ICEINSPACE
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01-03-2011, 06:44 PM
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ze frogginator
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Join Date: Oct 2007
Location: Sydney
Posts: 22,068
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Yes - I was thinking the same thing. I pause guiding between subs. I always do dithering this way. Rotational (poor PA) or Translation (poor balance)
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01-03-2011, 06:53 PM
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Retired, damn no pension
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Join Date: Nov 2004
Location: Obi Obi, Qld
Posts: 18,778
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There is definitely flexure in there Fred as I was loosing images because of it. But even when the stars are beautifully round there is still movement between the images.
After changing a few things around last night (screw in attachment, shorter subs) I managed to get more keepers than throwers (20 / 20 in fact ) but still had the creep across the page.
Its just strange that I very rarely had this with the G11, but then I wasn't imaging at 2000mm focal length then.
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01-03-2011, 07:06 PM
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Narrowfield rules!
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Join Date: Nov 2006
Location: Torquay
Posts: 5,065
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Quote:
Originally Posted by [1ponders]
But even when the stars are beautifully round there is still movement between the images.
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Well then, what were the sub exposure times and what was the time between exposures?.
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01-03-2011, 07:13 PM
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Retired, damn no pension
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Join Date: Nov 2004
Location: Obi Obi, Qld
Posts: 18,778
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sub exp were 5 min and the time between exposures 5 sec
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01-03-2011, 07:26 PM
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Registered User
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Join Date: Oct 2004
Location: New Zealand
Posts: 4,345
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I'm with Fred, if your 5 minute shots are round, then this isn't flexure to me. You haven't requested dithering have you, inadvertently, somewhere in that new Maxim 5?
Does this happen if you capture with other programs, Nebulosity and PHD?
Does it happen if you use the SX?
Gary
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01-03-2011, 07:50 PM
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Narrowfield rules!
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Join Date: Nov 2006
Location: Torquay
Posts: 5,065
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Quote:
Originally Posted by gbeal
if your 5 minute shots are round, then this isn't flexure to me. You haven't requested dithering have you, inadvertently, somewhere in that new Maxim 5?
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Exactly
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01-03-2011, 07:50 PM
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Mostly harmless...
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Join Date: Jul 2008
Location: Brisbane, Australia
Posts: 5,735
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I think its got to be the mount Paul. I'll bring up my Heq5 to swap yours out for a while and try to sort it out on the AP from here.....
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01-03-2011, 07:53 PM
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Retired, damn no pension
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Join Date: Nov 2004
Location: Obi Obi, Qld
Posts: 18,778
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Lol cheers thanks rob, I'd rrreeeaaallly appreciate that lol
Nope no dithering turned on
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01-03-2011, 07:54 PM
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Narrowfield rules!
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Join Date: Nov 2006
Location: Torquay
Posts: 5,065
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Quote:
Originally Posted by [1ponders]
There is definitely flexure in there Fred as I was loosing images because of it. .
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Definitely no. more likely awefull PE, or a mechanical problem (for loss of images that is). Flex doesnt cause sudden loss of guideing
Last edited by Bassnut; 01-03-2011 at 08:15 PM.
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01-03-2011, 08:11 PM
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Retired, damn no pension
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Join Date: Nov 2004
Location: Obi Obi, Qld
Posts: 18,778
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the elongation with the stars varies in direction Fred, sometimes Dec, sometimes RA sometimes both. The movement movement between frames though is fairly consistent in its direction.
What i might do is put together an animation over a few hours, including bad frames and see what come up.
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02-03-2011, 06:31 AM
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Registered User
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Join Date: Oct 2004
Location: New Zealand
Posts: 4,345
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Any capture program, and any imaging camera? Or just this program, and that camera?
If it is all over the place, I keep harping back to something like dithering?
Gary
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02-03-2011, 07:39 AM
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Retired, damn no pension
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Join Date: Nov 2004
Location: Obi Obi, Qld
Posts: 18,778
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It does it in both Ver of Maxim I have, I've not tried any other. Not sure about the camera. Though it doesn't appear that the guide camera star moves, just the image received from the SX
I noticed last night that when shooting ngc2442 that the drift was almost parallel to the Dec. Next clear night I will spend the night taking 6 / 5 min shots from all around the sky and see if there is any sort of pattern to the direction of the drift.
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02-03-2011, 02:39 PM
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Registered User
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Join Date: Mar 2009
Location: melbourne
Posts: 287
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I do find similar symptom when guiding through a seperate scope. following link might help answering some of the questions http://www.stark-labs.com/blog/files/tag-flex.php
I don't think its possible to zero out the flex, but definetely you can improve on it. Once you have done all the things that you possibly can do to reduce flex, Knowing how long you can expose before the error creeps up in the subs will be the key.
Regards
Sad
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02-03-2011, 04:19 PM
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Retired, damn no pension
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Join Date: Nov 2004
Location: Obi Obi, Qld
Posts: 18,778
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thanks for that Sad. That will give me something to work with. I'm going to spend some time this weekend going over everything on the rig and eliminate or tighten if i can't eliminate everything that could be causing flex (like switching back to a star diagonal) and then start taking some measurements. Cheers
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02-03-2011, 05:36 PM
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Registered User
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Join Date: Oct 2004
Location: New Zealand
Posts: 4,345
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OK, since you have my pea sized brain going, why not try the SBIG with Maxim (you still have it??).
Then also try PHD/Nebulosity with the SX.
Gary
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02-03-2011, 05:43 PM
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Retired, damn no pension
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Join Date: Nov 2004
Location: Obi Obi, Qld
Posts: 18,778
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thanks Gary, all part of my cunning plan
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02-03-2011, 05:49 PM
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Registered User
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Join Date: Oct 2004
Location: New Zealand
Posts: 4,345
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What to get the pea sized brain going, or to exhaust all possibilities?
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02-03-2011, 06:12 PM
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Retired, damn no pension
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Join Date: Nov 2004
Location: Obi Obi, Qld
Posts: 18,778
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I'll pop the ST-7 on the VC200 and self guide and use that as my control.
I also plan to take the WO 72 out of the equation (might be movement in the focuser) and using the much lighter SV50 both on top and SBS. I've also got other programs available to try as well. CCDSoft can operate the SX as well now (though not ideal). I also haven't been able to get the little EXView to work yet with Maxim. I'll work on that as well. All I need are some clear nights.
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02-03-2011, 06:16 PM
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Registered User
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Join Date: Oct 2004
Location: New Zealand
Posts: 4,345
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Good plan, keep us in the loop.
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02-03-2011, 07:05 PM
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Registered User
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Join Date: Oct 2005
Location: Junortoun Vic
Posts: 8,917
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Paul,
Also record the time and the Hour angle of the object....you'll be able to see if gravity is your friend....
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