Project - camera based collimator for Newtonians

[paul]

I have used  traditional methods for collimation of the secondary (e.g using a cheshire sight tube) but my eyesight is a bit sub-optimal so I often finish using a webcam in conjunction with Sharpcap to ensure my secondary mirror is positioned accurately. Particular care is needed if  you want even illumination on you astro-camera sensor. I use a cheap webcam with a fixed focus, lashed up to the focuser. Then I use Sharpcap to manually add concentric circles to help me centre the secondary and get the angles to show it as a circle.  The downside of this lash-up was it was a lash-up - tricky to set the circles accurately and tricky to see all the details of the optical train. What I really needed was a camera that I could remotely focus and finely adjust the image settings  - with software specifically designed for the job.

 

The OCAL collimator has recently been launched and shows what a complete professional package can do - full collimation that is simple, accurate and quick with no squinting at laser beams. The USP is that you can remotely focus the camera at each stage of the light path to set things up with precision and it comes with useful software. I was really tempted to buy it.  

 

But I've just stumbled on an Arducam 5Mp Autofocus (£14) for the Rpi (somehow knowledge of its existence has completely passed me by and its been out for some while). I did a quick google but can't find anyone using it for collimation. Control is very simple, any Rpi with a CSI port can control it. Playing around this evening I can already see how the solution will work. My first build will use an RPi3 B with SW written in Python. If it looks promising I'll try and buy an RPi W for a compact wireless solution. I may convert it to the new Raspian camera library if I can see the benefit. 

 

The trickiest bit for me will be attaching the camera to the scope in a stable repeatable way - is anyone with a 3D printer interested in such a project?

 

Got to do something on these cloudy night! 

 

 

 

 

 

 

 

 

 

[AstronomyUkraine]

18 hours ago, paul said:

I have used  traditional methods for collimation of the secondary (e.g using a cheshire sight tube) but my eyesight is a bit sub-optimal so I often finish using a webcam in conjunction with Sharpcap to ensure my secondary mirror is positioned accurately. Particular care is needed if  you want even illumination on you astro-camera sensor. I use a cheap webcam with a fixed focus, lashed up to the focuser. Then I use Sharpcap to manually add concentric circles to help me centre the secondary and get the angles to show it as a circle.  The downside of this lash-up was it was a lash-up - tricky to set the circles accurately and tricky to see all the details of the optical train. What I really needed was a camera that I could remotely focus and finely adjust the image settings  - with software specifically designed for the job.

 

The OCAL collimator has recently been launched and shows what a complete professional package can do - full collimation that is simple, accurate and quick with no squinting at laser beams. The USP is that you can remotely focus the camera at each stage of the light path to set things up with precision and it comes with useful software. I was really tempted to buy it.  

 

But I've just stumbled on an Arducam 5Mp Autofocus (£14) for the Rpi (somehow knowledge of its existence has completely passed me by and its been out for some while). I did a quick google but can't find anyone using it for collimation. Control is very simple, any Rpi with a CSI port can control it. Playing around this evening I can already see how the solution will work. My first build will use an RPi3 B with SW written in Python. If it looks promising I'll try and buy an RPi W for a compact wireless solution. I may convert it to the new Raspian camera library if I can see the benefit. 

 

The trickiest bit for me will be attaching the camera to the scope in a stable repeatable way - is anyone with a 3D printer interested in such a project?

 

Got to do something on these cloudy night! 

 

 

 

 

 

 

 

 

 

I just watched a video on Youtube demonstrating the OCAL collimator, it looks an impressive piece of kit. Quite inexpensive in astro terms.

 

[paul]

Yes, if I get bogged down with issues I may go the pro route. 

 

Sofar I have the Arducam working with full manual focus control with an image refresh every 0.3s. Focus can be adjusted from about 30mm to infinity.  Now to add all the widgets a circle overlays. 

[Demon]

I've had various attempts at collimation and used various methods from cheshires, laser to camera with overlayed circles. I'm not really happy with any, as an engineer I'm used to verniers and eyeballing to get it perfect for astrophotography just doesn't leave me as happy as if like to be. The ocal does look very nice. Much of my problems I think how have been more down to packaging, fit and finish, as whatever I use it it doesn't fit snuggly and perfectly square to the focused then will lead to error. It has to be consistent with how the camera is held. Not sure if I'm overthinking or heading in right direction. It looks like this has been an area you've been looking at for sometime including laser crossed like mine. I'd greatly appreciate knowing what your current views are not only on potential solutions but also your views on the multitude of potential problems through your journey into achieving good enough collimation for AP. Thanks very much...