Bahtinov Mask for Camera Lenses & Telescopes | Johannes Scientific
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$29.99
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Never worry about blurry stars again. Get perfect focus for astrophotography every time with a bahtinov focus tool.
Specifications
- Type: Bahtinov mask (focus tool), clip-on exterior mount
- Material: Lightweight aluminum alloy frame with soft protective tips
- Compatible with: DSLR/mirrorless camera lenses and telescopes (refractors, guide scopes)
- Mounting: Clips to the outside of the lens or dew shield, no thread engagement, removal does not disturb focus ring
| Variant | Exterior Diameter | Price |
| Small | 60-90 mm | $29.99 |
| Medium | 80-120 mm | $34.99 |
| Large | 100-160 mm | $39.99 |
If you've ever spent hours trying to manually focus your camera on the stars at night, you know the struggle. A bahtinov focus tool will cut your setup time down to mere minutes with ease.
The simplest, easiest to use Bahtinov Focus Tool for camera lenses.
Unlike screw-on Bahtinov masks that require a specific filter-thread size, this mask clips onto the outside of your lens, telescope tube, or dew shield. Simply measure the exterior diameter where the mask will attach and choose the appropriate size.
Clips to the Exterior of the Lens
The tool clips to the exterior of the lens, allowing for easy mounting and dismounting, even in the dark. Removing the mask won't bump your focus ring.
Why choose a clip-on mask?
No filter thread required. This Bahtinov mask clips around the outside of your lens, telescope tube, or dew shield. You don't need to match your lens's filter-thread size or permanently attach anything to a filter. Measure the exterior diameter and choose the appropriate size.
Three sizes are available for exterior diameters from 60 to 160 mm. Measure the outside diameter of your lens barrel, telescope tube, or dew shield before ordering.
What Size to Order
| Lens or Telescope | Diameter | Bahtinov Size |
| Canon EF-S 18-135mm f/3.5-5.6 IS USM | 77.4mm | Small |
| Nikon AF-P DX 18-55mm f/3.5-5.6G VR | 64.5mm | Small |
| Sony FE 28-70mm F3.5-5.6 OSS | 72.5mm | Small |
| Nikon NIKKOR Z 24-70mm f/4 S | 77.5mm | Small |
| Canon RF 24-105mm F4-7.1 IS STM | 76.6mm | Small |
| Fujifilm XF18-55mmF2.8-4 R LM OIS | 65.0mm | Small |
| Sigma 18-300mm F3.5-6.3 DC Macro OS HSM | 79mm | Small |
| Tamron 18-400mm Di II VC HLD (B028) | 79mm | Small |
| Canon EF 24-105mm f/4L IS II USM | 83.5mm | Small |
| Sony E 18-135mm F3.5-5.6 OSS | 67.2mm | Small |
| Rokinon/Samyang 14mm F2.8 ED AS IF UMC | 87mm | Small |
| Sigma 14mm F1.4 DG DN Art | 101.4mm | Medium |
| Sony FE 14mm F1.8 GM | 83mm | Small |
| Sigma 16mm F1.4 DC DN | 72.2mm | Small |
| Nikon NIKKOR Z 20mm f/1.8 S | 84.5mm | Small |
| Explore Scientific ED80 APO Triplet (80mm) | Tube 91mm / Dew shield 128mm | Medium |
| Explore Scientific ED80 FCD100 APO (80mm) | Tube 91mm / Dew shield 124mm | Medium |
| Explore Scientific ED102 APO Triplet (102mm) | Tube 103mm / Dew shield 155mm | Medium |
| Explore Scientific ED102 FCD100 Carbon Fiber (102mm) | Tube 120mm / Dew shield 147mm | Medium |
| Explore Scientific AR102 Achromat Doublet (102mm) | Tube 104mm / Dew shield 164mm | Large |
| Explore Scientific 115mm FPL-53 APO Triplet | Tube 121mm / Dew shield 147mm | Large |
| Explore Scientific ED127 APO Triplet (127mm) | Tube 131mm / Dew shield 177mm | Large *Dew Shield out of range |
| Explore Scientific ED127 FCD100 Carbon Fiber (127mm) | Tube 146mm / Dew shield 178mm | Large *Dew Shield out of range |
| Explore Scientific 140mm FPL-53 APO Triplet | Tube 145mm / Dew shield 178mm | Large *Dew Shield out of range |
| Explore Scientific AR152 Achromat Doublet (152mm) | Tube 158mm / Dew shield 207mm | Large *Dew Shield out of range |
Important: The size recommendations above indicate physical fit, not guaranteed focusing performance. Very wide or fast lenses may physically fit the mask but can produce diffraction spikes that are difficult to see in live view.
Frequently Asked Questions
What size Bahtinov mask do I need?
Measure the exterior diameter where the mask will actually clip onto your equipment. For camera lenses, measure the outside of the lens barrel. For telescopes, measure the outside diameter of the tube or dew shield at the point where you will attach the mask. Do not measure the front glass or optical diameter. The mask must clip securely onto a section between 60 and 160mm in outside diameter.Does it work with telescopes as well as camera lenses?
Yes. It clips to the exterior of the lens, dew shield, or telescope tube the same way, and works with refractors and guide scopes in addition to DSLR and mirrorless lenses.
Will it scratch or damage my lens?
No. The frame has soft protective tips at the contact points, and it clips to the outside of the lens rather than the thread, so removing it won't bump your focus ring or leave marks.
Does it work on any star, or does the target matter?
It works best on moderately bright stars and longer focal lengths. On very wide, fast lenses in especially dark or low-light conditions, a brighter star or planet as your focus target will give clearer diffraction spikes.
How do I use it once it's attached?
Point at a bright star and get roughly focused first, then attach the mask. It splits the star's
light into three diffraction spikes. Adjust focus until the center spike lines up evenly between the other two, then remove the mask to shoot.
