Last updated: 31 May 2007
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Last updated: 31 May 2007 |
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This page is for user comments and information of a general nature or items applicable to all LXD55 and LXD75 models. If you have any comments, suggestions, questions or answers to questions posed here, e-mail them to me and I'll post them. Please use an appropriate Subject Line on your message. Thanks.
Subject: meade lxd 75 Sent: Tuesday, May 29, 2007 05:51:29 From: marco luchetta (swetsuit@hotmail.it) Congratulation for your web site tips, and tricks , and for your FAB picture gallery. I have a LXD75 with a 150 Newton OT,and i was wondering if u ever had troubles with the polar scope collimation, i always find'it hard to get the right accurancy, i hope it's a "problem" that it can be solved easly and once for good, i mean that i don't have to spend hours to get it on the road..... I hope u can help me thanks a lot and clear sky to you. Se ya Marco ITALYMike here: Actually, other than when I first got my LXD55, I haven't had a need to use the polar scope. When I first set up the LXD75 at an observing site I do a One Star Alignment (to align on the North Celestial Pole using the AutoStar and Polaris); then I do a Two Star Alignment.
Subject: lxd75 spur gears Sent: Friday, May 25, 2007 17:58:40 From: George & Debbie Kohl (vienna@cableone.net) I have damaged r.a. spur gears on my lxd75 mount. Can you tell me where I can get replacement gears. Thanks for any help you can give me! George Kohl Show Low, AZMike here: You can try Telescope Warehouse (link on the Astronomy Links page on my ETX Site). But best solution is to contact Meade; depending on the extent of the damage, more might need to be done.
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Thank you for the info. George
Subject: LXD75 out under the stars. Sent: Sunday, May 6, 2007 17:27:29 From: Steve (bullfox@comcast.net) I finally got out to our local darker sky site with the repaired LXD75 and had a great time with it! The goto was working pretty good, although I think the optical axis is a little off. I will work on that next time out. The seeing was not the best, but I put in a 6mm eyepiece anyway, and found the mount to be pretty darn smooth, and a big improvement over the LXD55. At high magnification (333x) there seemed to be an occasional small lurch, although the amplitude was a lot less that what the wind, or my stomping around caused, and about .000001 percent of when I did the kick the tri-pod test. I had Regulus in the 6mm eyepiece and it did wander around a bit but for the most part stayed in the FOV. It was a beautiful night and I was too entertained by the gloriosity of the heavens to do any timings or measurements, so don't have any tracking numbers. The LXD75 is still a bit noisy, in an endearing sort of way. Compared to the LXD55 its kinda like the difference between one of those old washing machines with the wringer rollers on top and one of them new fangled washing machines with the computer and LCD screens. The 75 is defiantly at least 20 better than the 55. Anyway, as the night went along the goto got more inaccurate, probably because somebody kicked the tri-pod several more times, and synchronizing did not seem to help. Which brings me to my question. What I usually try to do is move around the sky in a series of relatively short slews, synchronizing each time. A couple of times, instead of taking the shortest slew to the next target, the mount went all the way around, almost 360 degrees, to the target, which throws it off more than if it just took the shorter slew. So my question is, how can I predict when the mount is likely to take the round about rather than direct slew so I can plan my slews to prevent it?Mike here: I don't know that there is a simple method to predict the AutoStar's movement. Also, SYNCing just improves things in THAT portion of the sky and will make things worse the further the GOTOs are from that location. If you find that things get worse during the night from all the SYNCs, it is better to re-do the alignment.
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I did not realize that about the sync. If I can ever figure out what makes it go all the way around, vs. taking the shorter path, I will give you a report.
Subject: OAG for Meade SN10 Sent: Tuesday, May 1, 2007 20:08:13 From: Thomas Cocchiaro (tomcocchiaro@comcast.net) Just a quick question. Just bought a Meade SN10 (LXD75 UHTC) and it seems that finding accessories for it is almost like finding shoes--I wear size 14. In particular, I'm looking for an off axis guider for it rather than trying to use a guide scope which most experts say is a pain on big scopes because of differential flexure. Trouble is, Meade doesn't make one for it. The Easy Guider Lumicon makes will only work with the 6 and 8-inch Schmidt Newts (according to their FAQs), and still others only work with their proprietary CCD imagers. I want to use my modded Nikon D70. Any suggestions? I know I'm pushing it to try and do astropix on the LXD75 mount (given that the SN10 is a beast on its own without adding another scope), but I don't have the bucks right now to go for the gusto (Orion Atlas, Losmandy G-11 or Titan, Astro Physics 900GoTo, or....Paramount). Any help you could give would be greatly appreciated. Cheers, TomMike here: I am not aware of an OAG for the SN but that doesn't mean that one doesn't exist. As to doing astrophotography with the SN10, that should definitely be doable. A point about the D70, which I also use for astrophotography: focusing is a challenge. I just purchased the Nikon Eyepiece Magnifier for use with the D70 when attached to the Meade Off-Axis Guider and will be testing it out on my next trip to Oracle Observatory. I will report on the results on my D70 (Helpful Information: Astrophotography and OAG (LXD Site) pages.
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Thanks for the note. Let me know how your experiment works out. I bought the $182 Nikon right angle finder from Adorama a while back, and while it makes focusing easier, I'm not all that convinced it would be good on anything other than the moon. The ground glass in the camera makes the image you see in the finder too coarse to determine whether or not stars or distant planets are in focus. Just got back from NEAIC and NEAF this week. The pros say (1) buy and use a Stilleto, (2) focus your lenses (if you use those rather than a telescope) on something close to infinity during the day and tape them down, then use them at night--they say it seems to work (3) use crossed dowels on the front of refector scopes (4) or a Hartmann mask (difficult if you're dealing with dim objects). Don't even try to focus by eye unless it's a last resort. That was the gist of their knowledge contribution. I still can't believe Meade sells the SN10 as an astrophotography platform, with a tripod that's obviously at the max of it's capacity without any add ons, and with no option for an off axis guider. Jerry Londriguss, in his CD book on astrophotography, said don't waste your time with a guide scope on a big tube reflector--it will only cause intense frustration. He added the OAG is the only way to go. Maybe I should beat up on Meade about it, since I'm already doing that in regard to the dec motor that burned up on my new LXD 75 mount right out of the box. Cheers, TomMike here: Results will be posted on the sites. With the magnifier vs the right angle finder, the image on the viewscreen is magnified, which should make it easy to check the focus of a star. I have used a Hartmann Mask in the past but as you noted, it is difficult to impossible to use on faint objects.
Subject: re: RA gear movement on LXD55 Sent: Monday, April 30, 2007 22:14:15 From: richard seymour (rseymour@wolfenet.com) > If I press the left button for say 5 seconds (with speed set to 5), > the RA motor gold gear will turn counterclockwise while I'm holding > the button. When I release the button, the gear will turn back the > opposite way (clockwise) for another 3 or 4 seconds. You didn't mention your Autostar's Firmware version (under Setup/Statistics/[enter][scroll up] However, i think you're seeing the RA Percentage value set too high. (this tells the Autostar how much to back-spin the motors to overcome the backlash you measure by doing a Train Drive). So try lowering that value... perhaps to as low as 1 or zero. good luck --dick
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From: Lamar McLouth (lmclouth@a1isp.net) I think I found what was wrong. After watching the RA gears move, I noticed that the shaft would turn for awhile first then the gold gear (and silver gear) would finally start moving. The set screw on the gold gear had loosened. And since I had trained the drives with the motors in this condition it caused way to much "back-spin". I've now tightened the set screw, updated to 4.3Eg (I was at 4.3Ed), and finally re-trained the drives. It appears to be working well now. Now I just have to wait for some clear skies to give it a "real" test. Right now it's pouring here in Michigan! I will try changing the RA and DEC percentages also. What values do most others use? Thanks for your input and help. LamarMike here: I use the default values on my LXD75. I changed them once when Ihad the LXD55 mount but never found any more satisfactory values so went back to the defaults.
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> I think I found what was wrong. After watching the RA gears > move, I noticed that the shaft would turn for awhile first then > the gold gear (and silver gear) would finally start moving. > > The set screw on the gold gear had loosened. And since I had > trained the drives with the motors in this condition it caused > way to much "back-spin". Mechanical issues can certainly swamp the Autostar's attempt to cover them... > I've now tightened the set screw, updated to 4.3Eg (I was at > 4.3Ed), and finally re-trained the drives. It appears to be > working well now. > > Now I just have to wait for some clear skies to give it a "real" > test. Right now it's pouring here in Michigan! > > I will try changing the RA and DEC percentages also. What values > do most others use? That -really- doesn't matter. Play with them to see what response you prefer. I tend to run mine "low", since i can overcome the lag with a tap of the other slew key, whereas too-high-jerky motion is irritating. On my LX200gps i use 1% for each, for my (very loose gears and bearings) ETX90 i use 10% on the RA, and 15 to 30% (really) on the Looser) DEC. Your mileage -will- vary have fun --dick
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