Sharpstar2 focusing filter

Started 3 months ago | Discussions thread
Lyle Aldridge Senior Member • Posts: 1,102
Re: Sharpstar2 focusing filter

Tom59 wrote:

Have any of you used this for focusing? If so what are your thoughts?

I currently use magnified live view but my eyes arent what they used to be. And I have a Lee filter holder already.


I haven't used that specific filter, but it seems to be just a Bahtinov mask made to fit a square filter-holder. I've been making and using Bahtinov masks for several years on telescopes, and they work great. Put a star of 1st or 2nd magnitude in the field of view, turn the ISO up to 6400, and set the shutter to Bulb, and the pattern created by the mask is very visible in magnified live view. I don't even have to make any test exposures. I just adjust focus until the middle spike is exactly centered, and tighten the focuser lock screw.

Others here have been using Bahtinov masks on camera lenses, but I don't know whether they're able to forgo the test exposures.

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