41 replies to this topic

[Bill Grass]

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!

[Bill Grass]

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!

[Bill Grass]

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!

[Bill Grass]

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!

[Bill Grass]

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!

[Bill Grass]

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!

[Bill Grass]

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.

[Bill Grass]

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!

[Bill Grass]

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!

[Bill Grass]

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!

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?

[Bill Grass]

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!

[jrcrilly]

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

[Bill Grass]

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

[jrcrilly]

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.