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Just received an Odyssey Compact. Need some help..

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#1 Dan F.

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Posted 06 June 2011 - 03:49 PM

Hey all, I haven't been present on here too much since joining last fall, but I have been doing a lot of binocular observing since getting into the hobby a little over a year ago.

I was just given an old Odyssey Compact 10" dob w/ a Telrad, JMI miniMAX and two Orion 2" eyepieces (ER 32mm + PL 50mm). The only problem is that, as much as I know about dobs from using them at club meetings for awhile, I'm a bit overwhelmed. I know the what the Telrad is and how to use it and that the eyepieces should be excellent, but I have no idea what this computer thing is and what it does, whether it works or not, how to collimate a dob or whether or not the mirrors are secure in there. All I know is that the telescope has been sitting in a garage for a few years and worked well before being put away, the primary is slightly dirty, the Telrad works and this other computer at least turns on.

I guess my question is should I jump out and try it...or are there a few basic things I should know or look over first?

I would like to (rather soon) construct at the very minimum a truss tube dob utilizing the optics, PVC focuser, etc. because this thing is HEAVY. But otherwise my immediate concern is how well this works as a visual instrument.

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#2 Don W

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Posted 06 June 2011 - 04:06 PM

Get in touch with JMI and see if you can get a copy of the instructions. It's really quite easy, but you need some guidance for the first few attempts.

#3 bob midiri

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Posted 06 June 2011 - 04:19 PM

Dan I had one and it took about an hour and a half to make it user friendly. First i got real teflon pads and a piece of ebony star wilsonart "formica". I wrapped the side bearings with same width ebony star, I replaced those four (two on each side board) nylon buttons they called sliders with teflon about 1.25inch in length and little wider then the thickness of the side board. On the ground board and bottom board I removed what looked like vinyl flooring material and replaced with ebony star, and four pieces of Teflon pads 1.5x1.5" the fourth pad is placed as a washer between the ground and bottom board with the pivot bolt going right thru the middle. The three pieces of teflon are 120 degrees apart roughly 2/3 distance from center pivot bolt to edge. Then I replaced the focuser and had a tremendous user friendly star party telescope. The motions where now buttery smooth. It wouldn't take much to fix it up without changing its classic looks. Bob

#4 apfever

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Posted 06 June 2011 - 06:13 PM

Dan,

Let's get the unit visual first and foremost by eliminating any gross collimation errors. You need no collimation tools at all for starters, exept your eyeball. For adjustments, you'll need any screwdrivers or allens to move the mirrors.

Look in the focuser without eyepieces. For now, just move your head around to locate your eye in the center of the focuser draw tube. You can find this position by making the draw tube look even and centered down it's length. Move your head way off to the side and note how the end of the draw tube is not centered with the top. Then use this effect to center up your eye.

What you want to see is:
1. the focuser tube even and centered
2. the secondary even and centered in the draw tube
3. the primary image centered in the secondary
4. the reflection of the secondary centered in the primary
5. your eyeball staring back at you centered in the reflection of the secondary.

OK. This is meant to be fast, down and dirty. The light coming into the scope is reflected by the primary into the shape of a cone. The goal here is to have the tip of that light cone going somewhere into the focuser, nothing more. You'd be surprised at how many back room and basement newts don't even have the primary light cone even close to the focuser tube.
Start at the front of the OTA. Measure the center of the secondary mount from the edge of the OTA. A piece of paper, marked to the sides of the OTA, folded in half, works good for locating the center. This is usually pretty close. If it is an 1/8" off I'd move on, over 1/8" I'd take note, and anything close to 1/4" would definately have me disgruntled because......the Coulter sucks for having any centering adjustments. The good thing is this is usually close enough. Ignore anything you've heard about secondary OFFSET since it is very small in an 8" and trivial for this barbaric caveman rough in.
Now center your eye in the drawtube and look at the physical secondary, IGNORE any reflections in it and concetrate on the secondary actual glass. Ideally you should see the whole reflective surface centered in the draw tube and the surface should be round looking, not oval or egg shaped. For now, if you can see the whole surface (even if not centered) it will get you first light. This is usually OK, and a good thing because Coulter sucks again for no adjustment to move the secondary up and down. IF the secondary is centered in the OTA, and the sides of the secondary are NOT in the drawtube then you need to shim the focuser side to side but this is usually not the case.

Next, you be thankfull that the primary is centermarked. Looking into the secondary you want the primary image centered. You loosen the end bolts on the beefy spider bar to rotate the secondary forwards and bacwards, and loosen the back plate on the secondary to rotate it for side to side.

Next is the Primary. You want the IMAGE of the seconday centered in the primay. Use the primary collimation screws for this. It seriously helps to have some one adjusting the primary while you watch the image in the focuser tube.

You may have to readjust the secondary if the primary was grossly out of whack, then readjust the primary again.

That should do it! To get it all ready for a quickie, you usually only have to adjust the secondary to center the primary image, and adjust the primary to center the reflection of the secondary. All just by visual while making the inside of the focuser draw tube look straight and even. All the other stuff is usually good, but check it all for gross outage. It is quite likely you may see everything fairly close with your eye staring back at you right off the bat.

#5 Dan F.

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Posted 06 June 2011 - 08:22 PM

Thanks for the info, apfever! I'll metally process this later, but for the moment I can tell you that the secondary is circular in appearance and is perfectly centered in the 2" eyepiece opening. However, the reflection of the dot in the center of the primary is about halfway between the center and edge of the (reflected) secondary when looking at the secondary through the eyepiece opening. The secondary has no adjustment screws of any kind.

#6 Dan F.

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Posted 06 June 2011 - 08:36 PM

I've attached a photo to illustrate...

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#7 wfj

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Posted 06 June 2011 - 10:16 PM

Congrats on your gift.

I have one - its my default scope that I always leave cooled down in a well dessicated RubberMaid storage container.

Your first concern is the optics of course. I didn't trust the quality of mine for a while - many owners of these claim that with the standard enclosed mirror cell, they never, ever ... cool down. Take this seriously when testing the optics - it fooled me for awhile.

Also, take seriously doing an extremely good job of collimation, along with the requisite star tests. Mine had some astigmatism - again every time I blamed the optics. Turned out in cleaning the mirror, when I removed it from the ... cell ... found that the mirror supports weren't placed well. Careful reassembly completely eliminated the problem.

Mine has a mirror that is well corrected and very sharp - it way out does a very nice SCT to 500-600x when the atmosphere allows. Its weakness is roughness in the polish - my 12.5" Discovery made mirror out performs it (unsurprisingly).

I found that I preferred a much smaller diagonal - doing comparisons between 1.77, 1.83, and the supplied 2.6", found the 1.77 did best when I compared details last Mars opposition. This required a lower profile focuser and pushing the mirror back 1.7" - which vented the mirror better (haven't got around to replacing the mirror cell - too many projects).

You're right about the heft of the scope - my daughter loves to use it, but can't heft it around by herself. A lighter weight rocker and mirror cell can make some improvement, but its the tube where the weight mounts up. And yet, its the whole simplicity of the solid tube scope that gives it such ease of use.

Its big enough to hunt galaxies with, yet easy to use with a lawn chair or stool. I've often thought of thinning down my scope herd by having it move on ... but it keeps getting used too much.

The kids at star parties find it very approachable. I have a old "pac bell" tool tote that I invert and the small ones stand upon to catch a peek. Some have even asked me about the telrad, then how to point it, then where to find things ... one time a 12year old took over after about 20 minutes of this ... and ended up running the scope for the benefit of others the rest of the night. Hard to let go.

#8 Dan F.

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Posted 07 June 2011 - 06:53 AM

Thanks for the input, wfj. Though I'm curious if I should pull the primary out to inspect it. It is a little hard to tell from the photo in my original posting, but the primary is DIRTY. Furthermore I'm wondering where you got a Rubbermaid container large enough to contain such a large scope.

On one hand I want to keep this as it is because it's a classic scope, but on the other hand I, as a broke college student who could afford not so much as an Orion 10" dob, would rather spend $100 to construct a truss tube (or single or dual tube) dob utilizing the optics so I can have a MUCH more portable scope. I LOVE the idea of the PVC focuser because it seems so much finer than the average rack & pinion unit, and since I cannot afford a MoonLite this is a huge plus.

#9 wfj

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Posted 07 June 2011 - 09:09 AM

First check the optics - unless there's so much dust that you can't even tell its a mirror, there's more than enough reflection to collimate and star test. Do this first to understand exactly what you've got - to yourself. Cleaning comes later. Trust me on this.

What I next did was compared star tests with others XT10's.

The Rubbermaid container is the 33.5" x55" 52 pound one - got one on special at Home Depot. You can find them on craigslist also for little (sometimes for free!). Make sure you get some containers of silica gel (crystal) kitty litter (I also seal the tube with a cover I've made that seals the top, then throw in a sock filled with the litter as well), attached to the spider. The scope is used where we get huge amounts of rainfall, so its necessary to do this two level approach. You can only do this with a sealed bottom solid tube scope like the Coulter.

You may have found the perfect scope for you them - you get the best of all of these worlds - if its a good one - you get something thats cheap, compact, is a classic, can give you excellent planetary views, and allow you to troll through the Virgo cluster. Plus it fits in the trunk of most cars.

My observing friends thought very little of it at first, and wanted me to get an Orion XT10 instead - part of the reason I thought poorly of it all the time. So I forced myself into an objective test - literally, comparing scopes many, many times. Once I got used to the scope and its foibles - cell, cooling, too big secondary, ... - my comparisons with the Orion were similar - in a few cases better. The few better ones finally latched me on the "Coulter optics inferiority" syndrome as bogus in this case. It isn't perfect - but slightly rough optics is fairly common in any mass produced scope - comes from rushing the polishing stage to keep on production quota.

I also didn't want to pay for a elaborate focuser for such - I got an inexpensive 2" helical to use for wide angle views. Budget for a coma corrector as your long term next purchase in the far future - ahead of a fancy focuser.

I'll get some pics for you. In short, its likely you won the lottery for what you need and can use - don't let anyone tell you otherwise.

#10 wfj

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Posted 07 June 2011 - 11:24 AM

Rubbermaid 374801OLVSS Large Horizontal Outdoor Storage Shed

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#11 wfj

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Posted 07 June 2011 - 11:32 AM

Contents - note that if rocker were only a few inches shorter, scope could be kept mated with rocker in horizontal position where it could slide/roll out onto deck - less than a minute setup/tear down time. Pac Bell tote supports other side - it also contains silica gel containers, in addition to sock inside tube.

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#12 bigwooly

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Posted 07 June 2011 - 01:39 PM

The computer thing as you so delicately called it is worth more than the whole scope is if they work. It is a push-to system. here's the short wiki about what they are. http://en.wikipedia....setting_circles

if you don't intend to use the digital setting circles(JMI Minimax) encoders, hardware, etc that go with it. you could definitely sell them to put some more money in your pocket for either a truss tube or sonotube rebuild.


#13 wfj

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Posted 07 June 2011 - 05:54 PM

you could definitely sell them to put some more money in your pocket

Could be bad idea for you. Try something else.

Hold on to all of the stuff that came with the scope. If possible, even beg for more from the original source.

Why? Two reasons - someone put a lot of time and effort into building up a "kit" of stuff - they might have had some good ideas too. Also, since you were given this, others might have more knowledge that may help you, including good places to go, other people local that can help. There's a lot that happens with "gifts" sometime.

Second reason is that you don't know what you've got yet, and quite likely you'll never get it this cheap again, nor as well integrated already - possibly debugged and working. Once you do understand what you have and how to work it, then you can decide what you like and what you're less interested in.

"Push-to's" are better than GOTO scopes for beginners too. You get a better feel for the sky. I have one on a Celestron - works great.

Another thing - unless you are talented at selling used astro gear, you probably won't get much for it. And, in my opinion, you can get more selling as a whole kit than as split up. With a few exceptions.

With a really good 10" mirror, I've seen some build custom truss telescopes out of Coulters, and sell them for 2x+ than with the "red tube" scope. The mirror can be worth more than the scope.

In general, you want to find out how to work it, how well it works, and if it suites. Saw someone swap a 10" dob rig for a 8" SCT w/CCD - one was leaving astrophotography for visual while the other did the reverse.

It is possible that you end up buy/sell/trade scope parts for others - nothing wrong with that. But do so knowingly.

You've got a lot to learn, and from a lot of guys here who know a lot, and can help a lot. Let them.

#14 Dan F.

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Posted 07 June 2011 - 09:26 PM

Thanks for the info, wjf! Where I stand now is that I've been fooling with the collimation stuff and have yet to figure it out. HOWEVER...I just finished looking at the moon haphazardly and found that the thing is ridiculously sharp! The only comment I have on this is that the outside edge of the moon appeared to have two or three repeated images of the moon even though the moon itself had no ghosting on it. Hopefully this is just due to the lack of collimation.

So the digital setting circles are what the Orion push-to dobs have. That's cool. A guy in our club has his out every observing session, though it seems he can never get his calibrated. I found out mine works fine (don't know about the precision though) but will likely not use them at first because I'm more interested in learning the easier objects manually.

#15 wfj

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Posted 07 June 2011 - 11:43 PM

Dan,

The multiple images might also be if you are looking through something like leaves in a tree canopy, and you are slightly out of focus. Adjusting the focus may cause the images to combine - there is a thing called a bahtinov mask (multiple holes in a tube end cover) used in photography to achieve a sharp focus - you might be doing this by accident.

A properly collimated 10" has amazing detail - with mine I really was surprised to see the hollow in Jupiter's GRS, and occasionally (when seeing allows) can see fine white spots and dark barges floating near Jupiters equator too. Can see craters in the floor of craters down almost to a mile.

Right now you should gain experience with your scope, and learn how to use it better and better. Spend time looking at Polaris - its a double, but better yet it doesn't move much so you can spend time focusing in/out, you should see a bullseye that grows into a dark spot at the center - the degree you are off of collimation you'll see the spot off center - you need a short focal length eyepiece for this (10mm or less).

Where the push-to comes in handy at your level is in two ways - 1, they allow you to see a lot of objects successively and 2. they can be used in reverse to identify what you are looking at when you come across something.

Its important (and fun) to find everything by hand, But sometimes keeping track of like a bunch of galaxies all nearby (like the Virgo Cluster), you can see where you are so you can back track to a sky chart to find the names/descriptions of neighbors.

#16 Rich (RLTYS)

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Posted 08 June 2011 - 05:16 AM

Rubbermaid 374801OLVSS Large Horizontal Outdoor Storage Shed


That is so cool!!! I've never seen anything like that before.

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#17 Dan F.

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Posted 09 June 2011 - 10:49 AM

The two issues I'm having right now is collimating - I can't seem to adjust the primary properly no matter how I try (and I know how to adjust a primary on a traditional dob) - and the bulk / weight of the thing because I have to haul it down a couple flights of stairs each time I want to use it. It does fit in my car's trunk, though barely, so the size isn't really an issue in regards to transportability. It is because of the bulk and weight that I was interested in constructing at least a crude implementation of a truss tube dob. Storage plays a factor right now as well, but again, the biggest issue is weight / bulk in getting it out to my car.

Question regarding collimation. I know how to collimate a 10" LX200 and as such am familiar with the fuzzy "doughnuts" you get when going severely out of focus. My question is can I use a cheap Meade eyepiece for this? By cheap I mean from a $200 department store telescope.

Would it be possible to solve my collimation issues by using a traditional mirror cell? I tried to get the tube off the base yesterday to take a photo of the mirror, but the three threaded rods that run the length of the tube prevented me from actually separating the tube from the base.

Note that I'm not discouraged by any means...this is / will be better than having to drive 45 minutes to use an observatory for visual.

#18 bob midiri

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Posted 09 June 2011 - 11:42 AM

center spot the primary with one of those paper reinforcement rings, buy yourself a cheshire eyepiece (orion sells them), and you will have no problems getting it collimated. An F4.5 needs to be very well collimated. Bob

#19 Dan F.

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Posted 09 June 2011 - 04:41 PM

I think I've figured out what's going on here. The base / mirror cell, which appears to have been modified by the previous owner, has some play where one of the threaded rods passes through the wood. Furthermore once I got the tube off I found that the mirror itself wasn't taped to anything as I had previously been told, but rather simply resting on felt pads. Finally, one of the squares that held the mirror up against the backing plate was loose, which is probably why there was a slight clinking sound every time the scope was moved or taken from horizontal to vertical.

Now the questions are should I clean the mirror or leave it as is, and should I redo the base / mirror cell or continue to try to use the scope as is?

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#20 Dan F.

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Posted 09 June 2011 - 06:49 PM

And here's the clean primary, carefully cleaned per the instructions provided by Optic Wave Laboratories. There are still plenty of spots on the mirror, but these won't go away. Point is it's clean compared to what it originally looked like.

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#21 shawnhar

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Posted 10 June 2011 - 07:29 AM

Nice cleaning job! That mirror came out much cleaner than mine ever will!
I was very surprised to see a 9 point floating cell and collimation rods up the tube, certainly not stock. I think you will have much fun with this scope and with your skills you will have no problem getting where you want to go.
Those little "squares" are the retaining clips, they are only there to keep the mirror from falling out and should never be tight. If you do tighten them you will see stars that look all funny shaped, shockingly little pressure can deform the mirror's shape and affect the view.

Oh yeah and collimation, cheapest effective tool is a Newtonian collimation tool, or combination tool, it has a sight tube, crosshairs and cheshire all in one, this allows you to place and tilt the secondary and tilt the primary with one tool. I have the Orion one, all metal, very good.

#22 apfever

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Posted 10 June 2011 - 08:59 AM

I believe the original cell had the primary just siliconed to it. My coulters were all glued mirrors, even the 17.5 inch. Somebody has cut the cell, added the 6 retainer post, added the 9 point triangles, and added the collimation rods that go to the top. There must be some sort of holder to keep those rods from flopping around in the tube.

You need to examine the cell to see how it has been modified and check for the rods tilting the cell correctly.
In other words, make sure the collimation action is legit.

#23 Dan F.

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Posted 10 June 2011 - 10:11 AM

Yeah, that's the problem...there's actually some play in the action. But I'm wanting to build a new cell anyway, so it's not a big deal.

So the clips shouldn't be tight, but can they be touching the mirror so as to keep it from flopping around like it had been? I'm thinking I'll have the collimation action between the new base and the structure that holds the flotation points, and the clips will come off that structure so the mirror won't move relative to the clips when being collimated. Thoughts?

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#24 wfj

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Posted 10 June 2011 - 12:08 PM

You need to support the edge at the C.G. of the disk edge in at least two points.

The sole advantage of the Coulter cell - besides being cheap - is to have no clips obstructing.

One can have tabs extending from the T frame with a bearing point approx 0.7" up the edge of the mirror, then secure the mirror with the tape (or other means). The tape doesn't bother me - it functions like the clips if done in moderation.

The original "red tube" cell is three pieces of particle/OSB board - the outer cap that is visible, adhered to another that form-fits the inside of the tube, and a third that supports the mirror, which is attached to the two other boards via 6 screws in a push/pull configuration. Mirror rides on three foam pads (in mine incorrectly located), with the edge attached with a single continuous strip of duct tape running twice around the circumference, and finally secured by a "pipe clamp" that joins the mirror/board edge in a balanced manner.

The Orion DSE cell was three enormous blobs of silicone glue (approx 2" diameter and 1/2" thick) with duct tape surrounding - no pipe clamp. Three one inch holes for ventallation, otherwise very similar (not a push/pull but very stiff springs and wing nuts.

#25 Dan F.

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Posted 10 June 2011 - 05:24 PM

So what you're saying is that a mirror riding on the six or nine points but also duct taped around the lower piece (same dia. as mirror) can be just as effective as clips? In the above example would that simply mean having a half inch wood ring between the "T" and flotation rocker mounting points?

I stopped in the hardware store today to see what kind of square tubing they had. Turns out I could get four feet of some aluminum or steel stuff of roughly one to one and a half inch for ten bucks. Is there anything specific I need to pay attention to here, or will this be sufficient? Which material should I choose?

I've seen some cells that mount in a tube with just three metal angles as attachment points rather than utilizing a full wooden ring. Should I lean towards one method over the other?

I'm seriously debating redoing the spider / secondary mount as well, both for collimation purposes and so I can learn what's involved. I did some research like I did for the mirror cell but found next to nothing. Can anyone point me in the right direction, e.g. forum threads, websites, etc. Thanks!






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