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INDI Library v1.8.1 Released (09 Sep 2019)

Monthly maintenance release INDI v1.8.1

New Bahtinov Mask Assistant Tool

10 months 4 days ago
sneubert
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New Bahtinov Mask Assistant Tool #34550
Dear all,

I have started to make a prototype for a Bahtinov aid, which eventually I would like to put into the EKOS Fokus module.
The idea is the same as with the tools available in APT or the Bahtinov grabber. Since I wanted to understand the problem (and Bahtinov grabber is not very well documented) I developed my own solution in the form of a likelihood fitter.

I attach a few examples what the Bahtinov fitter can do at the moment. For the examples on the Wikipage ( en.wikipedia.org/wiki/Bahtinov_mask ) it can correctly identify the two out of focus pictures, by measuring the displacement of the center line (shown in green) with respect to the two crossing lines.
So I am quite happy and think I understand the problem well enough to start thinking about how to put this into EKOS.

If you guys can send me example shots taken with your Bahtinov mask I would be able to see how robust the fitter is. That'd be super helpful!
Also, the framework can easily be adapted to fit non-standard mask shapes. If you have one of those, please send me the specs and pictures.

If there are suggestions what you would like to see in such a feature I can try to accommodate this.

Thanks!
Sebastian
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10 months 3 days ago
knro
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New Bahtinov Mask Assistant Tool #34561
Sebastian,

This is awesome! Many users have requested this feature before. Though I am quite spoiled with the autofocusing and my bahtinov mask is collecting dust now :P

Jasem Mutlaq
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10 months 3 days ago
wvreeven
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New Bahtinov Mask Assistant Tool #34568
Sebastian,

Many thanks for this effort!!! Let me know if you need testers for the module. I'll try to collect some images and will share them with you. When I image with my Canon DSLR I always take RAW images (i.e. CR2). I hope that's not a problem?


Cheers, Wouter

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10 months 3 days ago
sneubert
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New Bahtinov Mask Assistant Tool #34571
Hi Wouter,

Canon raw files should be fine. I'll need to learn to work with FITSIO anyhow, which can handle them. For initial testing I can just convert them myself.

Cheers, Sebastian

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10 months 3 days ago
knro
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New Bahtinov Mask Assistant Tool #34572
The focus module switches the mode to FITS when it captures images from DSLRs so you don't need to worry about converting them.

Jasem Mutlaq
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10 months 3 days ago
sywong2000
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New Bahtinov Mask Assistant Tool #34573
Awesome!! most wanted feature!!!

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10 months 3 days ago
sneubert
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New Bahtinov Mask Assistant Tool #34574
Hi Jasem,

I'll need to make an option to import pictures into EKOS for testing purposes, I guess I can copy how that is done in the alignment module, right?
Also if you can point me to a piece of code where a FITS picture is read into a 2D array, that'd be helpful.

Thanks, Sebastian

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10 months 3 days ago
Ihoujin
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New Bahtinov Mask Assistant Tool #34600
Fantastic! I have been hoping to see this one day. I have a number of bahtinov examples to share since I've been producing masks made from acrylic for people. I will also point you to this tool Maskulator To simulate bahtinov masks.

Here are a bunch of assorted bahtinov mask samples.
Dropbox Samples

Hope these help.

Andrew.

INDI/KStars on Raspberry Pi 4, 4gb
Raspbian Buster with AstroPi3 script configuration
Skywatcher HEQ5 Pro Mount
Canon 600D Camera
Orion SSAG/ASI120mm @280mm Guide Scope
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Adafruit Motor Hat shield
Adafruit GPS Module
Generic Bluetooth Joystick.
Startech 7 port powered USB Hub.
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10 months 3 days ago
sneubert
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New Bahtinov Mask Assistant Tool #34605
Dear Andrew,

This is exactly what I was looking for. Many thanks!!

Sebastian

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10 months 2 days ago
totoantibes
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New Bahtinov Mask Assistant Tool #34630
note that APT has already built in this module: ideiki.com/astro/usersguide/bahtinov_aid.htm maybe this iswhere the idea iscoming from

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10 months 2 days ago
sneubert
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New Bahtinov Mask Assistant Tool #34633
Indeed as I wrote above APT is one of the inspirations for this.
I'd be curious for suggestions how we can be better than APT. E.g. the two circles that indicate the Focus error in APT.. are they really useful? Why use circles here? What is measured is just a single number.
Instead what I want to provide is an uncertainty of the measurement, so that the user sees when they have reached the sensitivity of the method and further tuning becomes pointless.
This can be expressed visually through a "Focus achieved" message.

BTW: is color vision deficiency (CVD) a design consideration in KStars? Might be an issue when we use differently colored indicators.

Cheers, Sebastian

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10 months 2 days ago
Ihoujin
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New Bahtinov Mask Assistant Tool #34651
I believe the circles in Bahtinov Grabber / APT implementation show a scaled up magnitude of error and whether it is inside or outside focus. It's intuitive enough to get the circles to overlap as much as possible. The software is also capable of averaging over a number of frames to combat seeing conditions.

INDI/KStars on Raspberry Pi 4, 4gb
Raspbian Buster with AstroPi3 script configuration
Skywatcher HEQ5 Pro Mount
Canon 600D Camera
Orion SSAG/ASI120mm @280mm Guide Scope
PHD2
Adafruit Motor Hat shield
Adafruit GPS Module
Generic Bluetooth Joystick.
Startech 7 port powered USB Hub.

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