View Full Version here: : How do u read the scales on a eq3 mount
Phil the Sparky
03-03-2012, 06:27 PM
This may be a dumb question but I have no idea so pls be nice.
I kind of get the dec scale just not sure which way is + and which is -.
The RA scale has me stuffed I cant figure it out. All I know is it has to be set each time but I dont know how to read it to do this.:shrug:
Can someone pls point me in the right direction?
Thanks in advance for any help.
03-03-2012, 06:46 PM
Hi Phil :hi:,
Personaly I don't bother with setting circles, to hard. A telrad, well aligned scope and finder scope, good charts and lots of practice using all of the fore mentioned. Oh, a binocular helps no end in the initial finding, you would be surprised how bright the faint things are (I know, a contradiction but its true)!
I use a wide angle eyepiece (21mm at 47X for me)to find stuff then zero in with a higher magnification if required.
This method uses star hopping and it's a great way to teach yourself the night sky.
Cheers and enjoy
08-03-2012, 09:40 PM
1st polar align your scope and learn drift alignment for best results.
2nd you need to pick a bright object which you know the dec. at the time your viewing - try 'stellarium' (google this). This will tell you for eg. the RA and Dec of say Canopus.
3rd aim ya scope at Canopus (example) and set to what Stellarium tells you the Dec/RA is.
4th don't touch the setting circles as you move your scope to hunt your objects!
To state the obvious if you spend say 1hr looking for your object (I have) adjust this by adding 1hr on declination.
08-03-2012, 09:54 PM
The link with some info on "lost art" of spherical astronomy.... ;)
09-03-2012, 12:14 AM
Here's an excerpt from "Handbook for Telescope Making", published in the 60s. A quick and easy method for using setting circles. My Astro-Physics mount has large, beautifully inscribed setting circles that look terrific but but have never been used.
10-03-2012, 10:09 AM
Setting circles can be used to good effect for two things
1. Assisting in polar alignment. Set polar axis using latitude scale. Roughly point your mount south. Centre the scope(low power) on a bright star low in the sky for which you know the declination, and note the dec circle reading. If it agrees with the known value, then you are pretty close to the pole. Otherwise shift the dec axis to the correct reading (moving the star out of the field of view). Then slew the sope in azimuth until the star comes back into view. You may have to do this a few times.
2. Once you have the mount polar aligned - sufficient for visual observing, then you can use the circles in conjunction with star charts to find objects in barren areas of sky.
For example lets say you want to find M46. Centre the scope on a bright star nearby - Sirius. By reading and measuring the chart it shows that M46 is 0h 52m east and 2.4 degrees north of Sirius. Shift your scope by these amounts on the setting circles. You should see M46 in the finder, if not the main scope on low power. its easy and was the way of the world before GoTo.
Phil the Sparky
16-03-2012, 07:36 PM
Thanks for all the help. I got the free google app for the night sky which has helped so I atleast know wha Im looking at now.
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