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Posts Made By: John MacDonough

January 2, 2009 05:35 PM Forum: Equipment Talk

Removing IntelliScope encoders

Posted By John MacDonough

Hi all,

I have an Orion SVP mount with IntelliScope encoders. Does anyone know how to safely remove the encoders so the mount can be cleaned and regreased?

November 29, 2009 01:26 PM Forum: Equipment Talk

Orion SkyView Pro go-to trouble

Posted By John MacDonough

Hi all,

I'm hoping someone has had this experience and fixed the trouble. I recently added the go-to kit to my SkyView Pro mount. I can get fairly good pointing accuracy using the 2-star alignment, but when I attempt a 3-star alignment it almost always fails, even after as many as four attempts. I've e-mailed Orion tech support and done everything they suggested except updating the controller's firmware. Any other ideas? Did updating the firmware help?

May 1, 2011 08:02 AM Forum: Telescope Making

Help needed with Cassegrain assembly

Posted By John MacDonough

Good morning all,

I've about "trial and errored" myself to death, so I'm asking for some help. I purchased a classical Cassegrain mirror set hoping to assemble a telescope. What I'm told by the person who sold the mirrors to me is this:
Primary: 200 mm diameter, f/4
Secondary: M = 5
EFL: 4000 mm, f/20

My problem, assuming the above is correct, is mirror spacing. I was told to target between 628- 630 mm for a back focus of either 275 mm or 210 mm. That hasn't worked out. For one thing, with the mirror cell, focuser and diagonal I have, I need approximately 339 mm of back focus. I've also consulted the VanVenrooij book and calculated a mirror separation of 614 mm for the back focus distance I want. I've currently got the scope assembled with 611 mm separation and have experimented with separations all the way up to 635 mm without being able to achieve focus.

Can someone help me out?

May 1, 2011 08:04 AM Forum: Reflectors

Help needed with Cassegrain assembly

Posted By John MacDonough

Good morning all,

I've about "trial and errored" myself to death, so I'm asking for some help. I purchased a classical Cassegrain mirror set hoping to assemble a telescope. What I'm told by the person who sold the mirrors to me is this:
Primary: 200 mm diameter, f/4
Secondary: M = 5
EFL: 4000 mm, f/20

My problem, assuming the above is correct, is mirror spacing. I was told to target between 628- 630 mm for a back focus of either 275 mm or 210 mm. That hasn't worked out. For one thing, with the mirror cell, focuser and diagonal I have, I need approximately 339 mm of back focus. I've also consulted the VanVenrooij book and calculated a mirror separation of 614 mm for the back focus distance I want. I've currently got the scope assembled with 611 mm separation and have experimented with separations all the way up to 635 mm without being able to achieve focus.

Can someone help me out?

October 20, 2012 07:40 AM Forum: Telescope Making

Tubing sources

Posted By John MacDonough

I'm looking for a company that can provide lengths of tubing the same size as a C8 tube. Any suggestions?

February 13, 2013 07:28 AM Forum: Reflectors

Any experience with Parks telescopes?

Posted By John MacDonough

I don't see much chat about Parks Optical. Does anyone out there have any experience with these scopes? Good? Bad?

February 23, 2013 03:25 PM Forum: Mounts

Orion Sirius: adjusting the worm mesh

Posted By John MacDonough

Do any of you Orion Sirius owners out there know how to adjust the mesh of the worm gear? I've taken the easy cover plates off and didn't find where that can be adjusted. Before jumping off into "lands uncharted" I am hoping to find someone who's explored there before so I can benefit from his/ her experience.

Found it: www.astro-baby.com

February 27, 2013 11:54 AM Forum: Deep Sky Observing

Challenge objects for spring/ summer skies

Posted By John MacDonough

I'm planning a trip to unusually, for me, dark skies. So I'm asking for help in constructing a list of objects I won't be able to see after I return home. I'm not interested in searching out stellar-size planetary nebulae (although I will hunt for 3C-273 because that point of light has a good story). I'm hoping for compact objects as faint as m13 that might show some detail or more extended/ low surface brightness objects as faint as m11 or m12.

An example: a couple of years ago (the last time I went to really dark skies) I was blown away by NGC833/ 835/ 838/ 839. I stared. I sketched. I returned the next night for another look.

What objects have stayed in your memory long after you returned to your local light dome?

May 20, 2013 01:23 PM Forum: Equipment Talk

Orion 2" manual filter wheel threads

Posted By John MacDonough

I'm hoping someone out there can help me. Does anyone know what the thread specification (diameter and pitch) of the 2" nose piece of an Orion 2" manual filter wheel is? The 2" nose piece can be unscrewed from the main body of the filter wheel. I've heard that the threads are M41, but would like that confirmed, and I also need to know the pitch.

August 19, 2013 10:17 AM Forum: Solar System Observing

Saturn Aug 18

Posted By John MacDonough

Last night was one of those nights and I'd be interested to know if anyone else had an exceptional observation. I'm sure it's the same feeling a golfer gets when he hits a hole-in-one that keeps him coming back to the course in spite of all the bogeys in between. I set up my home-made 200mm classical Cassegrain intending to take a quick look at Saturn to verify that the collimation tweaking I had done on Saturday night was an improvement. Holy cow! It was still twilight, really, about 8:30pm. I was immediately greeted by Titan and Rhea. Honestly, Rhea was in-and-out with averted vision, but it was there. I immediately switched from 100x to 200x. Unlike previous views with the 200mm Cassegrain, the Cassini division was immediately visible all the way around the rings. I realize that the Cassini division isn't hard to see, especially when the rings are tilting as much as they are this year. But, as I said, I wasn't able to see them before with this scope. I could also see the shadow of the planet on the rings. I could also see one of the equatorial/ temperate bands on the planet's disc.

I had intended to go out, look for thirty minutes, then go back in. I ended up staying out for over an hour. It was hypnotic. The longer I stared, the more I saw, just like it's supposed to be. I could see, in addition to the equatorial/ temperate band, many striations of tan all across the face of Saturn. I also saw three colors in the rings. Previous to last night I've only ever seen light and dark (OK, yellow and black). Last night, though, I could see the black of Cassini, the yellow of the main body of the rings, and bright white near the Cassini division where the rings get thin. Perhaps I was willing myself to see something that I know is there, but I also bet I saw the Enke Minimum at least a couple of times.

Makes me glad I didn't sell this scope for parts and buy a Mewlon 210. It's pretty cool having something you built working that well.