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Farpoint Bahtinov Focus Mask for 58 mm DSLR Camera Filter Threads - FP439


Farpoint Bahtinov Focus Mask for 58 mm DSLR Filter Threads

This snap-in Bahtinov Focus Mask is designed for DSLR camera lenses that have 58 mm filter threads. The Bahtinov focus technique is best suite for instruments with longer focal lengths. Its usefulness is diminished with shorter focal lengths. Approximately 100 mm focal length or longer is the functional useful limit. (Focal length should not be confused with camera lens size).

More About Bahtinov Focus Masks

Bahtinov Focus Masks were first conceived by Pavel Bahtinov, a Russian amateur telescope maker and astronomer. This essential tool for astrophotography is made from virtually indestructible ABS plastic. The Bahtinov Mask provides an intuitive new way to streamline DSLR, webcam, or CCD camera focusing for astrophotography.

With your camera attached to a telescope, center an adequately bright star in your telescope to obtain a rough focus. Next, install the mask over the telescope's front aperture by "hanging" it on the plastic screws from the front dew shield and take a short exposure. The star image will display diffraction spikes. The "center" set will probably be shifted to one side or the other, exhibiting defocus.

Modify focus and re-expose the star to demonstrate the diffraction spike pattern again. Repeat this procedure until the central diffraction spike is centralized against the star and other spikes. You'll know you've attained the highest achieveable focus when you have a symmetrical pattern. Remove the mask, center your desired target, and take your images!