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swag72

Drift align - A quick and easy question to start

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I am going to have a go at drift alignment in a bid to sort out my stars. I am using a guide that I found on here and I have a question at stage 2!!

1. Setup and align your telescope normally.

2. Set your telescope to point due south and at 0 degrees DEC.

Telescope pointing at due South is not a problem, I take it I use the handset to move it? But how do I find 0 degrees DEC?

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Zero degrees DEC is the celestial equator.

It will be marked on whatever planetarium program you're using.

You don't need to be at exactly zero theough....a few degrees higher still works.

Rob.

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That's you telescope elevated in azimuth by an amount corresponding to your 90 - your latitude, so if you are at 50 degrees north then your telescope will need to be elevated by 40 degrees in azimuth when pointing due south. :rolleyes:

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Thanks - Got that !!

Next question. It tells me to put my star to the right of the sensor, set the camera for a 125s exposure and after 5s press the W key to move the star across to the opposite side.

I take it that is the left hand arrow on my handset? I have no W!

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From the tutorials I've seen, they start with the scope in the default home position of weights down, scope pointing towards Polaris, parallel to the RA axis. Then release the DEC clutch and rotate the tube 90 degrees so its pointing east, and then lock the clutch. The tube should then be horizontal. Then release the RA clutch and rotate the RA axis westwards so the weight bar ends up horizontal and pointing east. The scope should now be more or less pointing close to the point where the equatorial line crosses the local meridian.

Have a look at this - hope it helps Andy's Shot Glass - Drift Alignment for Amateur astrophotography,ccd, Neutonians and Refractors, amateur astronomy

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Thanks - Got that !!

Next question. It tells me to put my star to the right of the sensor, set the camera for a 125s exposure and after 5s press the W key to move the star across to the opposite side.

I take it that is the left hand arrow on my handset? I have no W!

Hope this helps

Zeroing it in. Using a DSLR or CCD to Align Your Scope.pdf

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This is the guide I am using Malcolm, that you posted above. Struggling to work out where to move the scope.

Just had a go with what I think is West and all I got is one straight line, but I am sure my DA can't be perfect already!!

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Interesting drift alignment guide, I might give that a go tonight!

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Sara, I use EQMOD, which has the buttons marked NSEW on the screen, not sure on the handset though.

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Here's the thing, I can't get my stars to move ACROSS the viewfinder, they are moving diagonally to the left. With my scope pointing at due south, approx 0 degree dec, my 4 handset buttons are basically going to the four corners - How do I know which is west?

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My trails are also at an angle - could be the camera position ?

Yeah, on this one I got the timing wrong :rolleyes:

post-23388-133877651334_thumb.jpg

Edited by malc-c

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Put your scope on a fast slew rate (x64 or above), and try the buttons.

You'll see instntly which is NSE or W.

You could mark them then for future reference.

Rob.

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Thanks Rob - Good idea - I've done that against Stellarium. So I now seem to have a NSEW, totally in different directions to the camera sensor, but then I guess that is easily moved.

So, now I know NSEW, do I move the W as stated, but rotate my camera so that it is going from right to left as now it's going up and down!!

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I am VERY surprised to say that I only needed the slightest tweak looking south and nothing required looking east. Either I have done something wrong, or my PA etc is perfect!!

Just having a little go to see if it has made any difference with the stars.

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I have used the same method and it is much better than any of the software mentioned on this forum. Software is ok but with this you get a feel for how far its out and it takes a mere two minutes to recheck.

Have a play and misalign one of the axis and do the drift align. You can then get a feel for how much readjustment, and in which direction, is required depending on the difference in position of your start finish position.

You may have been accidently moving the Ra if you got a straight line....or the alignment is good!

Also be very carefull on star choices, some stars will not give a good drift alignment due to their position...cant remember why though..may be confusing it with the iterative method.

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Sara

My only thought is the comment at the end of the article; I think the HEQ5 is a GEM mount, but not sure what the "different corrections" are.

"(Note: This method was used with a fork mounted telescope. Those who use a GEM must make different corrections, however this method will work with them as well and will increase their accuracy just the same.)"

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First you need to get the camera square on to RA and DEC simply by rotating it. To see where it is at any one time do a three second sub while slewing and look at the orientation of the trails. I try to image 'N is up' when possible so my camera is usually in the right place.

To find out which button does what on the handset, just point the scope in roughly the right direction and on the side of the mount you'll be using for drift alignment. Set a fast slew and watch which direction it goes in when you press the buttons. Write them down if you are anything like me!!

I like the look of this method. I know it says it was done on a fork but all that matters is that you end up with a straight line 'out and back' star trail so experiment accordingly with adjustments. (I say this without having tried it yet...)

Olly

Edited by ollypenrice

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Didn't manage to get a sub to look at last night as I'd removed the clip filter for this and frankly couldn't be bothered to put it in a refocus!! (It was late is my excuse!!)

So I look forward to having a go this evening and seeing if the stars are nice and round.

I have taken the guider cables out of the tidy and taped them to the OTA. The finder bracket is absolutely solid - Nothing much else to try if the problem persists!!

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I did it on an eq6, you dont need to align or rotate the camera (it is not essential). You can turn off tracking to see the orientation of the ra axis whilst taking a sub.

You then do the 125 s sub and see if you get a straight line or two lines indicating an error in alignment. The distance between start and end points will give you an indication as to how far out. Have a play and see how far out one turn of the ra screw puts it etc. (or dec if you fancy..)

I am sure camera alignment helps with guiding but with this dont over complicate keep it simple.

Edited by ncjunk

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Bump

Question for those who have used DARV.

when selecting a star should it be average brightness one ? just i tried this the other night and i used Sirius. now the line looked very much that it had overlapped but it occured to me later that as it was so bright that maybe the two lines and just blurred together.

or should i turn the iso setting right down ?

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I have performed drift alignment visually (ie not with a camera) fairly successfully after reading an article. It said that when doing the altitude adjustment using a star near to the eastern horizon you need to stand to the SOUTH of the 'scope but didn't say why. Anyone know?

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