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Posts Made By: Eric Planalp

May 14, 2005 02:47 PM Forum: Equipment Talk

Laser Collimator Question

Posted By Eric Planalp

Hi All,

I bought one of those run-of-the-mill laser collimators that everybody sells; the one with the 45-degree angle face visible through the side of the unit.

I use a Discovery 10" f/5.6 dob with the standard focuser and a focuser upgrade is not an option at this time.

Even with the laser unit firmly set-screwed into the drawtube, and as much slop taken out of the focuser mechanism as possible, everything just still seems too sloppy to achieve a good collimation. A slight touch on the laser unit will send the beam dancing 1/2" back and forth across my primary.

If I don't find some way to take the play out of the stock Discovery focuser and where the unit slides into the focuser, am I wasting my time with it?

It seems like most of the play comes from where the unit slides into the focuser, even with the setscrew tight. With just one setscrew, it just pivots around it. If I had two setscrews, how would I know the unit was perfectly centered in the focuser.

I toyed with the idea of wrapping a very thin piece of foil tape or something evenly around the part of the unit where it slides into the focuser to "shim" it.

Anybody have any thought or ideas about whether #1. I'm being too picky. #2. There's a way to solve the "slop" problem without buying a better collimator or focuser, or #3, if I should just sell the laser collimator and go back to eyeballing or using a Cheshire system.


Eric Planalp

(I would note that the first and only time I used the unit and then observed,I just did a quick "get the beam back in the hole" by adjusting only the primary and the views were nice and on a good night the star test was about as good as one gets.)

May 15, 2005 06:02 AM Forum: Equipment Talk

V-Blocks and Secondary Spots

Posted By Eric Planalp

I appreciate all the help given regarding laser collimators. I have a couple more questions that I'd rather start over on again.

On the subject of V-blocks and laser collimators. I understand a V-block is a simple machining jig? You lay the collimator in the V and rotate it and see if the beam moves in a circular pattern on a target instead of remaining a dot as it would if the laser is perfectly aligned with the structure of the device?

My collimator is adjustable via three setscrews around the circumference.

If so, what is a source for v-blocks, and how do you use them? My collimator has a tube only about 1" long where it slides into the focuser, then a large knurled ring, then a tube about 3" long with a setscrew you screw in to turn on the laser. How can this device be laid in a v-shaped jig and rotated with the knurled ring in the center of it? I could see if it was a cylinder with the same circumference along its entire length, but what about the larger knurled knob in the middle of everything? What kind of "target" do you use and how far away should it be?

Is there a good website that will explain this to me? I've looked with not much success so far. I hope somebody is saying, "Hell, yes, just go here and read so I don't have to try to explain to this moron."

Also, is it that critical to center-spot a secondary mirror for collimation? It's easy to make a paper template and center-spot a primary, but what about for an elliptical secondary? Never done that. Is there some technique for doing so no matter what the size of the mirror?

And, if I you have a sonotube dob instead of an open tube, how can you even see if the laser is hitting both dots or circle on both mirrors at the same time by looking in the end of the tube? You can't look down the focuser tube and see it because the laser device is there. Do people really spot their secondary?


November 9, 2005 05:27 PM Forum: Beginning Astronomy?

Adjusting a 4-Screw Secondary

Posted By Eric Planalp

Hi All,

What a difference an extra adjustment screws makes! Does anybody have any tips or tricks for making fine adjustments to a secondary holder that has four adjustment screws instead of three? Is it better to loosen them all a couple of threads then work with them all at once? Two at a time depending on where you want it to move?

To me, it seems exponentially harder to make fine adjustments using 4 screws instead of just three.

Any thoughts would be appreciated, unless you think I'm a moron; I'm already on the threshold of realizing that. wink

December 10, 2005 06:29 AM Forum: Beginning Astronomy?

Why Don't You Ever See Any Used Parks Telescopes F

Posted By Eric Planalp

Just curious. They've been around a long time, have surely sold a lot of telescopes and they seem to have a good reputation. Why do you hardly ever see a used one for sale anywhere?
Any ideas?

May 1, 2006 02:01 PM Forum: Beginning Astronomy?

Lunar Scope, Which Of These Is Best?

Posted By Eric Planalp

What do you think would be a better instrument for observing the moon? I'm curious to get some opinions.

Altough I know they're all factors in a way, disregard overall physical size, ease of setup, cooldown, collimation, diagonal quality, atmosphere, seeing, etc.

Utilizing the same UO Orthoscopic eyepieces for viewing, would you choose a 10" f5.6 run-of-the-mill Dobsonian (a standard model Discovery) or one of the new, cheaper 80mm ED refractors like the Celestron or Orion 80mm ED's on an alt-az mount?

Between these two scopes, what optics would provide the best resolution/contrast on the lunar surface? What's your opinion?

February 24, 2008 06:28 AM Forum: Eyepieces

TeleVue Eyepiece Collection

Posted By Eric Planalp

Hi All,

This is just a hypothetical question, but if you were told you could choose and would be given 4 TeleVue eyepieces of any design and size and one TeleVue barlow that would be the only eyepieces you would have to use for the rest of your observing career regardless of telescope size or type and for lunar, planetary, double star and bright DSO observing, what 4 would you choose? I know there are over 150 eyepiece ads on Astromart because we all buy/sell/trade eyepieces to suit our particular scope and type of objects we wish to observe, but if you had to pick 4 TeleVues to use exclusively from now on no matter what scope you had, what would you choose if you didn't have to pay for them?


December 22, 2008 11:27 PM Forum: Equipment Talk

Dew Shield Length

Posted By Eric Planalp

Hi All,

I found some material to make some dew shields for my 100mm (3.93") binoculars. The ID of this material is 4.5". Would an 8" length be okay without interfering with the light path? From what I've read, I think it will be just fine.

Any info or advice would be appreciated.



January 3, 2009 05:41 AM Forum: Eyepieces

TeleVue Plossl Eye Relief

Posted By Eric Planalp

I am considering a couple of old "smooth side" TeleVue Plossls: 26mm and 32mm. Eye relief is a concern for me as I observe with glasses. The gentleman who has them states that the 26mm has 23mm of eye relief and the 32mm has 29mm of eye relief. I've tried to confirm this, but can't find any specs. Does anybody know if these numbers would be right? They're useless to me unless they have at least 20mm of eye relief. Any info would be appreciated. Thanks, Eric

May 2, 2009 02:07 PM Forum: Celestron

Celestron SkyScout And 64-Bit Operating System

Posted By Eric Planalp

FYI, if you use a 64-bit computer operating system, you won't be able to download any software updates for the Celestron SkyScout and will just have to use it with whatever version it came with. They apparently don't have any immediate plans to make it 64-bit compatible, either.

February 22, 2011 03:05 PM Forum: Meade

ETX-125: To Repair Or Not To Repair?

Posted By Eric Planalp

Hi All,

I just bought a new ETX-125AT about a month ago. When it arrived, while handling the scope to mount it on the tripod for the first time, I heard a rattling in the base. If I held the scope upright and tipped it around in a circle, I could hear whatever it was sliding around in the base. I thought it was in the bottom of the base, so after getting some guidance online and hoping it wouldn't void my warranty, I removed the bottom cover. Unfortunately, whatever this object is is in the upper part of the base. I could still hear it rattling around up there but don't really see any way to get into that part of the base and really don't want to. The three spacer washers for the bottom cover were where they were supposed to be. I was hoping it was just one of them, but it wasn't.

When the scope arrived, there was no eyepiece setscrew in the eyepiece holder and Meade sent me one. At first I thought it might be that setscrew, but find it impossible to believe it came loose during shipment and somehow got into the base of the scope.

I called Meade and they said as long as the scope was operating fine (which it is), to not worry about it. At first I could live with that, but now am figuring the thing will probably work fine until a day after my warranty runs out and then it will jam something up, not to mention the fact that if I ever want to sell the scope, any buyer (deservedly so) would be concerned about what kind of object is rattling around in the base.

What would you do? Would you push Meade to take the scope back and find out what's in there and get it out even though they really don't seem to want to do that?