My Barn Door Build

[Ajohn]

I am swaying back to electronic, this site makes me think I could do a paint by numbers and have a go.

http://fstop138.berrange.com/2014/01/building-an-barn-door-mount-part-1-arduino-stepper-motor-control/

That's an interesting one - seems to be correcting the error in a simple scotch mount with software by changing the switching rate every min.  Sort of calculated PEC. Personally I would add a microswitch to pick up when it had been reset back to the start position which needn't be when it is completely closed, just some angle that represents some "sidereal start up time".

John

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[happy-kat]

I have upgraded the ballhead I use for the camera, the new one (still inexpensive at £15 but twice the price of the one I had used) is much easier to move the camera around on.

[happy-kat]

The top board now has a switched red LED bulb to light up the turning CD.

[happy-kat]

I took this frame of comet Lovejoy (which was the spark for making the tracker) back in January 2015 and it is a single 180 second exposure using my home made manual barn door tracker mount detailed in this thread. I set it up sitting on a chair in our drive way and looking at that image the elevation was high and pointing south west. Sadly I did manage 3 images of 180 seconds but comet Lovejoy had got to the gutter by then as this image was the first.

Canon 1100d with vintage 50mm lens ISO 800, 180 second exposure at I would imagine f2.8 Edit: might have been wide open looking at the corner aberations

 

[happy-kat]

Have ordered another arduino board that this time wont require me to get the soldering iron out as it has those liittle sleeves on each contact so I will be able to just push the wire clips in.

[happy-kat]

The barn door may get used tomorrow so finally got round to soldering the connections on the red led light that will be mounted to shine down onto the turn handle.

[happy-kat]

Yey I got to use it last night. I've fitted a rdf though it is not yet aligned. It's really nice to use and peaceful being without motors or battery etc.

[happy-kat]

Red dot finder now alligned as best as possible before actually checking against Polaris. Friday is looking possible for a short test.

[happy-kat]

Been reviewing the recent images taken, all 48 were usable (barring clouds) and have been practicing turning the handle (it's cloudy). I don't think the jitter images (when viewed to fit this monitor they all look fine it is only pixel peeping that reveals imperfections) are because of the captive nut jumping as the underside of the top board surface is laminate/formica and allows the nut to slide. I'll use the 40mm lens next try which gives me 10 second space and with the rdf now roughly aligned should give a better Polaris alignment. I need to be careful of not getting ahead of time when winding. If I still have too many images that aren't perfect I will consider trying a Teflon patch where the captive nut contacts the top board. I can minimize any osculation in the bolt by how turn the handle.

[happy-kat]

Got to go out last night. The red dot finder is not there yet as it was pointing a good inch above Polaris so it just provided a better than guess work alignment but needs more tweaking.

I still took one 3 minute exposure which doesn't look too bad, jpeg attached.

I did find that as long as I kept behind the clock I had better chance of good star shapes. Using a 40mm lens gave me a 10 second window.

 

That's a street light lighting the neighbour's hedge.

[happy-kat]

Red dot finder was actually an inch below which makes sense for parallax error, Polaris is the only object I can use to fine tune the alignment as nothing else is high or far enough away.

That's my first single image where the milky way is seen. Currently stacking the evening's take...

[happy-kat]

Just thought I would add the link to a page where I got the calculations for the barn door build bolt to hinge.

link here