Farpoint DSLR Camera Filter unmounted Bahtinov Mask, FP441. | Fast Easy Focus for Your astrophotos a lifesaving Tool for Focusing Your Astro Camera or DSLR.

Farpoint DSLR Camera Filter unmounted Bahtinov Mask, FP441. | Fast Easy Focus for Your astrophotos a lifesaving Tool for Focusing Your Astro Camera or DSLR.

• Bahtinov focus mask for 67mm filter threads. Snap into a inexpensive UV filter and then thread into your camera lens. Allows for precision focusing of your wide field shots.
• Bahtinov focus masks make focusing for astrophotography fast and easy. Ends the pain of struggling to find the best focus for your astrophotography images.
• Works with all electronic imaging devices. Includes DSLR cameras, modified DSLR cameras, CCD astro-imagers, CMOS astro-images, video cameras, low light systems etc.
• Use by simply placing the Bahtinov focus mask over the end of your telescope, record a quick image of a bright star, adjust focus and repeat two or three times until perfect focus is achieved.
• Made in the USA by Farpoint Astro. Made in America, by Americans, using American made materials and suppliers, supporting our economy. Buy American please.

Focusing with your Bahtinov mask is simple. Start by snapping the Bahtinov mask into an inexpensive UV or Skylight filter that fits your camera lens. [FILTER NOT INCLUDED, MUST BE PURCHASED SEPARATELY] Center a fairly bright start in your camera and achieve a rough focus, then loosely screw the filter holding the mask onto your camera lens. Take a short exposure. The image of the star will show diffraction spikes. The "center" set will most likely be shifted to one side or the other. This is showing the defocus. Adjust the focus of your camera and re-expose the star, once again showing the diffraction spike pattern. Iterate the process until you get the central diffraction spike centered against the star and the other spikes. When you achieve a symmetrical pattern, you have achieved the best possible focus. Remove the mask, center your target object and take your images!