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Nils_Lars
Post Laureate
Reged: 01/04/08
Posts: 3385
Loc: Santa Cruz Mountains , CA
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OK so I cant seem to just leave my set up alone without messing with some setting or another constantly.
I had my rig all dialed in last time I was out and then for some reason this time out my PHD guide will send the Dec line of the graph off the chart every 3-4 minutes which is an indicator that I just ruined my shot.
I spent a rather frustrating night last night battling software and then drift alignment to then try and try changing all the settings in PHD guide to get this fixed.
After trying a bunch of configurations I turned on resist switching in Dec and that stopped the weird jump of the graph but then my Dec line was up and down and up and down.
Out of the 8 hours I was at the dark sky site on Saturday I got less then 2 hours of data  Its all part of the hobby but its been a while since I had one this bad.
Ok so I was hoping to get some input as to settings you all are using for your PHD guide.
This is with the C8 imaging with the .63 FR and the ED80 as the guide scope but soon I will be doing the opposite for some of the wider targets.
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Erik
Orion Atlas Self Hypertuned (EQMOD)
Orion ED 80
Williams Optics VII reducer
Celestron 8" SCT
Orion Starshoot Autoguider
PHD guide
Canon 400D Hap Griffin Mod w/Baader filter
Astronomik clip-in LP filter and 12nm Ha
Stilleto CVF and Bahtinov mask
Tamron 75-300mm&28-80mm lenses
NexImage webcam
http://www.flickr.com/photos/31986095@N05/
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zAmbonii
scholastic sledgehammer
Reged: 01/19/08
Posts: 833
Loc: Ypsilanti, MI
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I gave up on trying to use the lowpass filter setting on phd. I'm not sure what gives, but I really think that works if you 1) have a really good drift alignment and 2) your dec drive has little to no backlash.
I have a feeling what may be happening for you is that there is a zone in the gear where it doesnt move that much for an input...but then it kicks it in sending your guidestar way off. This is magnified because of the lowpass stuff because it tries to smooth out the position graph.....and tends to overshoot things when the star starts to move to the 0 position.
Try to get things working well with the "resist switching", and forget about the lowpass setting. For DEC, there really isnt much you can tweak to calm down the DEC stuff....you need to get rid of as much backlash in your gears to help guide better. Remember, most of the settings in PHD guiding is for RA only....the agressiveness/hysteria is only for RA. If you mount has any type of backlash settings tweak those to make sure you take up slack in your gear without having the graph jump on way or another. On my ASGT mount, I had bring mine down to 08/08 for positive/negative, anything more will show a jump when it switches north/south.
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Check out my Astrophotos on Flickr
C6-N 150mm f/5 Newtonian
CG-5 ASGT mount
Canon 300D self modded + IDAS LPS-P2 FF
Meade 70AZ + Meade DSI for autoguiding
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buc240
sage
Reged: 02/22/08
Posts: 233
Loc: Burlington county, NJ
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It sounds like either your dec balance is a little off, but if you've been using the same rig for a while you've probably checked this, the other likley cause is your dec has developed a bit of play which is common in these mounts, when you calibrate how many steps does phd go through attempting to clear backlash? Ideally it should clear in 2 to 3 steps and begin N cal. try adjusting your dec's worm end play, and adjusting the worm mesh that should take care of it I have been working on a write up for this procedure which on the Atlas is not very difficult, I will try and get it together and post it for you
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clear skies,
Jason
www.eastcoastastro.com
SV80S/SV80 Aplanat
Atlas EQ-G
S-modified-TEC cooled 350XT
/Stock 400XTi/DSI/SPC900NC
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Nils_Lars
Post Laureate
Reged: 01/04/08
Posts: 3385
Loc: Santa Cruz Mountains , CA
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Thanks for the suggestions guys , I am going to have to go back and see how many steps were in the backlash clear since I dont remember.
Keep me posted if you get that write up done Jason I would be interested in that and im sure others would even without this problem.
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Erik
Orion Atlas Self Hypertuned (EQMOD)
Orion ED 80
Williams Optics VII reducer
Celestron 8" SCT
Orion Starshoot Autoguider
PHD guide
Canon 400D Hap Griffin Mod w/Baader filter
Astronomik clip-in LP filter and 12nm Ha
Stilleto CVF and Bahtinov mask
Tamron 75-300mm&28-80mm lenses
NexImage webcam
http://www.flickr.com/photos/31986095@N05/
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Gregk
Pooh-Bah
Reged: 11/19/06
Posts: 1450
Loc: Gilbert Arizona
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Also Make sure everything is tight I recently found my main cell on my guide scope was loose and before that my focuser ring was loose and before that I had a small bolt come loose
where the top scope rail tightens to the ring..Sounds more preiodic for you however Balance is also key as emntioned.
a littel dec heavy can help
Best of luck
Greg
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www.azspaceblog.com/
Orion Star Shoot Pro OSC
Oiron Star Shoot II OSC
Celestron Cg-5 ASGT mount
Celestron ED80 Piggy back with william Optics 66mm APO
Celestron 6" SCT Piggy Back with william Optics 66mm APO
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buc240
sage
Reged: 02/22/08
Posts: 233
Loc: Burlington county, NJ
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Erik I should have noted that the steps in backlash clearing I mentioned were based on a calibration values of 2000ms which works well for guiding with the short FL scope such as the ED80 and if you are going to reverse the scopes you can turn this value down to 500ms for guiding with the C8 here is a snapshot of my settings
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clear skies,
Jason
www.eastcoastastro.com
SV80S/SV80 Aplanat
Atlas EQ-G
S-modified-TEC cooled 350XT
/Stock 400XTi/DSI/SPC900NC
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