Farpoint Adjustable Tri-Bahtinov Mask — 2.5" to 4.5" OTAs Nebula Bandpass and lands on your secondary

and lands on your secondary

Which Tandem Bar

This filter blocks wavelengths shorter than about 420nm

for which FarpointAstro sells V-size saddles

Farpoint Adjustable Tri-Bahtinov Mask — 2.5" to 4.5" OTAs Nebula Bandpass and lands on your secondaryNot sure this is the right mask for your telescope? Use our Focus Mask Finder match your scope to the right Standard, Tri Bahtinov, or Hyperstar RASA mask. Adjustable Tri Bahtinov focus and collimation mask for OTAs from 2. 5" to 4. 5" front aperture. Sets onto the front of your telescope, gives you focus AND a collimation check from a single short exposure, and lifts off cleanly when you're done. The adjustable peg system fits any scope in this