· Get a Cloudy Nights T-Shirt · Submit a Review / Article Click here if you are having trouble logging into the forums Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User You are not logged in. [Login] Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar Equipment Discussions >> Mounts Previous   Index   Next   Threaded   Pages: 1 korborh professor emeritus Reged: 01/29/11 AP1200GTO PE curves       #5708142 - 03/02/13 03:08 AM Attachment (42 downloads) Edit   Reply   Quote Quick Reply   My AP1200GTO is now almost 2 years old. I Ran some PE curves tonight when the moon was up. Sampling at 0.48"/px using C11 EdgeHD and Atik 314L+. Seeing was less than average. First, the raw captured data before PEC. Shows a smooth and clean sine wave. Post Extras:       korborh professor emeritus Reged: 01/29/11 Re: AP1200GTO PE curves [Re: korborh]       #5708143 - 03/02/13 03:09 AM Attachment (26 downloads) Edit   Reply   Quote Quick Reply   The raw PE calculated just under 4" p-p. Post Extras:       korborh professor emeritus Reged: 01/29/11 Re: AP1200GTO PE curves [Re: korborh]       #5708144 - 03/02/13 03:09 AM Attachment (25 downloads) Edit   Reply   Quote Quick Reply   Here is the frequency spectrum of the capture. Note how large is the fundamental relative to the other frequencies indicating a nice sinusoidal and easily correctable PE. Post Extras:       korborh professor emeritus Reged: 01/29/11 Re: AP1200GTO PE curves [Re: korborh]       #5708145 - 03/02/13 03:10 AM Attachment (27 downloads) Edit   Reply   Quote Quick Reply   Data captured after uploading the measured PEC to the mount. Virtually flat line! Post Extras:       korborh professor emeritus Reged: 01/29/11 Re: AP1200GTO PE curves [Re: korborh]       #5708146 - 03/02/13 03:11 AM Attachment (22 downloads) Edit   Reply   Quote Quick Reply   The resulting PE - no period found. Good! Post Extras:       korborh professor emeritus Reged: 01/29/11 Re: AP1200GTO PE curves [Re: korborh]       #5708147 - 03/02/13 03:12 AM Attachment (17 downloads) Edit   Reply   Quote Quick Reply   Frequency spectrum - just noise. PE has been anhilated. Post Extras:       orlyandico Carpal Tunnel Reged: 08/10/09 Loc: Singapore Re: AP1200GTO PE curves [Re: korborh]       #5708191 - 03/02/13 05:02 AM Edit   Reply   Quote Quick Reply   Did you only use the fundamental for the PEM curve? On my Mach1 i use the 1, 2, and 3rd harmonics. There is still a residual of about 0.4" after PEM... Post Extras:       korborh professor emeritus Reged: 01/29/11 Re: AP1200GTO PE curves [Re: orlyandico]       #5708735 - 03/02/13 12:33 PM Attachment (13 downloads) Edit   Reply   Quote Quick Reply   I used linear fit in PemPro which selected 1,2,3 and 4 harmonics as below. You can see the 2,3,4 are insignificant. I used this default selection to program so all four were used. Post Extras:       orlyandico Carpal Tunnel Reged: 08/10/09 Loc: Singapore Re: AP1200GTO PE curves [Re: korborh]       #5708877 - 03/02/13 01:56 PM Edit   Reply   Quote Quick Reply   hmmm.. i'm always using quadratic or cubic fit. maybe i should use linear fit.. Post Extras:       korborh professor emeritus Reged: 01/29/11 Re: AP1200GTO PE curves [Re: orlyandico]       #5708913 - 03/02/13 02:22 PM Edit   Reply   Quote Quick Reply   I usually start with linear fit and check the fit quality using the RMS and scrolling through the whole data in the above dialog box. If the RMS does not change much going to quadratic, I just use linear. The quadratic fit is usually ok and may work better but higher order fitting can be artificial and not useful for smooth AP mounts. Your 0.4" corrected (after PEM) seems pretty good to me. Depending on balance and side of pier, I see somewhat different results and corrected PE of 0-0.5". Post Extras:       orlyandico Carpal Tunnel Reged: 08/10/09 Loc: Singapore Re: AP1200GTO PE curves [Re: korborh]       #5708917 - 03/02/13 02:25 PM Edit   Reply   Quote Quick Reply   i'm at 0.4" when east heavy and 0.8" west heavy. uncorrected is 3.5" east heavy and 6" west heavy. Post Extras:       korborh professor emeritus Reged: 01/29/11 Re: AP1200GTO PE curves [Re: orlyandico]       #5708944 - 03/02/13 02:47 PM Edit   Reply   Quote Quick Reply   That sounds quite good and sub-arcsec. I found it best to have it well balanced but the difference is insignificant when its all under 1". I see no difference with these PE figures with or without correction on my guided images. I usually do PE once in a while to check if nothing sudden is happening to tracking making sure mechanics of the mount are good. Post Extras:       andysea sage Reged: 09/03/10 Loc: Seattle, WA Re: AP1200GTO PE curves [Re: korborh]       #5709065 - 03/02/13 04:09 PM Edit   Reply   Quote Quick Reply   You guys! I never checked the PE on my mounts but your posts make want to dig into it. So far I just look at my subs and if they look good I don't worry:) I wonder how my 2005 vintage NJP would compare. Post Extras:       Tom and Beth Carpal Tunnel Reged: 01/08/07 Loc: Tucson, AZ Re: AP1200GTO PE curves [Re: korborh]       #5709330 - 03/02/13 06:35 PM Edit   Reply   Quote Quick Reply   Like you, I'm just starting to use PEMpro. Didn't need it when I was 100% visual, but now as I tune the mount I find visual use is even MORE enjoyable. Still have a bit more to do in order to get long exposures with a 3 Meter FL scope, Edited by Tom and Beth (03/02/13 06:36 PM) Post Extras:       Mike Clemens Frozen to Eyepiece Reged: 11/26/05 Loc: Alaska, USA Re: AP1200GTO PE curves [Re: Tom and Beth]       #5709621 - 03/02/13 09:46 PM Edit   Reply   Quote Quick Reply   PemPro fixed my AP1200 GTO right up http://www.pbase.com/mclemens1969/image/94812800 Post Extras:       korborh professor emeritus Reged: 01/29/11 Re: AP1200GTO PE curves [Re: Mike Clemens]       #5709626 - 03/02/13 09:55 PM Edit   Reply   Quote Quick Reply   That looks so much like the the PE curve on mine! Yeah the zero PE is cool. Post Extras:       andysea sage Reged: 09/03/10 Loc: Seattle, WA Re: AP1200GTO PE curves [Re: korborh]       #5709760 - 03/02/13 11:42 PM Edit   Reply   Quote Quick Reply   hmm I've been wanting to get an AP900 but looking at your results with the 1200 makes me wonder if I should shift gears and keep an eye out for a good used 1200. Post Extras:       korborh professor emeritus Reged: 01/29/11 Re: AP1200GTO PE curves [Re: andysea]       #5709769 - 03/02/13 11:50 PM Edit   Reply   Quote Quick Reply   Andysea, I would not recommend you make the choice between the 1200 and 900 based on PE. With the (not very old) AP mounts, the PE is guaranteed to be low and smooth and will <1" pp corrected out of the box. I would recommend the 1200 if you can pick and move 50lbs without issue. Its a really strong and overbuilt mount, conservatively rated for 140lb payload. They are coming up on Amart used at good prices. Post Extras:       orlyandico Carpal Tunnel Reged: 08/10/09 Loc: Singapore Re: AP1200GTO PE curves [Re: andysea]       #5709770 - 03/02/13 11:50 PM Edit   Reply   Quote Quick Reply   Andy, I don't think there's much different between the Mach1, 900, and 1200. I think it's when you get to the 1600 that you get a smaller native PE (somebody else posted about 1.6" before PEM). But these usual suspects are all in the 3.5" range before PEM. Post Extras:       andysea sage Reged: 09/03/10 Loc: Seattle, WA Re: AP1200GTO PE curves [Re: orlyandico]       #5709885 - 03/03/13 02:43 AM Edit   Reply   Quote Quick Reply   True and true! The more I think about it the more the 1200 makes sense given that I already have a 45lb. and a 70lb. mounts. I do see them come up used for very good prices. Post Extras:       Pages: 1 Previous   Index   Next   Threaded   Extra information 25 registered and 42 anonymous users are browsing this forum. 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