FoFi - A free, automatic telescope focus finder software

Focus Finder

This article is about a new piece of software I developed over the past few years: A telescope focus finder software for Linux (and maybe later Windows).

At the time of publication this project is not even in ALPHA state. However, I feel now is the right time to publish it since it reached a state where at least the source code could be useful to others. You can find the source code on github here.

The software aims to support the amateur astronomer (and especially astrophotographer) with one of the most critical but also most annoying tasks: Finding the best focus position for the camera. The main goal is to provide a free and easy to use software that just does the job - automatically.

With a given configuration it should also be possible to execute "FoFi" from the command-line without requiring any user interaction. This way you can include a call to the Focus Finder into a script. This might be useful if the entire observation process should be automated and you want to re-focus from time to time to compensate the temperature drift.

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Fast "max entropy" thresholding for 16 bit images with CImg

In this article I shown a C++ implementation of the "max entropy" threshold algorithm using the CImg library. This implementation also performs for 16 and 32 bit / float images.

First, a little bit of context: Some time ago I implemented the OTSU threshold algorithm as a pre-processing step for image binarization. I used that threshold algorithm to distinguish the noise pixels from the potential "star" pixels. This worked quite well for the high contrast input images at that time. However, for weak stars it unfortunately failed badly.

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The new Cherenkov Telescope on La Palma

End of 2018 I visited the new Cherenkov Telescope on La Palma. Actually I planned to write a long article about this visit - but as it happens sometimes, other things are more important... I decided to skip this article since now there is sufficient information out there about this telescope. However, I think the images I took for this article are still worth to see and give an impression from the observation site on the Roque de Los Muchachos on La Palma. The following two links provide more information about the CTA on La Palma:

Clear skies!

An article from in the "Dark Sky Travels Magazine"!

Recently Dark Sky Travels Magazine contacted me and asked if they could publish one of my blog articles in their magazine. The article describes how one can use DeepSkyStacker to stack conventional DSLR camera RGB frames. Of course I didn't say no and in the end it just happened and I saw my article on page 42/43 in Issue 4 of the DarkSkyTravels magazine!

I am very happy about that opportunity and the chance to share my experience this way.

Thanks and clear skies!