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Old 12-11-2009, 08:39 AM
Chris Southby (Chris)
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Tips on Polar alingment without a reticle eyepiece

Hi all
I am trying to get the best astro-photos with a very limited budget.

1.) I am trying to polar align my EQ5 Goto and I dont have a reticle eyepiece. I have got it fairly close buy placing the a star on the edge of the field of view at about 160x and watch where it moves and adust accordingly. Then using my 350D on 1 min exposures and looking for the length of the star trails and doing finer adjustments. I can sometimes get round almost round stars at 1 minute exposure times but no longer than that.
Does any one have any more tips on getting alignment perfect?

2.) To give me a somthing to aim for, what would be the maximium exposure time I could expect on an Eq5 without guiding for round stars with perfect polar alignment?
One further question

3.) Where can I get adapters to fit a 2 inch filter to the front of a 52mm and/or 58mm camera lens for widefield photography.

I'm hooked on this hobby and want to get the best images with what I have or can make up myself.

Cheers

Chris

3.)
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Old 12-11-2009, 05:12 PM
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bmitchell82 (Brendan)
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your in for a hard time bud! all the easy methods i know use a goto system. does your EQ5 have a polar scope? if so then use it as it will give you the best ability to polar align. other than that using your dslr take a 1 min exp and slowly move the star one way for 30 seconds and then back the other way for 30 seconds, use this to hone in untill you have 1 line not a v line. tell us how you go.

I too am a uni student on a mega budget, though i saved for the EQ6 Pro.
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Old 12-11-2009, 05:47 PM
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asimov (John)
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I've gone 2 minutes with an F4 8" newt + DSLR mounted on a eq5 WITHOUT goto or a reticle, so it can be done. Just centered the star & kept adjusting until it stayed central for 5 mins. (used a 5mm EP barlowed 2X)
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Old 12-11-2009, 07:18 PM
Chris Southby (Chris)
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I have a polar scope on the EQ5 but trees obscure the view south making that not a great option. I have goto though what is that method?

Thanks
Chris
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Old 12-11-2009, 09:11 PM
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troypiggo (Troy)
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Do you have a guidecam/webcam?
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Old 13-11-2009, 08:32 AM
Chris Southby (Chris)
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No I dont even have a laptop so its pretty much all manual control apart from the Goto. Its astrophotography on a budget.

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Originally Posted by troypiggo View Post
Do you have a guidecam/webcam?
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Old 13-11-2009, 10:24 AM
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madwayne (Wayne)
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Quote:
Originally Posted by Chris Southby View Post
No I dont even have a laptop so its pretty much all manual control apart from the Goto. Its astrophotography on a budget.
It sure sounds like it Chris , but here goes with a procedure that can at least confirm your polar alignment.

Aim your scope at a brightish star around 25 degrees above the horizon in the East or West on the Celestial equator (zero dec). With your slew speed set as slow as you can get it start a 65 second exposure (obviously in bulb mode on your DSLR). Pause for 5 seconds before slewing left for a count of 30 and then slew right for a count of 30. You will more than likely have a "V" shape with a bright star (this is your reference point), unless you have jagged your polar alignment in which case it will be a flat line. Make a mental note of where the bright star is, above or below the return line. You want to make the V a flat line. Make a big adjustment on your dec axis (leave RA alone I'll get to that shortly) and repeat the procedure until you have a flat line. The reason behind making a mental note is because if your bright star was above the return line and now it is below you have adjusted the right way but just gone too far, if the gap has widened obviously you are going the wrong way. Once you have a flat line for a 65 second count repeat it but this time go a minute or two in either direction with your 5 second pause at the start. The longer you go with a flat line the better your alignment is.

To adjust your RA axis repeat the procedure above except this time slew your scope to a brightish star on the Celestial Equator near the meridian and repeat all the steps. Of course this time you are adjusting in RA and leaving the dec axis alone.

Once you have your RA axis dialled in it would be a good idea to just drop back down again and check your dec axis. Just as you would if you are using a reticle.

You will also need to remember which knob you have tightened on both the RA and dec axis so you know whether to keep tightening North or start tightening South etc.

No guarentees that this will get you perfectly polar aligned but it will be a start.

Save those pennies and get the reticle and then keep saving for that laptop and then there is the mount upgrade and then there is aperture fever then you will want that cooled one shot color camera then you will want that premium mono cooled camera like the SBIG STL11000 and a full set of color and narrow band filters and then you will need an observatory and then finally a property with dark skies to put it on. And all of that without even shopping around for a Tak .

Good luck with it all and I hope my contribution above is of help to you.

Wayne
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Old 13-11-2009, 10:24 AM
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Moon (James)
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keep at it

Chris,

By doing it the manual way, you are really going to learn a lot. When you get some cash, a reticle eyepiece would be a good start. Andrews have them for $79 or perhaps some kind person here can find you a cheap second hand one.

1.) Not without spending more money.
The more time you monitor the drift - and the higher power the eyepiece, the better your alignment will be.
You can also try the method mentioned above - to use the camera and move the mount while taking exposures.

2.) Depends on the focal length of the scope/camera. 30 sec should be possible. How far beyond that? Well you just need to keep trying and seeing how far you can push it. 2 minutes would be impressive!

3.) What sort of filter? What's it for?

The main thing is to have fun and to start with the easy (bright) targets like the Moon, and Orion etc.

James
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Old 13-11-2009, 04:04 PM
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bmitchell82 (Brendan)
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if you have goto, get your mount as true south as you can get, slew to a star near the SCP. don't use the hand paddle just manually man handel the mount left right up and down till you get your star in the middle of the EP, you will be close enough to the SCP at the end of that sequence. if you want to go further then you have to use your camera.

to utilize technology you really need a secondary CCD and a guide scope. then you can open your mount up!
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Old 13-11-2009, 06:16 PM
Chris Southby (Chris)
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Thanks for all the tips I will be giving them a go and will report back on my progress hopefully with some nice images.


Cheers

Chris
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