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Bahtinov Mask for 18-55mm Lenses

Free Bahtinov Mask for 18-55mm Lenses 2023-10-06

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This is a 3D printable Bahtinov Mask to assist with manually focusing on the night sky. Bahtinov masks work by creating diffraction spikes from a point light source (like a star) spread out across different sections of the lens. When the point is out of focus, the diffraction spikes land on different parts of the sensor, so changing the focus moves the spikes relative to each other. The angled diffraction spikes move together because they are on the same side of the lens, forming an “X” shape that stays together. The horizontal diffraction spike moves to the left or right relative to the “X” depending on the focus, giving feedback to the user on which direction they need to adjust the focus. When the point light source is in perfect focus, the central diffraction spike will be in the center of the “X” pattern, and the Bahtinov mask can be removed to take pictures with the stars in focus.

The diffraction spikes are more visible at higher focal lengths, but I designed this around still being able to be used at lower focal lengths with bright objects. It becomes more useful with dimmer objects at higher focal lengths.

This Bahtinov mask has a nominal gap size of 0.45mm for the central spike, and 0.39mm for the angled spikes.
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