Adjustable Bahtinov Telescope Focusing Mask

Use a Bahtinov diffraction pattern to judge telescope focus, with adjustable mask sizes for different optical tubes.

Set telescope focus with a visible reference

• ✅ See a focus reference – The mask creates diffraction spikes that help you judge the focus setting.
• ✅ Choose the tube fit – Multiple size options let you match the mask to your telescope.
• ✅ Position it at the front – Adjustable mounting posts hold the mask around a compatible tube opening.

Select a size using the telescope tube dimensions, not only its stated aperture. The main image illustrates one size option.

Fit the mask for focusing, then remove it before normal observation or imaging. It is not a solar filter.

Measure your telescope tube and choose a matching mask. Explore more optics accessories.