My astronomy project:
Repair of Star Adventurer
1: Overview of the parts and an inside look for broken parts
I already have the EQ6 mount and it's working well for me. But sometimes when I travel I want to bring with me some lightweight mount and the EQ6 is for sure not that. Then I found this SkyWatcher's Star Adventurer. It was broken and I got it cheap. It had been broken by accident when it hit the floor and some parts was bent. And it has a terribly backlash and there is noise from the gearbox too. It was a chance of course to buy this. But I like the look of it and I couldn't stop me from buying it.
The look of it give the feel that it is of high quality and with the red paint it look nice. In Sweden it cost about 280 Euro as new.
The knobs to the left are for the altitude and azimuth adjustment, the middle one lock the altitude adjustment. To the right of the knobs there is a port for guide camera connection. The switch for north or south.
Under the grey cover is the battery compartment, it holds 4 AA batteries, it's also possibly to power it from a mini USB with 5 volt.
There is also included a polar scope. A must if you want to use any longer focal length lenses. They max recommend 50mm, but I have read of people who use 300mm lenses, then there is a need of guide camera. Star Adventurer has a connection port for guiding.
The wedge, very advanced with a worm gear (04:a) to adjust altitude, it also handle high altitude as where I live 60 degree and up to 75 degrees.
One sign of what had happen, a bent screw (05:a) which adjust azimuth angle. I think it's made of brass.
No damaged to the cast part. Just have to order a new adjust screw, maybe not necessary, it works already but with some limitations.
After open it I got a surprise, what a high quality to be just a simple star tracker. But because it's broken there are some parts that doesn't work. Very high backslash and stiff gears. (06:a) the DC motor.
A highly integrated control device mounted in the lid, looks good. To the left, ports for guiding and a mini USB for power inlet when not used with batteries.
Worm gear with the big gear bottom right, a very heavy construction in a small case. Even this part is very loose, the shaft can be moved about 2 mm. Can't see any damage, maybe just to adjust, but how can it be so poor adjusted then?
There is no stepper motor, a more modern technology with a DC motor (09:a) and a pulse sensor. Consume much less power and cheaper.Back to contents
2: Adjustment of worm gear and gearbox
After disassemble it I start looking after what cause the heavy backslash and if there are some parts that can be adjusted.
The adjust hex screw (10:a) for the alignment of worm gear. It was totally out of adjustment.
Here I found a second adjustment screw (11:a) for the worm gear. After adjusting this I reduced the backslash to almost nothing in the worm gear.
I found more backslash in the gearbox, and one of the gears was loose. It was possible to tighten the gear to the shaft. And with adjusting (12:a) the position of the motor the backslash was reduced, but not perfect. There is also one more screw to adjust, that one I couldn't reach, I will do it later.
Even the holder for the camera has a worm gear built in, with the knob (13:a) to the right it's possible to adjust camera angle.Back to contents
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3: Will it work after this repair and adjustment?
It looks like the gearbox works now and it's much quieter, but the LEDs flashes, maybe an indication of too heavy load or too stiff gearbox. I have to adjust it one more time and also take apart the gearbox to see if some of the shafts are bent.
I will do a test as it is now, among test that's important to do is to let the RA axis do one complete revolution to see that it don't get stuck at some position. From this I will get more experience of what can be wrong.
If I understand it right the batteries in the mount will last up to 40 hours, the camera (Canon EOS 6D) battery will last 4 to 6 hours.
4: Complement with a tripod
The Star Adventure needs a steady tripod, more than a normal tripod for photo.
Luckily my friend Robert had an steady tripod that I could borrow.
I had to tighten the friction screws to the hinges. The head of the tripod has a bolt to attach it to the instrument.
The bolts diameter is too far big for the Star Adventure. I don't want to destroy anything on the tripod, I have too replace it with a 3/8" bolt.
Here is the new 3/8" bolt with it's washer.
Here how it looks with the Star Adventure, Canon 6D camera and Sigma 150mm f2.8 lens attached. The tripod is very steady and light weight.Back to contents
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5: Complement with a light weight holder
Sometimes when I travel I could not bring with me the big tripod. Then I have this solution:
I don't think this will work with my 150mm f2.8 lens, but with shorter lenses. Now I can bring with me this as a hand luggage on flights.Back to contents
6: Polar Align
Now at end of the summer it has come darker again at the nights and I can do outdoor test again. But I have to solve one problem, normally I always do the polar align with the drift align method with help of the auto guider. With this mount which doesn't have a auto guider I must do it an another way, the mount has a built in polar finder scope with a reticle screen. I just have to know where to put the polar star, it will change with time and place, I need the hour angle.
I found these two very handy apps to my Android telephone that can give me that information:
Simple Astronomy Tools
The second one also have some other tools. I will write later how successful this was when I have tried it out with my 150mm lens.Back to contents
7: Travel kit
Here is a photo of what I bring with me with the big travel kit to my Star Adventurer:
Here is a photo of what I bring with me with the small travel kit to my Star Adventurer:
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8: Dithering ?
One thing that I really missing is that I can't do dithering. But maybe at last there is a solution to it. I asked the Ivo, the developer of APT, the camera control program. He maybe think it could be done.
The solution should be here, I think it's done through the ST4 connector, just have to figure it out:
Configure APT to do dithering
The Star Adventurer can be auto guided through ST4 and it must have something to do with that, but there is to much other things for me to do for the moment.
See my first photo with with this mount and a Sigma APO 150mm f2.8
9: Red Dot Finder
One thing I noticed now when I have started to use my Star Adventurer, it's very difficult to aim to the object with a 150 mm lens. With my EQ6 mount and computer control I don't have to think about it. But here it's a problem. I got an idea from a person at the Swedish forum Astronet, he told me to try a Red Dot Finder.
Here you find Astronet, sorry, only in Swedish:
They have Red Dot Finders at Stjärnhuset in Sweden. There are many different models and I choose the model with a Hot Shoe Holder, with that I can mount it direct on the camera. Maybe I don't get the highest precision, but enough.
Stjärnhuset (Starhouse), sorry, only in Swedish:
I ordered one and got it a few days later, just about 13 Euro + shipping cost, look under AstroBoot at Stjärnhuset.
Here how it looks mounted on my DSLR camera. I have never used such a device before so I don't know what to expect from it. But looks nice and it's easy to mount on the camera. No weight to mention and that's good when I use my portable mount.
Here is the Hot Shoe Holder, maybe a little bit weak. When you tighten the screw it bends the aluminium frame. But not very big problem, you will learn to use the same force to always get it in correct position, or you can build a new holder from an old flashlight. The screw is made of plastic to not scratch the camera hot shoe. You can of course also take away the hot shoe holder and mount it direct on your mount to get better precision.
There is a builtin adjustment of the horizontal and vertical position.
On backside there is a switch. It has off, low and a high position for the red LED. When I first started it there where no light, just some oxidation on the battery, just rotate the battery and then it work.
Now I'm very exited to test this new toy!Back to contents