3D Astro Bahtinov Focus Mask - 138mm ID
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Bahtinov mask to aid in focusing your Askar 40mm Guidescope # FMA180. Will also work for similar scopes which have a dewshield outside diameter of 52mm (check your guidescope before purchase if you are not sure).
We're not sure how necessary or effective this might be on a small-aperture guidescope, but several people have expressed interest in this item, so here it is.
With the mask on, you can see a diffraction spike pattern. Focus until you achieve a symetrical pattern. Once the best focus has been achieved, you can remove the mask and use the guide scope as normal.
This mask is deliberately designed to fit loosely over the guidescope dewshield so that it can be removed very easily when focusing is accomplished. It does not have a firm fit like an end cap would so that the imaging setup isn’t disturbed when you take this off.
3D printed from PLA.
Color of current stock is silver-gray but is subject to change without notice.
| Product Banner Type | new |
|---|---|
| Free Shipping Graphic | Free US Shipping |
| Hide Found a better Shipped Price on Frontend? | No |
Bahtinov mask to aid in focusing your Askar 40mm Guidescope # FMA180. Will also work for similar scopes which have a dewshield outside diameter of 52mm (check your guidescope before purchase if you are not sure).
We're not sure how necessary or effective this might be on a small-aperture guidescope, but several people have expressed interest in this item, so here it is.
With the mask on, you can see a diffraction spike pattern. Focus until you achieve a symetrical pattern. Once the best focus has been achieved, you can remove the mask and use the guide scope as normal.
This mask is deliberately designed to fit loosely over the guidescope dewshield so that it can be removed very easily when focusing is accomplished. It does not have a firm fit like an end cap would so that the imaging setup isn’t disturbed when you take this off.
3D printed from PLA.
Color of current stock is silver-gray but is subject to change without notice.
| Product Banner Type | new |
|---|---|
| Free Shipping Graphic | Free US Shipping |
| Hide Found a better Shipped Price on Frontend? | No |
3D Astro Bahtinov Focus Mask - 138mm ID # BM-S-138