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More on my new AR-5

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#1 Bill Grass

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Posted 07 December 2003 - 10:37 PM

I just took the AR-5 outside for another run. I don't know what I did to it between the first time I looked through it and tonight, but somewhere along the line my tinkering seems to have improved the optical quality!

Yesterday I played around with the focuser hoping to improve the collimation. This was unsuccessful (but this method worked with my ED80). I played with the lens cell, but that didn't help. I thought maybe I could play with the placement of the focuser & lens cell since there's no real collimation method on this scope. Finally I gave up.

Earlier today I unscrewed the ring that holds the lens in its cell. I shook the tube a bit to make sure the lens was settled flat. Then I tightened the ring again. I just checked collimation with my collimation eyepiece, but it's still off.

However, I got some really nice, sharp views of Mars & Saturn a little while ago! I cranked the power to nearly 300x on Mars, and it was still fairly sharp. The chromatic aberration I saw a couple of nights ago wasn't nearly as bad tonight; in fact, slapping on my V-block filter pretty much eliminated the purple. I don't know what's going on, but I may have to reconsider getting rid of this scope. And that brings me to a few quesions for you AR-5 owners!

First of all, could any of my tinkering have improved the optics?

Is there anything else I can do to adjust the collimation? When I focused the scope on a bright star, the diffraction rings weren't centered around the Airy disk. The stars were still sharp, though.

Also, I'm using my SkyView Pro mount with this AR-5 (since it's the only mount I have). What kinds of mounts are you using with this scope (LXD55s & CG-5s?)? And how high from the ground is the eyepiece when the scope is pointed at the zenith? I'm just curious because the tube seems to be almost more than my mount can handle. Focusing is very tedious since the image jumps around so much. I don't think it's the focuser itself, since I tightened it up a bit. However, everything was not balanced since the single counterweight can't balance the weight of the tube. I ordered another counterweight from Orion. Will that extra weight (and therefore good balance) help reduce all the jiggling that goes on when trying to focus?

I'd really like to keep this telescope, but I want it to perform at its best. Thanks for any information! :)

#2 Guest_**DONOTDELETE**_*

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Posted 07 December 2003 - 11:14 PM

It's possible that your objective could have been pinched and relieving some of the stress on the objective may have helped. If your diffraction rings are off as you say, you could (cautiously) remove the lens cell and place a shim under the rim where you think it needs to be to correct the error.

There is a similar thread on correcting the collimation on an 80ED refractor if I'm not mistaken using this, or a similar method.


#3 Guest_**DONOTDELETE**_*

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Posted 07 December 2003 - 11:17 PM

Have you tried loosening the screws and pushing the lens cell in the right direction? Though I'm not familiar with that scope, there should be some play between the mounting screws and the cell mounting holes. If there is enough slack you should be able to get it very close to perfect. This worked on a 60mm refractor I used to have.

#4 Guest_**DONOTDELETE**_*

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Posted 07 December 2003 - 11:57 PM

The AR-5 lens cell is uncollimatable. At least by conventional methods.

#5 Guest_**DONOTDELETE**_*

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Posted 08 December 2003 - 12:17 AM

Your right about not being able to adjust the lens cell, I removed mine tonite and it slids onto the OTA very snug then 3 screws attach it. No way to adjust this setup. My best fix on mine was to realign the focuser it was really off bad. made a world of difference. Nice pinpoint stars and very little false color now. If you loosened up the objective maybe it was pinched. Not a bad scope when its all tweaked, just a tad on the large side is all.
Dave

#6 Bill Grass

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Posted 08 December 2003 - 01:21 AM

Yeah, I tried loosening the lens cell & moving it around a little. But like Dave said, it fits on there pretty snugly. There's really no leeway to change its position even the slightest bit.

Dave, how did you realign the focuser? I removed the 3 screws attaching it to the tube and moved the whole assembly around while looking through my collimation eyepiece. But it appears that I would have to position the focuser at a ridiculous angle in order to get the collimation dead-on. In other words, the little bit that I would be able to move the focuser & screw it back into place isn't nearly enough to correct the problem.

I'm determined to get this thing to work for me! :mad:

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Posted 08 December 2003 - 08:43 AM

Bill,
What happened to me first was that I used the scope on a decent evening and saw coma shaped stars at the outside egde of view, and there was just terrible CA. I started thinking I had bought a real Rat. I decided to try to see if adjusting anything would help, so I brought it inside and re-adjusted the focuser tensioner so it didnt wobble much, and cleaned and re-greased with light brake grease on the rack & pinion gears. Next, I moved the focuser to its middle position where most viewing would be at and then shined my flashlight down the main lens to eyeball the focuser tube to the baffles. Since the lens cant be moved obviously the focuser has to be the adjusting point. It was WAY off center! I loosened all 3 screws and tilted the focuser body until the focuser tube was perfectly centered. I then added a large washer under ea. screw and tightened them. The washers hold the assembly firmly otherwise the screws would want to recenter to the old position again, and I also added a small strip of striping tape around the OTA where the focuser body attaches as an indicater of accidental movement just in case. I then proceded to test it again and wow what a diff! No more coma shaped stars and almost no color I think I have a really good figured lens, better than average im guessing for a 9.3 fl.achro. Anyway, I cant see how I could tweak it any better without having an adjustable mainlens where one could adjust very slightly with a screw turn so I stopped messing with it. Of course if Meade ever offers a collimatable mainles for the achro 5" Ill jump on it. The 5" ED is setup that way but it dosent match the the 5" achro im told. Anyway, all refractors without collimatable lenses should be checked this way, the focuser is always the weak link in collimation and must be done first anyway before the lens is ever touched ever. Ive only owned 1 refractor that didnt need focuser tweaking and it was of course an APO. Do as I did and look down the lens and see if the focuser tube is centered perfectly with the internal baffles, the eye dosent lie, and dont be concerned if the focuser now looks cocked on the OTA all that matters is that its improved its quality of views in the end. My focuser base looks angled but when the focuser is pulled out it looks straight with the OTA which is what it needed. I didnt notice any diff rotating the focuser body, alignment was all that was needed. Dave

#8 Bill Grass

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Posted 08 December 2003 - 09:46 AM

Thanks, Dave! Did you use a collimation eyepiece/laser or just your eye? Maybe I'm worrying too much about what my collimation eyepiece shows. I did look down the tube once and the focuser seems fairly centered, but I'll look again when I get home from work & make sure it's dead center.

Last night I tried playing around with the lens cell & sticking shims underneath certain points, but that didn't really solve anything.

Thanks again for the advice! :bow:

#9 Guest_**DONOTDELETE**_*

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Posted 08 December 2003 - 11:58 AM

I dont use a special eyepiece on the Meade I dont think it would be worth it since the mainlens cant be tweaked anyway. Final adjustments of a minor amount would have to be done at the lens end anyway. Plus the focuser has some non removable play so the collimation eyepiece would always read off everytime the focuser was touched. Just making sure the focuser is dead on is 99% of the fix I assure you unless you have a bad mainlens to start with. I doubt lens pinching is a prob anyway since the whole lens holder including the lens stop is all plastic not a pc. of metal to be had anywhere except the knife edge lens base that the lens sits on. Sounds like yours is close already.

#10 Bill Grass

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Posted 08 December 2003 - 12:03 PM

Thanks, Dave!

Another question: do you use yours mounted on the LXD55 mount or do you use something else? I was just wondering if my SkyView Pro mount is a little lower than the LXD55 or CG-5 since the eyepiece is almost on the ground when the tube is pointed at the zenith! I know any mount will put the eyepiece close to the ground in that position, but I was hoping I could at least get it high enough for me to sit on a low stool or chair to view. That's much more comfortable & practical than sitting cross-legged on the ground! :p

#11 Guest_**DONOTDELETE**_*

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Posted 08 December 2003 - 12:14 PM

Im using the LXD55 W/autostar. And I broke down and bought a Starlight multi position viewing chair, a must have for refractors im afraid, at least for me. I only want to haul out 1 chair for all positions period, it was expensive but was worth every penny. Probably the only pc. of equipment Ill never trade or sell off in the future thats for sure.
I usually have my EQ legs set to 1/2 their length, that way I still have reasonable stability. If just viewing the moon or planets and they arent in the Zenith I keep the legs un extended then its really solid. Im only 5' 6" tho so a tall tripod isnt really necessary for me anyway um, im short in height and tall in stature! :lol:

#12 Bill Grass

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Posted 08 December 2003 - 12:20 PM

I've been thinking about getting one of those chairs myself. I just don't want to spend the money!

Maybe I'll see about getting some longer tripod legs for my mount. (Of course, this is if I decide to keep the AR-5!!)

Thanks for the info! :D

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Posted 08 December 2003 - 12:26 PM

Bill,
I dont know if your into a lil woodworking but there are some nice plans on the web for making viewing chairs. I printed a set for a friend and he said it didnt look hard to make and it cost about $40 in parts. Myself, I have no interest in any woodworking anymore as Ive done it for over 25 yrs just got old I guess. I went the lazy rout, I can get away with it at my age 45, hehehe....Dave

#14 Bill Grass

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Posted 08 December 2003 - 02:37 PM

I just built a facade & mantle for my fireplace, but I don't think it'll appear on Antiques Roadshow anytime soon! I could probably get by & build something that may hold together. I've never been into woodworking or anything like that. Usually I go the lazy route, too...and I'm only 28! :lol:

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Posted 08 December 2003 - 03:08 PM

I hear ya, bragging rites dont mean much to me anymore. I do things this way: If its easier, less hassle, and less work on my part, then Ill just do my job and just buy the item saving a lot of effort, time, work and headbanging or guessing. It always works out better that way. I learned a good lesson doing trade work for a doctor once, he wanted 10 hrs to my one from him, I dont think so anymore.......Im a wise old Owl now to that game. Dave

#16 Bill Grass

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Posted 08 December 2003 - 03:14 PM

If its easier, less hassle, and less work on my part, then Ill just do my job and just buy the item saving a lot of effort, time, work and headbanging or guessing. It always works out better that way.


I certainly agree with that!! That's the way I usually feel about most things.

#17 Bill Grass

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Posted 08 December 2003 - 07:09 PM

Well, I just double-checked my focuser alignment by peering down the objective end. It looks dead-on to me. So I'm gonna stop worrying about it & just enjoy the views I get from this thing! :cool:

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Posted 08 December 2003 - 07:34 PM

HAve you decided the views are enjoyable after your tinkering? I sure hope so because I still have my eyes set on this scope!

Compared with the 80ED, is it worth having both scopes?

#19 Bill Grass

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Posted 08 December 2003 - 08:27 PM

I think so, Tom. After most of my tinkering, I took the scope out & got some really, really nice views of Mars, Saturn, & the Moon. I checked out the Double Cluster, but it was pretty washed out. However, it looked about the same as my ED80 shows on a moonless night! The bright stars I looked at didn't seem to have nice concentric diffraction rings around them, which led me to believe that the collimation is still off a little. Then again, the stars were twinkling a lot, so I'm gonna wait for a nice steady night & see what they look like.

I think it'll be worth it to have both scopes! When the moon disappears again, I'll test the scope on some clusters & other DSOs.

I just need to figure out my mounting issues! :question:

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Posted 08 December 2003 - 08:41 PM

I thought the SkyView Pro was on par with the CG5 and LXD55. On the LXD55, this scope looks right at home and should be well within its means of handling it. I know it is disheartening to have a scope that doesn't perform as it should and I do understand waiting for good viewing. I'm still waiting for really good viewing with my 80/9D... :crazy: (I like what I've seen so far!)

Hang in there. See what Scott has to say about it also...he said you guys might actually be able to get together real soon! I hope you can grab Carolyn if you do, it would probably be a good benchmark with her 8" Dob and she can see what all the hub-bub is about the SV nighthawk and 80ED.

#21 Bill Grass

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Posted 08 December 2003 - 09:20 PM

Well, the SkyView Pro, according to everything I've read, is pretty much the same as the LXD55 & CG5. But I think one difference, and somebody correct me if I'm wrong, is that apparantly the SkyView Pro's legs don't extend as far as the other mounts' legs. This puts the eyepiece so close to the ground I have to actually sit on the ground to view stuff at the zenith! Like I mentioned above, I'd like to be able to at least sit in a chair or something! (Anybody have some long, solid, SVP-compatible tripod legs hanging around??) Other than that, I think (hope) the mount will be fine after I add the extra 11 lb counterweight I ordered.

I wish I could go give the 5" another run tonight, but it's overcast! :mad: :mad:

Yeah, Scott & I are talking about getting together with our scopes sometime. We'll certainly let you know what happens! Carolyn, if you're reading this, would you be interested?

#22 Bill Grass

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Posted 08 December 2003 - 09:27 PM

By the way, last night I thought I had blown up my declination motor! When I tried tightening the clutch, it would tighten to a point & then keep on turning. The image in the eyepiece wouldn't move when slewing, either. I pressed the button & looked at the motor's gear, and it was turning just fine. Then I figured out the problem...the big AR-5 must've bumped the motor assembly & separated it from the gear that actually turns the declination axis! I was so relieved that it was fine! :o I moved it back & re-tightened the allen screw holding the motor.

Maybe I should re-post this in that other thread about the stupid things astronomers do! :lol:

#23 jrcrilly

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Posted 08 December 2003 - 09:30 PM

But I think one difference, and somebody correct me if I'm wrong, is that apparantly the SkyView Pro's legs don't extend as far as the other mounts' legs. This puts the eyepiece so close to the ground I have to actually sit on the ground to view stuff at the zenith!


It's an issue with medium long refractors. Vixen makes a pier adaptor to go between the tripod head and the mount that gains some altitude. I'm pretty sure James Grigar (Astrosky) makes one also.
http://astrosky.home...m/Astrosky.html

#24 Bill Grass

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Posted 08 December 2003 - 09:35 PM

Thanks for the link, John. James is only about 100 miles away from me!

#25 jrcrilly

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Posted 08 December 2003 - 09:44 PM

Thanks for the link, John. James is only about 100 miles away from me!


Cool - he's one of the good guys. He makes a complete pier to replace the tripod also, which really helps the LXD55's. The SVP looks as though the tripod is pretty solid so just the extension should do the trick.


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