Forum 2018-08-06T22:58:13+00:00

[Solved] Calibrate Motor Axis  

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HaPeKa
(@hapeka)
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03/09/2018 1:39 pm  

On the instructions I read:

"1) Calibrate the motor's axis of rotation parallel to earth's axis of rotation."

Is there a HowTo that shows, how to do this? In one of the videos it's mentioned, that we have to point the camera to Polaris, that's all ...

What, if I'm heading south to take a Milky Way picture and Polaris is not visible on the north?
Can I take a compass to direct the camera to the north and using the motor to add the correct angle for my GPS position?

Would really appreciate some instructions or links to learn, how to do it.

Thanks!


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JonnyJohn88
(@jonnyjohn88)
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04/09/2018 9:07 am  

Hi HaPeKa,

not the camera has top point to Polaris but the rotating axis of your gear has to be parallel to the rotating axis of the earth. On the northern hemisphere the rotating axis of the earth points to Polaris, on the Southern Hemisphere it is much trickier to find the right point in the sky because there are not many stars around the right spot where the axis is pointing at. Sigma octantis is the Pedant on the Southern Hemisphere. It is not so bright as the Polaris.

But your method with compass and your gps position is a rough estimation for the alignment of your gear. 

On professional Astro gear you have an ocular where can point out the right direction and angle of the motor axis.

This post was modified 3 months  ago by JonnyJohn88

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HaPeKa
(@hapeka)
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Posts: 19
04/09/2018 3:53 pm  

Hi John,

I read about how to align Telescopes to allow long exposure times and I think, I understand the theory behind it.

However, Blackforestmotion offers the possibility to use their motion controller for long exposure night sky pictures and the only explanation, how to do it is: "Calibrate the motor's axis of rotation parallel to earth's axis of rotation by pointing to the north star (northern hemisphere)".

In one of their videos on the kickstarter page they explain the astro mode (scroll down to the mode videos at the bottom of the page).

Blackforestmotion on Kickstarter

I just like to have a short step by step explanation, how to do it with the Pine controller  😀  

This post was modified 3 months  ago 2 times by HaPeKa

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Moritz
(@moritz)
Black Forest Motion Admin
Joined: 4 months  ago
Posts: 2
04/09/2018 9:06 pm  

Hi HaPeKa,

Gunther Wegner from LRTimelapse has a good Tutorial (in German).

https://gwegner.de/tipps/astro-nachfuehrung-tagsueber-ausrichten/

It might help.

All the best,


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HaPeKa
(@hapeka)
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Posts: 19
04/09/2018 10:12 pm  

Thank you Moritz, I've seen this video a few days ago ...
With Pine and the Pan/Tilt unit it would be even easier to do it, as we can use the Tilt function to go to the exact position.

I'm going to try the following steps next weekend to take a Milky Way picture:

1) Level the tripod horizontally
2) Face the camera vertically to the north (with a compass or handy)
3) Start Pine App and tilt the camera in Freerun to the actual Latitude
4) Go to Astro Mode and set the tracking mode to Sidereal or 1/2 Sidereal
5) Move the camera with the sliders in Astro Mode to the southeast towards the Milky Way
6) Start the tracking in Astro Mode
7) Take a picture with the correct camera settings with Intervalometer (Pictures =1 for single picture)

Latitude / Longitude for Berne = 46.948 / 7.447. Therefore, I would tilt Motor1 to 46.95 degrees ...
I'll let you know, how it worked.

 

This post was modified 3 months  ago by HaPeKa

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JonnyJohn88
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05/09/2018 9:09 am  

Hi HaPe, 

I can follow your steps till step 4).

But why do you want to move the axis 5), when it is set parallel to the rotation axis of the earth? if you don't want to make pictures of Polaris you need for example a ball head on your rotation axis to move the camera into another direction.

 

 

 


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HaPeKa
(@hapeka)
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Joined: 4 months  ago
Posts: 19
05/09/2018 3:23 pm  

My understanding (or guess) was:

As soon as I calibrated the the motor's axis the Pine app knows exactly the position of the camera.
When moving the camera afterwards with the two sliders within the Astro mode, the Pine app can calculate the new position and compensate the movement relative to the axis.

What other reasons should the two sliders have, if not that one?

If I need an additional ballhead, I need only one motor to rotate, when I have two, the movement could be recalculated.

The testing with the Nic-O-Tilt motors showed, that Motor1 must be the pan-axis and Motor2 the tilt-axis, both in forward mode when heading to the south. With Motor1 as tilt and Motor2 as pan the movement is too fast and not accurate.

Anyway, I'll do some tests outside next weekend and look, how good it follows the Milky Way  😀    

Any thoughts on that?

 

This post was modified 3 months  ago by HaPeKa

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HaPeKa
(@hapeka)
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Posts: 19
08/09/2018 8:58 am  

@JonnyJohn88

Did some testing last night and you're right. My assumption, that the movement can be compensated is wrong. To fully compensate the movement, you'd need 3 motors and a lot of calculation power ...

As the stars near Polaris turn much slower than the ones further away, it is not possible to have all stars in focus as soon as the axis is not parallel to earth's axis.

I extracted two areas from a picture with a shutter speed of 60s, f=2.8 and ISO 640. the stars on the left are quite sharp, the ones on the right move faster and are not sharp anymore.

Therefore, in my case I'll not going to use movement compensation, it's too complicated with just one motor and an additional ballhead.
I'd rather go back to shutterspeed around 15-20s and ISO 3200. My Sony A7R III is quite good at high ISO, I can get good results with that settings. That's okay for my milky way pictures 🙂


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HaPeKa
(@hapeka)
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10/09/2018 4:41 pm  

Did some testing in Timelapse mode. 
Start went okay, but then I had an issue with the Cables coming in the way of the motion.
Next time I need to check everything with a bit more light 🙂

https://www.youtube.com/watch?v=ufBaKqSIcUI


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JonnyJohn88
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10/09/2018 4:45 pm  

Wow, what a nice shot! can post some of your parameters ( exposure, intervall ... )? 


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Patrick
(@patrick)
Black Forest Motion Moderator
Joined: 4 months  ago
Posts: 18
10/09/2018 8:54 pm  

Hi HaPeKa,

attached is a picture with a possible setup for PINEs astro mode. For that, you are using ONE of the Nic-O-Tilt motors (not the complete pan & tilt head). Important is to align the motor axis with earths' axis of rotation as shown in the picture. On the northern hemisphere, you point it along the arrow to Polaris. A star map smartphone app will also be very helpful for that. You don't align your camera to Polaris. So alignment is all done manually without actually moving the motors in the app. Once the motor is aligned, it is best to use a ball head to reposition your camera to whichever location you like. You can now also rotate the motors using the slide bars in the app to reposition your camera. Just don't touch the actual motor unit again, once it is aligned.

PINE simply rotates the motor very, very slowly, compensating the rotation of the earth (around 1 revolution per 24h). 

Astro mode will NOT work in combination with a motion controlled timelapse move (with slider, pan etc.) as it would change the alignment of the motor used for the astro tracking. However, you can use the intervalometer mode to do a static timelapse, while the astro mode is active. 

If you do a long exposure and some stars are sharp but others are not, the alignment is not correct. It takes some practice but after doing it a few times, it will work well. Important is also to have the motor movement direction correct (either forward or backward depending on your entire setup).

The astro mode is more of a side product of PINE. It is not a perfect setup and alignment might be tricky at first. However, it contributes to the universality of PINE and allows for the astro tracking capabilities with basically any kind of motorized axis. 

Our goal is to release some more instruction videos for the different modes in the next few weeks. We just haven't had enough time lately to work on it.

Best,

Patrick


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HaPeKa
(@hapeka)
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Posts: 19
10/09/2018 10:01 pm  

Hi Patrick,

thank you for the picture. As mentioned, I understood the basics but made wrong assumtions. My fault. 

And it was clear to me, that the Astro Mode is not THE feature I bought the Pine solution for. I know, it's very complex and it was also for me only an add on. But compared to what can be done, there's not too much of an advantage. At the moment, I don't have a ballhead that I can mount easily on the Nic-O-Tilt, therefore I'll not going to explore more on that side. Eventually I'll find a way to add a ballhead to it and then I will do some more testing. However, I'm aware, that calibrating the axis exactly is very very difficult. Every compass coming near the Nic-O-Tilt head starts showing wrong directions due to the electromagnetic field around the device. But, for shutter times around one minute, the approximity is okay ...

And overall, I'm impressed with your solution and I really look forward to take great and impressive pictures and timelapses with the help of the Pine controller   😀 

@JohnnyJohn
I used the following parameters for the TimeLapse with my Sony A7R-III and the Zeiss Batis 18mm f/2.8:
s=15s, f=2.8 Interval 18s

For the timelapse I set a start and an end position and planned for a 20s video at a frame rate of 25 frames per second. When I realised, that the pan was stuck, I stopped the timelapse.


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HaPeKa
(@hapeka)
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Posts: 19
10/09/2018 10:17 pm  

Forgot to mention: ISO 3200 ...


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HaPeKa
(@hapeka)
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Joined: 4 months  ago
Posts: 19
11/09/2018 4:22 pm  

Hi Patrick,
just found a spare ballhead and will try tonight according your instructions ...
If it will be successfull I'll post the results here soon.


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HaPeKa
(@hapeka)
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Posts: 19
12/09/2018 9:54 am  

okay, went out last night and used the following setup as shown in Picture 1.
Motor 1 was used to compensate the movement of the earth axis.
Motor 2 was used for some testing. Works as expected.

Here an example without movement of motor 2, just motor 1 used.
As it was a test, I took 50 pictures for a 2s video, just to test the motion:

https://www.youtube.com/watch?v=R1MA-WAnhyY&feature=youtu.be

Attached two pictures, one of the installation, and one of a 90s shot at ISO 100. 
The compensation is really good, I guess, the axis was quite parallel to the earth axis.

For me the Pine solution is equivalent to Vixen's Polarie, the challenge there is the same, find the right axis  😊 

Set02.jpg
Night90s100iso_4k.jpg

This post was modified 3 months  ago 3 times by HaPeKa

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Patrick
(@patrick)
Black Forest Motion Moderator
Joined: 4 months  ago
Posts: 18
12/09/2018 8:27 pm  

Thanks for sharing your setup. That looks great. Results are also good.

And yes, PINEs astro mode basically does the same thing as the Vixen Polarie once the units are aligned correctly. 

Patrick


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