Sunday, September 29, 2013

DIY Paper Bahtinov Focusing Mask

Since my camera doesn't have live view, I have to focus through the little viewfinder. I figured a focusing aid might help me out. I read that a Bahtinov mask could help take some of the guessing out of trying to focus. I found a helpful post about making one yourself, and even a Bahtinov Focusing Mask Generator. I didn't have any black plastic, but I tried my best making one out of paper and it actually wasn't too bad.

Bahtinov Focusing Mask
I printed the image from the Bahtinov Focusing Mask Generator on cardstock

Bahtinov Focusing Mask
...and cut out the white spaces...

Bahtinov Focusing Mask
...which took me about 20 minutes.

Bahtinov Focusing Mask
Then I cut out the disk itself.

Bahtinov Focusing Mask
I wrapped paper around the end of my telescope and taped it for size, then attached the focusing mask with tape.

Bahtinov Focusing Mask
I figured it doesn't really matter if the white or black side faces out. Looks kinda badass.

Even this paper one works in principle - it "produces three angled diffraction spikes at the focal plane of the instrument" (Wikipedia). The problem is that my focuser sticks and jumps, and I only have a course focus. Knowing where focus is doesn't help if you can't accurately make adjustments - I just shoot past it in both directions but can't fine tune it. Oh well, not a bad little project!

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