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How many of you "Drift Align


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Hi Guys

This is something i have never actually done icon_scratch.gif

I seem to rely on trying to get polar alignment as accurate as i can.

Unfortunately i have not got a "guided steup" so i am restricted to maximum 90 secs subs when i image at prime focus through my 250PX with my canon 350D.

I generally have to delete 35% of my subs due to star trailing.

This of course is variable depending on the targets nearness to the pole star.

In your opinion , would drift aligning enable me to maybe take longer subs with less of a % deletion of subs?

Look forward to comments on this one.

thanks

Graham

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I mentioned "drift alignment" to someone a few weeks ago and got these strange looks...what about a polar alignment telescope??? Not necessary...in fact I've never actually used one!!;)

It suddenly dawned on me... I've been in the southern hemisphere for the last forty years (South Africa/ Australia) where there is NO polar star. (Sigma Octans is a faint obscure star at the best of times) So most, I'd say 99%, of amateurs south of the Equator do drift alignment.

For over 15 years I did a LOT of astrophotographic work; we has a few prefered dark sites and we used to take it for granted that we would be drift aligning...it becomes second nature...easy and very accurate.:)

Just my 2c

Ken

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I do it even though observatory based. (Once a year or so.) It just refines your polarscope alignment and can be very quick. My preferred crib sheet is the one by Ian King on his website, Ian King Imaging.

Olly

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i also don't drift align except once a while. since i am also a beginner at DSO photography my first photos are not above 3 mins and sometimes in that time i also have drift. i asked about the problem i had and they advised me to check the balance of my telescope. Make sure you have a very good balance at your telescope. place all the equipment you use during photography along with cables etc and balance it, then check the balance of your telescope at home position. if it moves from that position rotate your telescope so that the camera, the focuser etc. face towards the inside of your mount (towards the weights of the mount) and check again the balance. repeat until there is no rotation. after that make sure your tube is vertical towards the ground and make sure it does not rotate again. if it does then rotate the tube. check again step 1 and repeat until there is no rotation. also make sure that the tube is balanced at vertical position at both sides of the mount. when everything is balanced you will end up with the focuser looking towards the ground at home position and the tube will be balanced at every position you place it.

also make sure there is not much weight at the front of the tube. if you have a heavy finder or a telrad remove it when you balance the telescope and use it only when you make a 3 star alignment and you want to see where the telescope looks, during photography remove the unnecessary weight.

i balanced my telescope that way and it does not move at all, unfortunately the sky got cloudy before i manage to take any photos with the new balance.

i guide with phd guiding and according to stark you don't need to have drift aligned, just make sure you have a good polar alignment.

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I drift align my mount. It is very easy once you get the hang of it, and more accurate than a polar scope.

Not only does it enable me to make very long exposure (1 hour length sometimes) subs, but it makes the goto/planetarium much more accurate too.

Cheers

TJ

I use this guide every time.

Classic Astrophotography - Photographing the Cosmos with ordinary film

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hello again. last night the clouds finally cleared and i tried the new balance setup of my scope and i was able to take 5 mins of exposure of m51. the trail still existed but it was much smaller than other times. i logged the periodic error of my mount and it is between 4.08 and -3.1 arcsecs for RA and 5.19 and -4.23 for DEC. i guess i have to dismantle my mount and grease it up.

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TJ..i assume you mean 1 hour in length "Guided";)

Yep, unguided I sometimes do for 20 mins or so, but PE shows up and messes things up, the guiding gets it back on track before it ruins the pic.

Guiding isn't the be all and end all, as if the polar alignment is out, you will still start to see errors and drift effects on long exposure shots.

For permanent setups, drift aligning is only sensible. For mobile setups with a decent polar scope, drift aligning, and then noting the position of Polaris in the polar scope may be a helpful shortcut. I used to mark the floor with the position of the legs, and the position of the mount against the tripod too.

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