If between each capture the focus is done with HFR with EKOS in-focus-sequence, is the temperature measuring remain useful ?
Is a temperature calibration of the automated focuser mechanism necessary ?
If it is I imagine that it make more complicated to keep the calibration parameters constants.
Another question is about absolute and relative focusing. What is the best one ?
I have an opinion about it but not sure I am true.

This was posted about a year ago in a topic started by me when I was developing my focuser. Hope it is useful to you.

If you search by my username and "DIY focuser you should get it.

I have created an easy arduino micro based focuser for my FS-60 a while ago.

github.com/ppapadeas/takahashi-fs60-focuser

It is open hardware. If anyone is interested I can port it to KiCAD for additional development. I think it worths it to keep developing an open source solution like this (properly licensed)

You can also check Astroberry Focuser in this topic - home made focuser based on Raspberry Pi.

Hi!

Ppapadeas,

Seems great! Can I specifically ask you about the blue and yellow triangular wedges, on the last to images on your site - for physically attaching the stuff to the scope. What are these, and made of what?

Magnus

Those are custom designed holders, designed in FreeCAD and printed in a TAZ4 3D Printer. All designs are available in the github repo.

Hi!

Patdut, I now have assembled the whole DIY focuser (version 2, found here: sourceforge.net/projects/arduinoascomfocuserpro2diy/) and have it running with the windows software. So far so good!

Next step is to connect it to Indi. I have the DRW8825 driver board, so the moonlight driver you pointed to would not work. However, it is supposed to work with the verion 1 of the same project. I'll try that and get back. How is you project doing?

And, by the way, what is specifically meant by "absolute" focusers?

Magnus

Hello Magnus,
The mod blackdragon72 software (sourceforge.net/p/arduinomoonlitefocuser...code/ci/master/tree/) works fine with the basic setup I use ULN2003A controller + stepper motor 28BYJ-48-5. I tested only the principle, I mean I connected the stepper motor to controller the controller to the arduino and the the arduino to the computer. I flashed the arduino with mod software and :woohoo: it worked fine.
I guess, as the implied by the name, the DIY focuser is an ascom focuser. I don't know if it can be handled by indiserver. Maybe Jasem can enlighten our mind on this topic.
I must admit that absolute and relative notion made me a little bit doubtfully. I guess that relative means that the displacement of focuser is coded as positive or negative number, and, for absolute, the position value is coded always as positive integer. Meaning that you define a great positive value as origin and move forward and backward of this positive value. Maybe, again, Jasem can enlighten our mind on this notion.

The work I have to do now is to install the stepper motor on my focuser for a better testing. Not a easy task to do it without damaging the nice focuser of the AT 111/777.
Doing a lot of designs to avoid drilling holes in it. Still working to find the better solution. My last design implies a 3d printed bracket stuck on the focuser body with a strong double sided adhesive and a toothed belt. This step looks to be the more difficult in my opinion.

Patrick

An absolute focuser can always know its position on start-up. While a relative focuser always assumes home or zero position on start-up. For example, suppose we have one absolute and relative focuser, and both initially at home zero position (both reports 0 ticks), which is when the draw tube is all the way in. If you ask them to "Focus Out" 1000 ticks, both would go to the same position. If you power off, and then connect again, the relative focuser will report a value of 0 ticks, while the absolute focuser will report a value of 1000 ticks.

I understand better why in blackdragon72 arduino software there is a EEPROM store of the position after a long lapse of inactivity. Something I don't understand how is it possible to go from the all way in position of the tube to the closed focus position with only 60000 steps if you use (as I wanted to do) the 1/10 knob to move the focuser ?
I guess it is necessary to travel the focuser manually to the closed focus position power on the focuser, connect it under ekos and lets the software do the rest.

Just a question Jasem, is it necessary to correct the focus with temperature if it is possible to do an automatic focus between two shots (and is it possible) ?

sourceforge.net/projects/arduinofocuscontrollerpro/

This project indeed runs under INDI. you just connect it up and select the moonlite driver.
Many users are doing this
Regards
Robert