230mm Metal Bahtinov Mask / Fishbone Calibrator (228-263mm)

Description

Bahtinov Focusing Mask for Visual or Astrophotography (Metal Version)

In Focus Results

• Invented in 2008 by Pavel Bahtinov, these “fishbone calibrators” or “Bahtinov Mask” work by showing a very distinct visual pattern when pointed at a bright star and when you have adjusted to perfect focus.
• These Bahtinov Masks, manufactured by Kson for us, are metal.
• Quad screw design for secure fit
• Precisely engineered and form a lovely, clear and distinct intersecting 3 line pattern when in focus. Top quality, no need to get an expensive brand. You’ll love it.
• Available in 60mm,80mm, 100mm, 120mm,140mm and 160mm, 180mm, 200mm, 230mm and even 270mm fits (see other listings).

Details:

• Measure your inner and outer diameter. If the sizes above fall between one of those ranges, you’ll be right! Feel free to send us a message if your unsure – we will help you!
• Compatible with correctors and barlow lenses

Yep – I want one, how do I figure out which one I need?

Check the product gallery, one of the pictures demonstrates how to measure the mask.  Some of these masks overlap in sizes.  That’s okay – simply pick the one that falls nicely into the range.

Measure across the dew shield.  In this case, it comes out at about 96mm.  I should get the 80mm mask.  The 100mm version will be too much of a fit, and the 60mm mask only goes to 93mm and won’t fit. 

How to use it:

• Attach the mask to the telescope. It is usually attached to the outer diameter, but it can be attached to the inner diameter if you wish.
• Select a medium star with medium brightness and position it in the outer third to get optimal sharpness across your field of view.
• Turn on your camera your camera and watch the star in “live view” mode, or “eyeball it”.
• If not in focus, the central line is shifted. Adjust your focuser until it sits precisely between the other two lines
• Your done! Remove the mask and start exposing your object.