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This image shows the general shape of the Bahtinov Focus Mask. For more info on this device you can check out this link. http://en.wikipedia.org/wiki/Bahtinov_mask You can make your own mask or order one from this site. http://www.telescopes.com/telescope-accessories/photographic/farpointbahtinovfocusmasks.cfm You will need to pick the size you want and then place your order.
Bahtinov Mask Layout
The upper half of the mask has vertical slits. The width of the slits is not too critical; too small and you don’t get much light through, too wide and the mask is too flimsy. The lower right quarter has slits at about 20 degrees from vertical and the lower left has slits that mirror at 20 degrees in the opposite direction. The angle is not critical but somewhere around 20 to 25 degrees is good. However, both sides should be at the same angle.
This video shows the diffraction patterns produced by the Bahtinov Focus Mask. The Bahtinov Focus Mask has bars in the pattern shown above. The mask is place over the front of the lens so that a special diffraction pattern is produced in the image plane when focused on a point light source. As the lens is moved through focus the horizontal diffraction spike moves in the opposite direction to the two angle spikes. When the horizontal spike is in the middle of the two angled spikes the lens is in focus.
This image shows the general shape of the Bahtinov Focus Mask. For more info on this device you can check out this link. http://en.wikipedia.org/wiki/Bahtinov_mask You can make your own mask or order one from this site. http://www.telescopes.com/telescope-accessories/photographic/farpointbahtinovfocusmasks.cfm You will need to pick the size you want and then place your order.
This image shows the general shape of the Bahtinov Focus Mask. For more info on this device you can check out this link. http://en.wikipedia.org/wiki/Bahtinov_mask You can make your own mask or order one from this site. http://www.telescopes.com/telescope-accessories/photographic/farpointbahtinovfocusmasks.cfm You will need to pick the size you want and then place your order.
This image shows the general shape of the Bahtinov Focus Mask. For more info on this device you can check out this link. http://en.wikipedia.org/wiki/Bahtinov_mask You can make your own mask or order one from this site. http://www.telescopes.com/telescope-accessories/photographic/farpointbahtinovfocusmasks.cfm You will need to pick the size you want and then place your order.
See photo in original gallery.
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