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DavidinFL
member
Reged: 08/28/09
Posts: 52
Loc: Navarre, FL
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Thanks for the simulations. I'm sure it's not easy to generate the pics from the little bit of info I've given.
I printed out your picture and took it to the scope for another star test. The "inside focus" once looks very close to what I saw. The "outside focus" star test was brighter around the outside ring than what is in the simulation.
I found the program FigureXP and a program for generating Couder masks. I'm not 100% sure what I'm doing but I think I have the idea. If I have it right, you put the mask on the mirror and get the pair of holes closest to the center both to the same brightness (50%). Then, record the reading on the dial indicated. Back the knife away from the mirror until the next set of holes are equal in brightness, record, and repeat?
The zone calculator recommended 3 or 4 zones. Which should I shoot for. I'm leaning towards 4 because more information is better, but I don't want to trip myself up the first time doing this
If that's correct I hope to try to take some readings tomorrow or the next day. I'll admit to feeling like I'm way behind the curve trying to pick up on all the technical aspects of mirrors, but at least it is fun!
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Orion XT8 - Orion StarMax 102 EQ
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mark cowan
Vendor (Obsidian Optics)
Reged: 06/03/05
Posts: 2159
Loc: salem, OR
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Use 4 for the 8" f/6, also look at Nils Olof Carlin's mirror zone calculator page for an intro and the math. Have fun!
Mark
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joe colontonio
sage
Reged: 03/02/06
Posts: 206
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Hey Dave, Where in florida are you at? There might be local help
Joe
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DavidinFL
member
Reged: 08/28/09
Posts: 52
Loc: Navarre, FL
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Mark: That's the calculator I'm using.
Joe: I'm in Navarre, about 20 minutes east of Pensacola.
Thanks!
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Orion XT8 - Orion StarMax 102 EQ
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joe colontonio
sage
Reged: 03/02/06
Posts: 206
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Does the Escambia {EAAA} club have an atm group. They might be able to help.
Joe
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DavidinFL
member
Reged: 08/28/09
Posts: 52
Loc: Navarre, FL
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I tried some testing with the Couder mask tonight. I appear to have no innate talent when it comes to this. I wasn't able to generate any consistent data. I did mess around with FigureXP. Like you stated Mark, in the KE Readings section if the center two zones are closer to flat and the 4th zone is higher that the ideal value then the star tests look like what I was seeing.
Is there a link that really does an excellent job of explaining a test with a Couder Mask? Maybe if I read up some more on it I can produce better results.
Joe: I'm not sure if they do or not. I know they meet over in Pensacola but haven't met up with them yet. I've just recently gotten back into astronomy after a 2 yr hiatus.
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Orion XT8 - Orion StarMax 102 EQ
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mark cowan
Vendor (Obsidian Optics)
Reged: 06/03/05
Posts: 2159
Loc: salem, OR
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David,
Try this by David Harbour - if you like it then buy the book.
Best,
Mark
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DavidinFL
member
Reged: 08/28/09
Posts: 52
Loc: Navarre, FL
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Mark, I had read that link before but reread the testing section after you posted it. I decided to go with an Everest mask at the author's reccomendation.
I used 5 zones like he suggested and got much more consistant data. The 1st and 2nd zones seemed to act as one zone so I gave them the same reading. I did have some trouble on the 5th zone. It was hard to get to line up exactly. That's the zone I'm least certain about.
I plugged the results into FigureXP. I'll post some screen caps below.
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Orion XT8 - Orion StarMax 102 EQ
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DavidinFL
member
Reged: 08/28/09
Posts: 52
Loc: Navarre, FL
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Surface Error
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Orion XT8 - Orion StarMax 102 EQ
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DavidinFL
member
Reged: 08/28/09
Posts: 52
Loc: Navarre, FL
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Star Test
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Orion XT8 - Orion StarMax 102 EQ
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