DIY Wedge: more control!
Posted by: Owen, 20 Oct 2009 18:02
Last week I finally got around to adding an azimuth fine tuning controller to my diy equatorial wedge, which is little more than a bunch of M6 fittings fixed to both the wedge body and one of the bolts that attaches wedge to the tripod. I only just got around to it as I the original bolts I got for the tripod were not long enough (there were in fact flush to the tripod body), so I had to go to a specialist trade shop again to get the mtyhical UNC thread bolts and nuts.

When the tripod bolts are loosened I can then use the wing nuts on the side mounted azimuth control to make slight adjustments to the azimuth angle when attempting zero in on Polaris while doing a 'wedge align' as a part of the equatorial alignment setup; there is enough give on the size of the bolt holes on the wedge to allow some rotational movement.
Hopefully this works out better than the disastrous results that come with picking up the entire gear and trying to shift it slightly one way or the other!

Now I just need some clear skies... on a night that is not too cold please!

DIY Wedge 1 DIY Wedge 2 DIY wedge 3 DIY Wedge 4 DIY Wedge Azimuth Control DIY Wedge Azimuth Control
Tags: DIY wedge, Astrophotography
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More questing for the stars!
Posted by: Owen, 29 Aug 2009 18:21
My quest for long(er) duration astrophotography has been a bit hit and miss. Mostly miss.
There are three basic system that I need get working correctly before I can even take one simple shot successfully; focusing, camera control, and alignment.

Focusing may seem like a trivial issue to deal with but my camera tries to make it as difficult as possible. My Canon EOS 10D was the last model of its line that went without any sort of Live View functionality, which means that you cannot use the cameras LCD screen (or better yet a computer screen, i.e. Remote Live View) to view the scene before taking a shot in order to get good focus. The only way to focus the telescope with the camera attached is to use the cameras viewfinder. At the best of times it isn't easy to actually see any stars through the tiny viewfinder in order to get a fine focus; then throw the usual light pollution into the mix. If you reposition to a star that you can actually see you may be bending over backwards just to actually be able to see through the viewfinder at all.
But then when you think you are actually focused, with lovely pinpoints of light for stars, what ends up on the exposure are big blobs of light.

I thought this focusing issue was going to be the main thing holding me back and that I'd probably be better off just getting a different camera, but I eventually found a little program called DSLR Focus that takes a series of quick shots and allows you to slowly tune in to a fine focus (and you can be sure it is focused!). The same could be done manually with some of the Canon utility programs, but the mere thought of doing it that way would just make me want to give up the whole thing.

So focusing solved, what about controlling the actual taking of pictures?
Typically DSLR cameras on their own can be set to take exposures of up to 30 seconds in duration. If you want to go for longer you need to use the 'bulb' setting and use an attached triggering device. The ones you can usually find a manual triggers, either wired or remote, but I'd want to be able to take a series of specifically timed exposures, preferably using a program like Strak-Labs DSLR Shutter. So I'd need a way to trigger the camera via the computer. I found the schematic for such a thing, which looked simple enough, so I got out my rarely used soldering iron and had a go at putting it together.

It's not the prettiest thing in the world (maybe I should actually go join the local hackerspace and learn how to solder properly), but it does work... well, at least some of the time. I've had it out at night with the telescope once and although it was triggering the shutter it wasn't holding it open. I've since gotten that to work with changing a setting in the program (for some strange reason I ignored the setting labelled for the Nikon D200).
But then yesterday I decided to try to use it to take shots for a time lapse video test, but it failed to work at all! I ended up connecting directly to a USB-to-Serial cable, bypassing my hacked together monstrosity, which may or may not be entirely healthy for the camera but it worked this once.

Over an hours worth of boring clouds in 20 seconds

So I'll need to figure this one out before attempting to use it with the telescope again.

But that isn't what is really keeping me from taking a decent astronomy photograph. It is the alignment that is holding me back.
I think my inability to cut or drill straight is coming back to haunt me, because right now the wedge just doesn't seem to be working out too well. Every attempt at alignment so far has been waaay off, with a five minute exposure leaving a lightning blot like zig-zag streak.
One issue is that I may just be setting the altitude angle wrong, as I don't have a relatively easy way of actually setting the angle (the threaded rod is great for actually changing the angle, but I'm just not quite sure what angle it is actually at).
The other issue is a complete lack of any sort of azimuth fine control. If I want to alter the azimuth I have to actually move the tripod itself, which is... eh, not ideal.
There are a few adjustments I might try in order to overcome these problems.

I knew from the start that the wedge just might not work out in the end, but I'm not giving up on it just yet. I put too much bloody work into it!
Tags: Astrophotography, Canon 10D, DIY wedge, timelapse, hacking,
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DIY Astronomy
Posted by: Owen, 22 Jul 2009 05:35
When I was a kid I wanted a telescope. So one day I got together what money I had, probably the proceeds of a birthday or christmas, and went into town with my mother to buy a scope. It was just going to be a simple refractor aimed at kids, probably good enough to make out the planets but little more - not that I knew what a refractor was, let alone it's capabilities.

We got up to the counter and there on the shelf was what we were looking for. I was ready to hand over my money and begin my new career as an astronomer. I was excited!
But then I saw something else on the shelf beside the telescope... and I get even more excited!

[Read more...]
Tags: Astrophotography, NexStar 6SE, Canon 10D, Canon 40D, DIY wedge, Moon
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