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Old 04-05-2010, 07:36 PM
TrevorW
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Focusing for HA

When using a HA filter do you focus as normal first then attach the filter or focus with the filter in place

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Old 04-05-2010, 07:44 PM
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dugnsuz (Doug)
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Pasting this from a recent post of mine...

Ha isn't the easiest on a DSLR that's for sure - checking focus between each shot in the absence of a bright star in the FOV is going to be a nachtmare!!!!http://www.iceinspace.com.au/forum/....milies/lol.gif
I developed a little routine to help with the "user" program of Synscan which makes life a tad easier (just a tad mind!!) Find a bright star without Ha filter - set it as user object 1. GoTo and Frame the object you want to image - set it as user object 2. Go back to obj 1 (bright star), insert Ha filter into imaging train, focus, slew back to obj 2 - start imaging!!!! Simple Eh!?http://www.iceinspace.com.au/forum/..../rolleye09.gif
(I'm using EOS clip in filters on my 40D Trevor)
The bugger is that if you use this to method to focus in-between shots, you stuff around with the guiding a bit too much.
Doug
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Old 04-05-2010, 07:59 PM
TrevorW
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Thanks Dougie yeah I thought I'd have to focus is place maybe try with a Bahitov on a bright star
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Old 05-05-2010, 09:30 PM
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Tandum (Robin)
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Trevor, Just put the filter in and plonk the mask on the front of the scope and up binning to 2x. Draw a box around the brightest star in the image and get a sub image and then increase exposure time till you see the lines from the mask. Now focus.
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Old 05-05-2010, 10:43 PM
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dugnsuz (Doug)
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Quote:
Originally Posted by Tandum View Post
Trevor, Just put the filter in and plonk the mask on the front of the scope and up binning to 2x. Draw a box around the brightest star in the image and get a sub image and then increase exposure time till you see the lines from the mask. Now focus.
Another reason to dump the DSLR - D'Oh!!!!
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Old 05-05-2010, 10:50 PM
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Tandum (Robin)
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To be honest doug the mask lines are better defined in 1X and blocky as hell in 4x but getting a sub image with longer exposures is the key and you can do that with a dslr and the right software
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Old 06-05-2010, 03:55 PM
TrevorW
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Thanks Robin didn't increase the binning but just did a longer exposure
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