About two weeks ago I finally got my hands on the motor drive for my Astromaster 114EQ. I was debating whether I really need it or not and finally decided to just go for it. And over the weekend I had it installed and tested.
To start off with, the motor drive arrived with minimal instructions. But that wasn't really a problem. The product was quite well made that I was quite intrigued by the whole design. Granted, it wasn't very intuitive, but the instruction sheet was quite to the point, that it was quite impossible to screw it up. It even had an Allen key and a screwdriver that fits the relevant bolts.
But this doesn't mean that everything was going smooth. Once I fitted the mounting bracket, I figured that the coupler between the motor and the scope wouldn't fit on to the RA shaft (Celestron refers to this as the flexible coupler). The inner diameter of the coupler is almost exactly the same size as the shaft. I was about to file it off when I figured that I had a smaller Allen key that would allow me to take the coupler and the motor axis apart. When I took it off, just for the sake of curiosity, I reversed the coupler (i.e. fixed the motor axis with the end that is supposed to be on the RA shaft) and tried. Well guess what? It worked! For the sake of confirming, I dropped a mail to Celestron and well they replied with the following:
That sorted, I decided to test out the whole apparatus. Motor tracking of a telescope that is on an equatorial mount requires careful alignment with the North-South axis and speed setting. Screw up one thing and then you are done. The easiest method of polar alignment is to point the telescope at Polaris. Given that Sri Lanka is 5-60 degrees above the equator, this means that Polaris appears just 5-60 degrees above the northern horizon. Not possible to aim at it for all practical cases.
So to end a long story, I managed to polar align the telescope using the compass on my phone. Given the really bad weather, I decided to first try out tracking the sun. Didn't expect it to work much, but after twiddling with the speed regulators a bit, managed to keep the view reasonably within the field of the camera. Following are snapshots 1 min apart from a movie shot through the Astromaster 114EQ with a 550D attached to it on a prime focus (the reason why it is out of center in the first frame it self is because I knocked the telescope trying to shoot).
Usually the disc of the sun manages to go through a screen of 3400+ pixels in the matter of seconds. In the frames above, the disc stays contained in a screen of 320 pixels for nearly 5 mins. That's pretty good.
Given that there is a drift, it still means that you can't take exposures that runs in to multiple minutes. But there is no need to do that. Going unguided, an exposure of 30 seconds shows reasonable star trails. Some of the photos I took of the Milkyway was limited to multiple shots of 10second exposures. But there is stacking. You stack 10 frames of 10 second exposures, that covers an equivalent exposure of 100 seconds. I reckon that now I can go for exposures up to 30 seconds without getting any trails.
More than the exposure, what I wanted was to get to a set up where I can shoot 10 second exposures over a prolonged period. If I had an unguided camera, I would have to realign the set up every half an hour or so. But with this set up, I can pretty much shoot few hours and let DSS handle the aligning part.
One problem with this is that you would have to decouple the motor if you want to control the RA manually. You can keep the RA manual adjuster fixed to the other side of the shaft even when you have the motor on (and I keep it so that I can see the motor working), but if you try to adjust it manually while connected to the motor, then the reverse current could damage the motor. Usually you don't need to adjust the RA shaft it self, but some times I decide to go crazy and use the equatorial mount as an almost-dobsonian mount :)
So that's all for now. Orionids are coming up in about two weeks and hopefully I'd be able to use the guided equipment for a good set of photos.
To start off with, the motor drive arrived with minimal instructions. But that wasn't really a problem. The product was quite well made that I was quite intrigued by the whole design. Granted, it wasn't very intuitive, but the instruction sheet was quite to the point, that it was quite impossible to screw it up. It even had an Allen key and a screwdriver that fits the relevant bolts.
But this doesn't mean that everything was going smooth. Once I fitted the mounting bracket, I figured that the coupler between the motor and the scope wouldn't fit on to the RA shaft (Celestron refers to this as the flexible coupler). The inner diameter of the coupler is almost exactly the same size as the shaft. I was about to file it off when I figured that I had a smaller Allen key that would allow me to take the coupler and the motor axis apart. When I took it off, just for the sake of curiosity, I reversed the coupler (i.e. fixed the motor axis with the end that is supposed to be on the RA shaft) and tried. Well guess what? It worked! For the sake of confirming, I dropped a mail to Celestron and well they replied with the following:
Dear Kulendra ,Well guess I got it right.
Thank you for contacting Celestron Technical Services. The flexible motor coupler housing is too small to go into the shaft. Please turn the coupler the opposite way so that it will fit in the shaft.
Thank you,
Celestron Tech Support
That sorted, I decided to test out the whole apparatus. Motor tracking of a telescope that is on an equatorial mount requires careful alignment with the North-South axis and speed setting. Screw up one thing and then you are done. The easiest method of polar alignment is to point the telescope at Polaris. Given that Sri Lanka is 5-60 degrees above the equator, this means that Polaris appears just 5-60 degrees above the northern horizon. Not possible to aim at it for all practical cases.
So to end a long story, I managed to polar align the telescope using the compass on my phone. Given the really bad weather, I decided to first try out tracking the sun. Didn't expect it to work much, but after twiddling with the speed regulators a bit, managed to keep the view reasonably within the field of the camera. Following are snapshots 1 min apart from a movie shot through the Astromaster 114EQ with a 550D attached to it on a prime focus (the reason why it is out of center in the first frame it self is because I knocked the telescope trying to shoot).
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| Start | 1 min | 2 min | 3 min | 4 min | 5 min |
Usually the disc of the sun manages to go through a screen of 3400+ pixels in the matter of seconds. In the frames above, the disc stays contained in a screen of 320 pixels for nearly 5 mins. That's pretty good.
Given that there is a drift, it still means that you can't take exposures that runs in to multiple minutes. But there is no need to do that. Going unguided, an exposure of 30 seconds shows reasonable star trails. Some of the photos I took of the Milkyway was limited to multiple shots of 10second exposures. But there is stacking. You stack 10 frames of 10 second exposures, that covers an equivalent exposure of 100 seconds. I reckon that now I can go for exposures up to 30 seconds without getting any trails.
More than the exposure, what I wanted was to get to a set up where I can shoot 10 second exposures over a prolonged period. If I had an unguided camera, I would have to realign the set up every half an hour or so. But with this set up, I can pretty much shoot few hours and let DSS handle the aligning part.
One problem with this is that you would have to decouple the motor if you want to control the RA manually. You can keep the RA manual adjuster fixed to the other side of the shaft even when you have the motor on (and I keep it so that I can see the motor working), but if you try to adjust it manually while connected to the motor, then the reverse current could damage the motor. Usually you don't need to adjust the RA shaft it self, but some times I decide to go crazy and use the equatorial mount as an almost-dobsonian mount :)
So that's all for now. Orionids are coming up in about two weeks and hopefully I'd be able to use the guided equipment for a good set of photos.
I am plannign to buy Celestron Astromaster 130 AZ Telescope
ReplyDeletehere is the specs suggest me good one
Newtonian Reflector
130 mm (5.12 in)
650 mm (26 in)
f/5
20 mm (0.79 in)
33 x
10 mm (0.39 in)
2 65 x
Built-on StarPointer
307 x
19 x
13.1
1.07 arc seconds
0.89 arc seconds
(Compared to human eye) 345 x
Celestron Astro Master 130.