TS Optics Bahtinov Focusing Mask 85-120 mm
Sharp focus is the foundation of every astrophotography image. The TS Optics Bahtinov mask is a plastic focusing aid that fits over the front of a telescope or camera lens. It lets you achieve the exact focal plane with complete confidence. This mask is designed for telescopes and camera lenses with an outer diameter of 85 to 120 mm. Its simple design and quick attachment make it an essential tool for any night of deep sky or planetary imaging.
How the Bahtinov mask works
The mask is named after its inventor, Pavel Bahtinov, who developed this elegant optical principle for unambiguous focus confirmation. Instead of guessing sharpness on a live view screen, the Bahtinov mask shows you a diffraction pattern of three lines. When the central line aligns precisely with the two outer lines, focus is correct. The result is immediately visible and requires no experience or special software. Simply adjust the focuser, watch the diffraction pattern, and stop when the lines meet at a single point.
Quick and secure attachment
Fitting the mask takes less than a minute. Each mask comes with three screws and plastic caps. Remove the caps, feed the screws through the corresponding holes, and replace the caps. The prepared mask then clips securely onto the telescope tube or lens barrel and holds firmly throughout the focusing process. Once you reach the correct focus, remove the mask and start your exposure straight away.
Step-by-step focusing guide
The focusing process with a Bahtinov mask is straightforward and reliable:
- Fit the mask onto the telescope and point it at a bright star near your target area.
- Switch on your camera, activate live view, and observe the diffraction pattern of the chosen star.
- If focus is off, the central line will be visibly shifted relative to the two outer lines.
- Adjust the focuser until all three lines merge into a single point.
- At that moment, you have achieved optimal focus for astrophotography. Remove the mask and begin imaging.
Key specifications
| Parameter |
Value |
| Compatible outer diameter |
85-120 mm |
| Material |
Plastic |
| Attachment method |
Three screws with plastic caps |
| Suitable for |
Telescopes and camera lenses |
| Use case |
Astrophotography - deep sky and planetary |
Who is this mask for?
The TS Optics Bahtinov mask suits anyone who photographs the night sky - from beginners taking their first deep sky images to experienced imagers who value a fast, reliable focusing routine. If you use a telescope or camera lens with an outer diameter between 85 and 120 mm, this mask will save you time and improve the sharpness of every shot.
