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Terike
journeyman


Reged: 01/01/11

Re: meade ds-90 new [Re: artao]
      #4294936 - 01/05/11 09:40 PM

I have the same scope and mount setup as you. Though I have a diagonal eyepiece converter to 1.25.

I will be trying to control from the computer very soon. Have you had any problems or do you have any advice that might help me setting it up for my first time?


Clear skies!


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ArieSirius123
super member


Reged: 12/10/10

Loc: wesley chapel, FL
Re: meade ds-90 new [Re: Terike]
      #4294942 - 01/05/11 09:44 PM

best advice is to read the manual for the autostar really. not too difficult to understand after you read it over some.

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ArieSirius123
super member


Reged: 12/10/10

Loc: wesley chapel, FL
Re: meade ds-90 new [Re: artao]
      #4301755 - 01/09/11 01:08 AM

i just wanted to report on this telescope seeing as tonight was the first time i really was able to get it accurately aligned with the goto. i was able to enter anything in the handset and the telescope would find it, and track it, dead on. optics were pretty good too. not as good as a 12 inch dob but pretty damn good for a 90mm refractor. overally very pleased with this telescope. looking forward to getting a 1.25 inch stepback.

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zvaragabor
member


Reged: 01/25/11

Re: meade ds-90 new [Re: artao]
      #4340839 - 01/26/11 05:52 AM

Hi all, I'm thinking of buying a second-hand DS-90. If the objective len is in perfect condition, does it worth a buy? How does it perform compared to a SW or a Cel 90/900? And could someone tell me what's the tube diameter at the focuser end? I've read some comments about the poor focuser design, and that everyone recommends a focuser change, so just to know which size fits in. Any answer would be appreciated. Thanks!

Cheers,
Gábor


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scott m
sage
*****

Reged: 12/06/07

Loc: Hatfield Pa
Re: meade ds-90 new [Re: zvaragabor]
      #4341121 - 01/26/11 09:53 AM

Don't know how it compares to the SW or Celestron but a 86mm focuser fits. I replaced the one on mine with a metal R&P from Meridian.

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zvaragabor
member


Reged: 01/25/11

Re: meade ds-90 new [Re: scott m]
      #4341145 - 01/26/11 10:06 AM

Thanks scott. You use this scope right? Are you satisfied with it? I'm mostly interested in its optical performance.

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ArieSirius123
super member


Reged: 12/10/10

Loc: wesley chapel, FL
Re: meade ds-90 new [Re: zvaragabor]
      #4341346 - 01/26/11 12:00 PM

i have one. its my first scope and i can say that it compares quite nicely to much more expensive scopes ive looked through at star parties. apparently some of them came with .965 eyepiece and some didnt. mine did. and im yet to replace them and even with those eyepieces ive got some awesome views. the goto works pretty good too.

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scott m
sage
*****

Reged: 12/06/07

Loc: Hatfield Pa
Re: meade ds-90 new [Re: ArieSirius123]
      #4341611 - 01/26/11 01:51 PM

Optically it's great very little CA on planets and I think I have had my best views of M42 and the double cluster through this scope.

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sailor70623
Post Laureate
*****

Reged: 01/12/08

Loc: Ok.
Re: meade ds-90 new [Re: artao]
      #4341703 - 01/26/11 02:29 PM

The scope as far as f11 achros goes is fine. Focuser upgrades can help it out a lot. The DS Go-To can work good, but is a bit weak. Make sure it works before you buy. Balance is very important with these units. They do eat batteries. I use my DS Go-Tos with a 12v to 9v adapter and run them off a deep cycle marine 12v battery. The iOptron mounts work a bit better, and the Se mounts from Celestron are much better, but a good working DS mount can be a lot of fun. If you up grade the mount later, these mounts the DS) hold the smaller 60mm scopes just fine. (80mm short tubes too). I have even used them for my 90mm Maks and they work well then too.
The guts on the DS mounts are plastic, and they do break easily. Depending on how much of a DYIer you are, repairs are possible, but not easy. The biggest fown side is that you need power with these mounts. When the batteries are dead, they do not work. Alignment and training and calibration are importabt with these mounts. It can be a challenge for beginners. Once you get the steps down, it's not so bad.


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zvaragabor
member


Reged: 01/25/11

Re: meade ds-90 new [Re: sailor70623]
      #4341904 - 01/26/11 03:34 PM

Thx guys. Sailor, sorry I forgot to mention, it's just the tube I'd like to buy. And the mound would be an eq3. Thank you anyway, useful advice.

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sailor70623
Post Laureate
*****

Reged: 01/12/08

Loc: Ok.
Re: meade ds-90 new [Re: zvaragabor]
      #4341912 - 01/26/11 03:36 PM

Then if it's a good price, go for it.

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scott m
sage
*****

Reged: 12/06/07

Loc: Hatfield Pa
Re: meade ds-90 new [Re: zvaragabor]
      #4342216 - 01/26/11 05:42 PM

I have mine mounted on an EQ3 (Orion AstroView) a little shaky at high power but not bad. I think it has to do with the length of the scope versus the weight of it.

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zvaragabor
member


Reged: 01/25/11

Re: meade ds-90 new [Re: scott m]
      #4344374 - 01/27/11 03:44 PM

Bad news, I was late, unfortunately someone took the telescope. Now looking for another scope... Thanks for all the help.
Cheers


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wagner lip
sage


Reged: 01/12/11

Re: meade ds-90 [Re: zvaragabor]
      #4347358 - 01/28/11 08:19 PM

Last week I bought a DS-90 with the Autostar #494, diagonal and eyepieces are 1.25". I went to pick it up with the seller almost 3 hours from home here in Florida.

I disassembled everything, cleanned everything with warm soappy water and soft brush and cloth as it should. No kidding, disassembled even the main lenses and the guts of the 9mm eyepiece that came along, with extra care, distiled water with small quantity of windex. Fingerprints on the lenses are not a good thing, but I was able to clean everything without compromising the coatings. Ended up pristine clean.

Believe of not, the mount legs were never extended.

The #492 motors units (gears, shafts, photosensor) went through a special care, wash and clean up. Everything was in good shape, but mechanically out of alignment everywhere.

Replaced some washers and nylon retaining nuts on the worm/gear units with brand new ones from Ace Hardware, now they are working like a violin.

I noticed that some people complain about large backlash on DS motors, the problem is mostly adjustment on the worm/gear pressure and worm axial slack movement, easily reduced by the nylon retaining nut adjusment. The worm shaft has a type of conical slug in the opposite side of the nut, if the nut is not correctly tied, the conical slug doesn't go correctly into his bed and the worm ends up with larger distance from the gear... large backlash.

There is a mechanism to fine adjust the distance from the worm to the gear, it is at the nut side of the worm's shaft. It is a kind of bed elevator for the shaft, in the form of a black nylon nut, it pulls the worm's shaft against the gear, adjusted by a tiny alen screw locked by a small nut at 90 degrees to the shaft. The adjustment should be done only after everything else is adjusted (mostly the conical slug in the correct place) and lubed.

A common mistake is to apply grease in the clutch, between the gear and the large locking washers on each side of it. If you do, you will need to apply more force on the knobs to lock the scope (clutch) to the motors. Just wash the gear and the washers in warm or hot soappy water to remove any grease, use a toothbrush to help. After dry, apply a narrow white lithium grease on the gear teeth band and over the worm and that's it. You can apply lithium grease on the support plastic bearings of the worm shaft.

The DS-90 tube is heavy, large mass, the #492 motors are not that strong for this brute, lacks muscle, so tube balance should be pristine. Because of the mass of the scope, the motors will consume more power than most of the other DS scopes. For that I don't use regular AA batteries. I use a power adapter (12V @ 2A) or a 12V@7A Powersonic Lead Sealed battery underneath the mount, or tied to a tripod leg.

Found the plastic encasing the worm/gear underneath the mount base with 3 to 4mm of slack to the base (horrible backlash), like if it was with loosen screews, even so the 3 screws that hold it underneath the mount base where tied. Removed everything, clean, glued a thin silicon band (rubber band should do the trick) in the grove (on the plastic case) that touches the underneath of the mount base. Upon assembly it is now solid. It should had a "O-Ring" or some grooves to avoid it being only hold the plastic case by the tiny screws. With the constant force of the motors back and forth, and friction, the screws openned a wider hole in the plastic, causing the problem. The silicon/rubber band will solve it for years.

The Autostar Computer Controller #494 was telling me some motor problems upon power up. Google told me it could be several things, including bad connection on the coiled cable. Measuring continuity between the RJ31 connector and the inside connector of the #494, found the green wire (pin #4 or #5 on the RJ31) with no contact. Just use the RJ45 crimp tool to recrimp the RJ31, and bam! working like a charm.

The output gear of one #492 motor has one tooth with a small damage. From time to time it skips a step. I am already shopping for a gear replacement. As a matter of fact I am requesting 2 extra #492 motors for safe future, Meade is not manufacturing those any longer.

The DS-90 has fantastic optics, simple, clean, clear and easy, nice light. The viewpiece of 9mm gives around 110x magnification, you can see an orange vertical band on Jupiter, and Saturn is like a little white bird sliding in the black sky, will be stuck in my mind forever.

Aperture of 90mm (3.5") is not that much, but make wonders. This kind of scope really needs a TELRAD urgently. The viewscope that comes with it is a total waste of time.

The AutoStar unit works very well in this unit.

You *MUST* setup the AutoStar controller with your correct Lat/Long (or city), and perfect Date/Time (and DayLight Savings info). Date and Time is required at each power off/on.

Then you need to do the inicial physical setup, very nice horizontal alignment with the tripod and scope. Use a couple of good round (360 degrees) bubble levels, one for the mount and legs, another for the scope itself, then point everything (horizontally) the best you can to the sideral north. Then proceed with the two stars alignment. After that, things works very nice most of the time.

The original focuser has some small vertical slack, but not a problem if you use the #494 and motors to fine adjustment of position.

I have severe back pain. It seems that all refractor scopes are no good for people like me. As the pivot point of the mount goes in the middle of this 40 inches scope, any lateral or vertical move will require you to do the same on the eyepiece. After 90 minutes of playing outside, my back was killing me. I am not that athletic anymore.

I will hate to depart from this DS-90 unit, but it seems the obvious path for my back sake.

The DS-90 is an impressive unit, it is not small, it has personallity and size. People look at it and say "wowa, for sure this is not a toy".

This week I was able to find a ETX-90EC with lots of bells and whistles. With much less movement on my side, my back is already thanking me.

Of course I am still waiting HayNeedle to deliver the second box of my brand new CPC800. The scope itself is in the box here waiting the mount and power bucket that are on backorder from Celestron.

In some way I need two scopes, this way I am trying to have my teen-18-ager boy along me on those Saturday cold nights. Yeah right! At least after he returns home late night!

Edited by wagner lip (01/28/11 08:20 PM)


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rdandrea
Carpal Tunnel
*****

Reged: 06/13/10

Loc: Colorado, USA DM59ra
Re: meade ds-90 new [Re: wagner lip]
      #4347386 - 01/28/11 08:39 PM

Good, thorough post. Thank you.

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mexjon
Poet Laureate
*****

Reged: 12/01/10

Loc: Florida - Yucatan, Mexico
Re: meade ds-90 new [Re: wagner lip]
      #4347439 - 01/28/11 09:14 PM

Wagner- Very informative post! Now that you have that ETX90 EC, make sure you do the same good cleaning job to the right friction clutch so yours doesn't end up broken like mine. Apparently previous owner(s) had over-tightened instead of cleaning and sanding the right tube adapter as they should have. Probably had a lot of grease preventing friction, and they just kept tightening away. By the time I got it, most of the damage was done and it soon broke on both sides of the clutch.

Thanks for your thorough report on your DS. I enjoyed learning about it.

Cheers


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wagner lip
sage


Reged: 01/12/11

Re: meade ds-90 new [Re: mexjon]
      #4353350 - 01/31/11 02:56 PM

John, yesterday I disassembled the ETC90-EC, clean, sand, adjust, lube. It was a nice task. I am posting the work in a new thread, including some pictures of the fork motor noise reduction trick and sealed lead acid battery support.

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mexjon
Poet Laureate
*****

Reged: 12/01/10

Loc: Florida - Yucatan, Mexico
Re: meade ds-90 new [Re: wagner lip]
      #4353403 - 01/31/11 03:23 PM

Quote:

John, yesterday I disassembled the ETC90-EC, clean, sand, adjust, lube. It was a nice task. I am posting the work in a new thread, including some pictures of the fork motor noise reduction trick and sealed lead acid battery support.




Very good. Avoiding a major problem by getting all that done. Hope you enjoy it.


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artao
super member


Reged: 10/06/10

Loc: SW Wisconsin
Re: meade ds-90 [Re: mexjon]
      #4355021 - 02/01/11 07:53 AM

@Wagner -- thanks for all that info, i'll have to take mine apart and check those adjustments. I do have a backlash problem on both axes, which seems to exist IN the mount, not the gearpack. I've read of "the leather washer fix", but am having difficulty re-locating that info. Do you, or anyone one else, know anything about this??
Also, regarding your disassembly and cleaning of the main optics ... how difficult was it to maintain collimation? Is the lens assembly sensitive to rotational collimation as well?


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mexjon
Poet Laureate
*****

Reged: 12/01/10

Loc: Florida - Yucatan, Mexico
Re: meade ds-90 [Re: artao]
      #4355937 - 02/01/11 03:27 PM

Quote:

@Wagner -- thanks for all that info, i'll have to take mine apart and check those adjustments. I do have a backlash problem on both axes, which seems to exist IN the mount, not the gearpack. I've read of "the leather washer fix", but am having difficulty re-locating that info. Do you, or anyone one else, know anything about this??
Also, regarding your disassembly and cleaning of the main optics ... how difficult was it to maintain collimation? Is the lens assembly sensitive to rotational collimation as well?





I read on Google that the leather washer info is on the Yahoo DS Group.


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