Aluminum Alloy Bahtinov Focusing Mask Telescope Caliber Fixed Diameter 60-270mm

Descriptions:
1. The Bahtinov Mask Made of aluminum alloy, not plastic. And it has whole anodizing aluminium process, which is durable and has good performance in long-term use.
2. This focusing mask can be used for a variety of purposes, such as camping, hiking, fishing, hunting, and other outdoor activities.
3. Masks now feature 3 holes which can be attached with 3 screws to prevent the mask from falling all the way to the ground
4. Perfect focusing for your CCD, DSLR or Webcam in seconds
5. Light weight so you wont upset the balance on your scope
6. Suitable for telescopes front end diameter 60mm to 330mm according to different sizes
7. Universal adaptation, 3 bolts with plastic cover allow the mask to be simply attached to any telescope
8. Aluminium alloy material thickness: 1 mm
9. Color: Black

Note :
1. When you buy it, you need to check your out-diameter of the tube. Not just the Objective lens diameter, because you need to put the item on the tube.
2. If you don't know which size should to choose you can ask us before buying it, Thanks
3. Place the Bahtinov Focus-Mask over the end of your telescope, then locate a bright star near your target, take a 3-5 seconds picture and view the diffraction spikes. Change your focus, take another picture and again, view your diffraction spikes. Is the center spike moving further from center? Then change the direction your focusing and try another picture. Watch the direction the spikes are moving and when the center spike passes the middle of the other two spikes, change direction and fine tune your tuning knobs until the center spike is in the middle. Your now in perfect focus.
 

SKU

Normal Size

Telescope
tube min outer diameter(appr.)

Telescope
tube max inner diameter(appr.)

Sample compatible telescopes

A27-60

60mm-90mm

60mm

90mm

small camera lenses or small refractors like the TS 50mm APO. INED70 or other 60-80mm refractors etc

A27-80

80mm-110mm

80mm

110mm

80、100 or 120mm ED Skywatcher and other refractor

A27-100

100mm-140mm

100mm

140mm

100、120mm Skywatcher refractors Celestron 4 SE

A27-120

120mm-160mm

120mm

160mm

127mm Celestron or Skywatcher Maksutovs. meade 127 ED APO. Celestron 5SE

A27-140

140mm-180mm

140mm

180mm

 6' Skywatcher or Celestron Newton C6 SCT  

A27-160

160mm-200mm

160mm

200mm

7' Maksutovs

A27-180

180mm-220mm

180mm

220mm

8'Skywatcher or Celestron Newton

A27-200

200mm-260mm

200mm

260mm

8'Skywatcher or Celestron Newton. C8 SCT

A27-230

230mm-290mm

230mm

290mm

10' Skywatcher or Celestron Newton. C925 SCT

A27-270

270mm-330mm

270mm

330mm

 12" Skywatcher Newtonians. C11 SCT