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Old 29-05-2009, 10:34 AM
UK1 (Rob)
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Impossible question part 2... drift align.. driving me crazy

Thanks for all the advice guys has been very good
But I think all my dreams have come to an end
I set the scope up as I should ...all level... found true south….set up possie for...145e 37s all perfect
As I said polar align very hard very faint extra light pollution right under where it should be
You all said drift align was the way to go ..done research found stars to track ( was the pointers )
was to high they said I had to be lower around 30 deg’s ….. Just about cant see anything in the sky at that level….light….hills...trees... so very little chance of drift align so I’m now snookerd all dressed up and now where to go except ebay or selling section here look out for it, might find a bargain over $3000+ equipment not even seen a nubula or a galaxy yet let alone take photo’s.
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Old 29-05-2009, 10:43 PM
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Quark (Trevor)
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Rob settle down, remember the words in bold print on the front of "The Hitchhikers Guide to the Galaxy", "DON'T PANIC".

I don't know what research would lead you to using the pointers to star drift align your eq mount. They are to far south.

Use a star as low as you can see in the east and then a convenient star at the meridian, "that would be overhead". It is not hard AND GETS EASIER THE MORE OFTEN YOU DO IT.

Again, YOU DON'T NEED TO SEE THE REGION OF THE POLE TO POLAR ALIGN.

Sounds like you have absolutely no idea about how to do this. I know, initially it can seem insurmountable, but it is not.

Seek out your nearest astro group, club or society and I am sure you will find someone to walk you through this mini crisis.

Cheers
Trevor
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Old 30-05-2009, 07:49 AM
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sheeny (Al)
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Good advice there from Trevor (and none less than Douglas Adams!)

Rob, I'm guessing you're somewhere near Pukapunyal? As Trevor suggested it is probably a good idea to get along to a nearby astro night, or find someone on IIS who's nearby who can help.

This stuff always seems daunting at first, but it sounds like you're just missing some basics. So I'll try to explain what the basics are that I think you are missing.

When drift aligning, the stars you use need to be within say 30 degrees of the celestial equator. If you aren't sure which stars to use, a planisphere or star chart may help. I always recommend a planisphere to anyone starting in astronomy - they are cheap (about $30 say) and can show you how the sky looks on any day at any time, so they are great for learning the sky and picking out alignment stars!

You probably have done some searching and found a description of how to drift align, so I won't go into that much (let us know if you want us to! I'm making an assumption here which won't help you unless its right).

The other tip I would give you when starting to drift align, is to start with big changes (adjustments). A wise old man (who's a year younger than me) taught me that one - thanks Paul!

Once you've adjusted too far (i.e. the star is now drifting the opposite way), you know true south is in between your current alignment and the previous one. So then you start halving the difference. A practical application of binary search theory. With practice it will get you aligned in practically no time (say 30mins) but to start with expect some stuff ups and "learning experiences".

When I started I could spend all night drift aligning and then pack up in disgust. Prior to building the obs, I could drift align in less than an hour - typically 20-30 minutes for most stuff.

Its a steep learning curve. Have patience, padewan. Ask questions.



Al.
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Old 30-05-2009, 11:08 PM
Glenhuon (Bill)
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Ignore the polar scope, they are OK for the northern hemisphere, but I've found not much use over here unless youy have a clear view of the stars around the SCP.
For drift alignment all you need is an eyepiece with illuminated crosshairs and this simple guide. Since you have found true south and have the elevation set to your latitude. Easy from here. Only difference I have found is that if you are using a reflector, adjust the azimuth in the opposite direction to the instructions.

Cheers
Bill
Attached Files
File Type: pdf DRIFT ALIGNMENT[1].pdf (4.5 KB, 27 views)
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  #5  
Old 31-05-2009, 07:55 AM
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sheeny (Al)
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Quote:
Originally Posted by Glenhuon View Post
Only difference I have found is that if you are using a reflector, adjust the azimuth in the opposite direction to the instructions.
Be careful with this statement - perhaps a bit of an oversimplification, Bill. It depends on the number of reflections in the scope.

A straight through refractor (no diagonal) should be the same as a newt and a straight through cassegrain (2 reflections). A refractor with a diagonal (1 reflection) and a cassegrain with a diagonal (3 reflections) will be the same but opposite to the first lot.

However, if you start with big adjustments, you'll soon work out which way is right or wrong.

Al.
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Old 31-05-2009, 12:48 PM
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RobF (Rob)
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Heck Rob, are you sure you're not aiming too high up the learning curve at the moment? If you haven't seen any nebs at all, why don't you just play visual for a while and have some fun. You should be able to achieve at least a one star alignment with minimum fuss and use the finder to home in the rest. Drift aligning is really only necessary for serious astrophotography with exposures>1min.

IIS members can be a HUGE help flattening that learning curve, but astrophotography can be a bit like hitting your head against a brick wall sometimes - just more expensive!

Don't you dare give up on us without trying visual for a while! Failing that, stack lots of short exposures<1min for while until you get to a gathering somewhere.
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Old 31-05-2009, 02:48 PM
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leinad (Dan)
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I'm with RobF, get some basic use out of the mount. Get to know your mount and some of the stars used for alignments. Do some visual, get to know the sky.

Sometimes you'll be amazed from a simple setup(without polar aligning) how close you are to the pole.
Get to know your camera and software; take some shots <1min; get to know the sensitivity/gain or ISO settings.

Drift aligning can become all to confusing very quickly when only first starting. be patient, practice makes perfect.. and yes talking to someone in person that can assist would be ideal for first starters.

Shortly after when it's all so easy you'll wonder why you ever thought it was so hard and confusing in the first place.

a flash animation would be handy. hmmm
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