Kenko Tokina Co., Ltd. Filter-type focusing tool “Kenko Night Focus 82mm” for focusing on stars

Kenko Tokina Co., Ltd.
Kenko Night Focus 82mm, a filter-type focusing tool for focusing on stars Released on December 8th at the same time as Kenko Square Conversion Frame for 82mm, which allows night focus to be used with a 100mm wide square holder.
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Kenko Tokina Co., Ltd. (Headquarters: Nakano-ku, Tokyo, President and CEO: Toru Yamanaka) will start selling the filter-type focusing tool “Night Focus 82mm” for focusing on stars from December 8, 2023. Masu. Manufacturer’s suggested retail price (excluding tax) is ¥15,500. The Kenko Square Conversion Frame for 82m, which will be released at the same time, has an open price, but is expected to have a selling price of 6,280 yen (tax included).
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Kenko Night Focus is a “filter-type focusing tool for focusing on stars.” When taking starscape photos, it is difficult and time-consuming to focus on the stars accurately.
Night Focus was developed to make this easier and ensure sharper focus. It is used by attaching it to the front of the lens like a regular screw-in filter. (Used only for focusing.)
The pattern applied to the glass surface generates three rays from a bright star, and by adjusting the focus so that the intersections of the three rays overlap, you can accurately focus on the star.

The idea for night focus is based on the Bahtinov mask, invented by Russian astronomer Paul Bahtinov. This is an astronomical telescope with a focal length of 500mm or 1000mm or more, and is used to obtain reliable focus when photographing nebulas and star clusters. Since the Bahtinov mask is used for astronomical telescopes, its optical characteristics do not match the short focal length lenses used for starscape photography, and it was not possible to obtain sufficient focusing effects.
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For Night Focus, we carefully examined the optical characteristics of the 24-70mm zoom lens that many people use today. Also, unlike the Bahtinov mask, it has high light transparency, which prevents your field of vision from becoming dark.
How the stars look when using night focus
When you look at a first-magnitude star with a night focus attached, a ray appears around the star. The star is in focus when the
intersections of the three rays overlap and appear to align with the center of the star (Figure 1).
When you move the focus ring, only the rays in the center appear to move (Figures 2 and 3). Adjust by moving the focus ring slightly. [Image 4
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Lenses and cameras that can use night focus
Target camera
Camera with live view function
Target lens
24-70mm, F2.8~4 zoom lens
20mm to 50mm, F2 to 2.8 single focal length lens
If the focal length and F number are close, you can use it. Some lenses can be used from 18mm to 75mm.
*At the design stage, the optical characteristics are matched to an F2.8 or F4 24-70mm zoom lens.
*The ease of focusing may vary depending on the lens design. *Some AF lenses that electronically transmit the movement of the focus ring may not have a precise pitch and may not be able to be adjusted to the exact position.
*It may be difficult to focus when the upper atmosphere is turbulent.

How to use
1: Attach the night focus to the lens
2: Put a bright star in the center of your field of vision
3: Maximize magnification in live view
4: Focus
5: Take a preview with night focus on
6: Play the image, enlarge it, and check the focus
7: Remove the night focus, decide on the composition, and take the actual shot

Regarding attachment to the lens
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Night focus is a screw-in type similar to a regular filter, and can be attached directly to the lens. Night focus is available in one size 82mm, so be sure to prepare a step-up ring to match the lens you have. You can also use the “Kenko Square Conversion Frame for 82mm” to use night focus in combination with a 100mm wide square filter holder. Square conversion frame is an item that allows you to attach a round filter to a square filter holder.
Other features
made in Japan
Adapter for attaching a 82mm diameter round filter to a square filter holder. Square conversion frame for 82mm
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This is an adapter for attaching an 82mm diameter round filter to a square filter holder (model compatible with 100mm width and 2mm thick filters).
A screw-in round filter can be quickly attached and removed by sliding it like a square filter, and filter work that combines a round filter and a square filter is possible.
Selling agency
Kenko Tokina Co., Ltd.
https://www.kenko-tokina.co.jp/