60-33.78
  • F-value: 1.80-1.86
  • Half angle of view: 37.69-23.05
  • Image height: 14.37
  • Overall length: 168.50
  • Back focus: 38.56-39.91

Example 2

  • Focal length: 18.50-34.00
  • F-value: 1.75-1.86
  • Half angle of view: 37.99-23.03
  • Image height: 14.45
  • Total length: 163.25-166.00
  • Back focus: 38.56-41.75

Example 3

  • Focal length: 37.00-68.00
  • F-value: 1.65-1.86
  • Half angle of view: 25.94-14.83
  • Image height: 18.00
  • Total length: 326.49-332.00
  • Back focus: 77.12-83.49

Example 4

  • Focal length: 51.50-97.00
  • F-value: 1.87
  • Half angle of view: 15.59-8.43
  • Image height: 14.37
  • Total length: 204.13-204.12
  • Back focus: 48.80-48.79

Example 5

  • Focal length: 123.60-290.82
  • F-value: 2.89
  • Half angle of view: 9.93-4.25
  • Image height: 21.64
  • Total length: 433.07-433.08
  • Back focus: 54.98-55.00

Sigma 120-300mm f/2.8 DG OS HSM Lens In Stock And Ready To Ship (and review)

Sigma 120-300mm f/2.8

The image stabilized Sigma 120-300mm f/2.8 DG OS HSM is in stock at B&H for $3,599 (click here). The lens gets good reviews, for instance at ephotozine were they write:

Although the performance of this lens isn’t of the same absolute brilliance of the Nikon and Canon fixed super-telephoto lenses, it isn’t all that far behind. Add in the flexibility afforded by the zoom and it still makes a compelling alternative to the camera manufacturer’s own fast telephoto glass.

They point out the good sharpness, low chromatic aberration, high build quality, fast AF. Excellent value for the money.

[Photokina] Contemporary, Art and Sports: Three New Sigma Lenses For Your Photographic Needs

Sigma announced three new lenses at Photokina, the Sigma 17-70mm f/2.8-4 DC MACRO OS HSM, Sigma 35mm f/1.4 DG HSM and the Sigma 120-300mm f/2.8 DG OS HSM. These lenses aim at three different “photographic categories”: Contemporary, Art and Sport.

Sigma 17-70mm f/2.8-4 DC MACRO OS HSM (contemporary)


Mainly used for general-purpose photography, this everyday lens covers a range equivalent to 25.5-105mm on a 35mm camera. A large-aperture lens that opens up to F2.8, it’s surprisingly compact in size. Great for treasured snapshots of travel or family occasions, it also handles shots that are a little bit more creative. Designed to be the kind of lens you carry around with you all the time, it delivers simplicity and is so user-friendly it’s sure to satisfy even the most demanding of users.

Sigma 35mm f/1.4 DG HSM (art)


Photobucket Pictures, Images and Photos

Many avid photographers will definitely prefer this 35mm lens to the more conventional 50mm. Using a leading-edge design and state-of-the-art production technology, we’ve honed its performance to the point where it can do full justice to the expressive power of the very latest digital cameras. At low apertures, for example, it can perform like a wide-angle lens, while if it’s opened up to F1.4, it will give the background a pleasing bokeh effect and make the subject pop like a mid-range telephoto lens. What makes this lens so desirable is the wide scope it provides for artistic expression.

Sigma 120-300mm f/2.8 DG OS HSM (sport)

Although high-function digital cameras now deliver improved picture quality at high-ISO settings, adjusting your lens to a large aperture is still the most effective strategy for action shots. And even if you have to take the shots from a less-than-ideal position, as is so often the case when shooting sports or on-stage action, this zoom lens, with its maximum focal length of 300mm, lets you open up the aperture all the way to F2.8. In other words, when conditions are difficult, this high-performance lens gives you more scope to express yourself in the shots you take.