Quote:
Originally Posted by bojan
On the third link is a variant of Bahtinov mask with threads..
I was always wandering if I can build something similar to tennis racket (but with thread pattern that will produce diffraction spikes useable for focusing.
This guy was a bit faster than me...  |
The Mewlon has a 3 vane spider which effectively acts in a similar manner to the Bahtinov Mask when the OTA is pointed at bright stars.
The image generated by the 3 vane spider is not as clearly defined as the image generated by the Bahtinov Mask, especially on fainter stars, so focus is easier to establish and far more certain due to the multiple diffracting elements of the Bahtinov Mask.
For laymen such as myself, who wouldn’t know a Fast Fourier Transform if it hit them on the head, regardless of whether it was in the time or frequency domain, I find the diagrams and explanations both on IIS and CN very educational and fascinating to read about.
Cheers
Dennis