Adjustable Bahtinov Telescope Focusing Mask

Use a visible diffraction pattern as a telescope focusing reference with a Bahtinov mask. Select the size around your optical tube and position the adjustable mounting posts at its opening.

✅ Judge the focus setting - Diffraction spikes provide a visible reference as you adjust telescope focus.

✅ Match the tube opening - Multiple mask sizes let you select around the dimensions of your telescope tube.

✅ Position the mask for focusing - Adjustable posts hold the mask around a compatible front opening during the focusing step.

Set focus with a pattern you can compare

A Bahtinov mask creates diffraction spikes that change as the telescope focus changes. Those visible lines give you a reference to compare while you bring the focus setting into position.

Measure the optical tube dimensions when selecting a size, rather than relying only on the stated aperture. Fit the mask for the focusing task and remove it before normal observation or imaging.

Technical details

• Adjustable mounting posts
• Several size options; select by actual tube dimensions
• Main image shows one size option
• Remove after focusing
• Not a solar filter

Measure your telescope tube and select a focusing mask that fits.