A Fourier method for the determination of focus for telescopes with stars
Abstract
We introduce a Fourier method (Fm) for the determination of best focus for telescopes with stars. Our method fits a power function, that we will derive in this paper, to a set of images taken as a function of focuser position. The best focus position is where the power is maximum. Fm was first tested with small refractor and Schmidt-Cassegrain (SCT) telescopes. After the successful small telescope tests, we then tested Fm with a 2 m Ritchey-Chr\'etien-Coud\'e (RCC). Our tests show that Fm is immune to the problems inherent in the popular half-flux diameter method.
Cite
@article{arxiv.2201.12466,
title = {A Fourier method for the determination of focus for telescopes with stars},
author = {C. Y. Tan and B. Schulz},
journal= {arXiv preprint arXiv:2201.12466},
year = {2022}
}
Comments
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society (MNRAS) Published by Oxford University Press on behalf of the Royal Astronomical Society