20 replies to this topic

[snovak]

Hey everyone!   Like many people, I got laid off from the pandemic and I am looking for things to do at home and outdoors and noticed a few telescopes that popped up on Craigslist.  I started looking at the ads but really didn't know what was a fair price or a good place to start.  I decided since I live in a major city, that I really wanted something that would pack quickly and safely into the truck and I could take out into the wilderness to use.  A bit of research and it seemed like the Meade ETX-90 was a good place to start.  I was excited to see a Meade ETX-90 that was listed for $300 on Craigslist, so I quickly went to go check it out.

 

Sadly, it turns out that the owner was given this when they were 7 years of age, and this is the original ETX-90 without the hardcase, tripod, and "Go To" features.  On the plus side, I was told that his dad and him used it only a handful of times and it had been sitting in the original box for the last two decades.  It certainly looked very clean and the box didn't have any major damage or dust inside it.  It had decided I was going to pass on it and but they offered it to me for $160.  I'm not sure if that was a fair, good, or great deal, hopefully not bad, but I took it. 

 

So now I have this ETX-90 telescope in the original cardboard from 1996(?) with a Celestron PLOSSL 12.5mm objective, a Meade PLOSSL 26mm LP multi-coated objective, and lastly a Meade 2x Barlow 1.  Everything looks really clean with no flaws in the lenses with the exception of the Barlow.  It looks like the multicoating on it might have gotten rubbed off? The OTA itself looks brand new with the paint looking flawless and glittery.  The reflector didn't have any dust on it, and the tube looked similarly free of anything.  The end cap was on it and the front collector was perfectly clean and flawless.  So optically, I think I have a good tube and some objectives.  The only think I'm worried about is that it only has 2 of the 3 legs and I'm afraid it might have batteries that could have leaked inside the base.  Crossing my fingers and will have to open it up tomorrow.

 

Since I'm not going to have the "Go To" options, what would people suggest I get for star charts and learning how to use them?  I'm assuming that there are Android Apps or applications for your PC that you can use, or maybe just a website?  Is there anything I should get or do as immediate things to make this older tool work better today?

 

Cheers

-S

[UT_JimW]

This was my first scope. My late father gave it to me as appreciation for all the help I was giving him. Sadly, we bought one of the last RA scopes off the line before the go-to came out. That kind of bugged me, but the scope has special appeal because of my father.

My first view (tiny but there) of a Martian ice cap was thru this scope sitting on a porch of a cabin at 8800 feet.

Good luck on the base - I hope the battery compartment is clean. I eventually screwed up and left some in and that got my base. I eventually got a go-to base, but have to finish swapping over. If worse comes to worse you could dismount it from the base and use other mounts.

The views of the moon through this scope are exquisite. I've moved up to an ETX125 for Jupiter, but the 90 will get you started.

I've never used my legs - I've generally mounted it to a heavy tripod.

One of the best investments I got for mine was a solar glass filter. It's a great sun spot scope with that. We used it to watch an annular eclipse and the 2017 total eclipse. The view during totality when the filter could come off was incredible.

With the 45 degree diagonal it makes a great spotting scope. Watch for a used one here on CN.

Your eyepieces will get you started. I like the 26mm plossl. I don't have great eyepieces but have started picking up some used mid-range. I like a TeleVue 32mm plossl and a 12.5mm Radian. A Siebert 9.9mm I got pretty reasonably on CN has worked well on Jupiter. CN reviews can help you decide on ones to try..

Enjoy your scope. If you put it to good use, that $160 will seem like a good investment over the years!

Jim

[UT_JimW]

Oh, forgot to mention. The small star atlas from Sky and Telescope has been used more than my big one, but lately I've just been using Sky Safari 6 (I have the ios version). It was recently on sale for $6.99 due to the meteor shower.

[Cometeer]

$160 is not a bad price. The two original ETX 90s I’ve owned had amazing optics. 
 

There’s no need for the paid versions of Sky Safari. The free version has a great star chart and should suffice. 

[JohnBear]

I believe the table top tripod legs for all ETX 90s have 1/4' -20 threads. So you can just go to the hardware store and get a short piece of threaded rod to use as the missing leg - Cut it the right length for your latitude and put a little end cap on it - and done. That is what I will be doing for a 90 EC that I am assembling from used parts.

 

Battery compartments can be cleaned up if needed. It probably has an external power jack - if so get a 12V adapter for it - and maybe a li-ion Talentcell battery from Amazon.

 

If it is that clean and optically good, it should be well worth what you paid, and I am sure you will get a LOT of enjoyment out of it. 

Edited by JohnBear, 14 August 2020 - 04:28 PM.

[JamesDuffey]

You can get an original set of legs at Telescope Warehouse:

 

< https://telescope-wa...s-etx-70-etx-90 >

[RAK on Tour]

Another thing to check is the baffle around the reflective spot on the front meniscus. On the original ETX-90, which you have, the baffle can slide to one side, especially if it has been stored on its side. There are a number of fixes for this.

 

Roger

[grif 678]

I have one of the older ETX 90 OTA's, without the base or legs, the only way to go. I put mine on a unitron 114 altaz mount, the one for the 60mm unitron. To me, and what I have read from others also, table top tripods are not very stable and easy to use ways to view. Being on the simple, sturdy, and light weight unitron mount, it can be carried out with one hand, and can be viewing in 30 seconds. The optics on this 90 ETX are remarkable for a 90mm. I keep it on the tripod, and it is ready to go out in seconds. I am pretty sure that you will not like the table top tripod legs, even the Questar owners put theirs on a good tripod, from what I see in pictures etc. I think you will be very satisfied with the optics, if they haven's been jarred out of collimation or something like that, and having a good tripod will enhance your viewing pleasures a lot.

[GEC]

I have one (ETX90 RA) that I bought new and have used it as a grab n go.  I used it to sketch for the Mars oppositions on '99, '01, '03, and '16. (along with a 7" Mak, and a C8).  Since the 2018 opposition, I have used the MC127 when travelling, but it still gets used.  It has very fine optics and puts up a great image. 

 

While the optics are great the old non-goto mount was rather a pain to use and required several work arounds.  My advice is to ditch the mount and put it on a newer goto. They can be found at reasonable prices.  I put mine on an old used celestron nexstar GT that I got on ebay.  Works great.  The scope is very light and small.  Like Grift I keep  mine set up on a home made tripod and can carry it out to the yard and set up very fast.  I plan to keep it forever.

 

cheers

GEC

[TSparky]

I just picked up one of these for a song.  It was missing the eyepiece set screw and based on other posts I picked up some M3 screws.  They didn't fit so i got a selection of M2-M5 nylon screws and they don't fit either.  What size is the screw?  Is it a US thread?

 

Thanks

TSparky

 

[dusty99]

Congratulations on your EXT, and welcome to CN!

[JohnBear]

After tuning and rebuilding the mount for the ETX90EC that I parted together, I took it out for a real first light two night ago - It was very good atmospheric seeing. and boy was I was duly impressed with the optics.  I was watching the the GRS AND  a moon shadow transiting Jupiter, and it was as good an image of Jupiter as I have seem with my 8" Dob.  I hope your '90 does equally as well. 

[mitsos68]

Another thing to check is the baffle around the reflective spot on the front meniscus. On the original ETX-90, which you have, the baffle can slide to one side, especially if it has been stored on its side. There are a number of fixes for this.

Roger

[mitsos68]

Hi. I have this issue. How can I fix it?
Regards
Dimitris.

[RAK on Tour]

Hi. I have this issue. How can I fix it?
Regards
Dimitris.

I have read several owners say they have unscrewed the front meniscus (this doesn't affect collimation) and then pull the baffle off carefully. You may need to keep dabbing at any remaining adhesive to get it all off. Be sure to use the baffle and adhesive that came off with it to do the dabbing. Be careful not to scratch the reflective spot on the meniscus. 

 

Once everything is is off that reflective spot, remove all the old adhesive from the baffle. You then need a new adhesive to reattach the baffle. I'm afraid I don't know what adhesive to use, but I know that Meade doesn't have any of the original adhesive rings. Be sure to use an adhesive that doesn't out-gas and fog the reflective spot. Once the adhesive has dried, screw the meniscus CAREFULLY back onto the optical tube.

 

IF YOU ARE VERY PATIENT, another method to realign the baffle is to store the ETX on its side with the baffle on the upside of the reflective spot. It could take a year for the baffle to slide back to center, so this isn't a quick fix by any means. Always store the optical tube vertically after the baffle is centered. 

 

I have two ETX-RA's, one of which has an off-center baffle. So far, it hasn't recentered itself, though I have read of other owners that had success by letting gravity fix the misalignment.

[mitsos68]

I have read several owners say they have unscrewed the front meniscus (this doesn't affect collimation) and then pull the baffle off carefully. You may need to keep dabbing at any remaining adhesive to get it all off. Be sure to use the baffle and adhesive that came off with it to do the dabbing. Be careful not to scratch the reflective spot on the meniscus. 

 

Once everything is is off that reflective spot, remove all the old adhesive from the baffle. You then need a new adhesive to reattach the baffle. I'm afraid I don't know what adhesive to use, but I know that Meade doesn't have any of the original adhesive rings. Be sure to use an adhesive that doesn't out-gas and fog the reflective spot. Once the adhesive has dried, screw the meniscus CAREFULLY back onto the optical tube.

 

IF YOU ARE VERY PATIENT, another method to realign the baffle is to store the ETX on its side with the baffle on the upside of the reflective spot. It could take a year for the baffle to slide back to center, so this isn't a quick fix by any means. Always store the optical tube vertically after the baffle is centered. 

 

I have two ETX-RA's, one of which has an off-center baffle. So far, it hasn't recentered itself, though I have read of other owners that had success by letting gravity fix the misalignment.

Thank you Sir!

[oldmanastro]

Congratulations on acquiring the ETX-90. It is an excellent telescope with very good optics and quite portable. I have an ETX-90EC that is now 20 years old and in perfect condition. It has never lost collimation. Originally it used the Meade Autostar 497 goto system but after going through two hand controllers I decided to run it with the standard hand controller. The telescope will give you great views of the moon and planets and contrasty views of the deep sky. It's limited just by aperture. Apparently the sliding baffle problem was resolved in later models. I have never observed my baffle out of place even in this very hot climate. 

 

  I recommend that you visit this website. It has loads of information about the ETX-90.

 

http://www.weasner.com/etx/menu.html

 

 

Clear Skies!

 

Guido

[mattyfatz]

I just picked up one of these for a song.  It was missing the eyepiece set screw and based on other posts I picked up some M3 screws.  They didn't fit so i got a selection of M2-M5 nylon screws and they don't fit either.  What size is the screw?  Is it a US thread?

 

Thanks

TSparky

 

DSC_6620 small.jpgDSC_6621 small.jpg

The set screw is an M4. 7mm long

if you already tried that size, the threads are probably jacked up. Just retap them.

Edited by mattyfatz, 23 August 2020 - 08:54 PM.

[LU1AR]

A restored one; and I fixed the RA motor speed and torque, as well as the looseness of the table legs.

 

https://www.cloudyni...etx-90-upgrade/

 

Clear skies.
Edgardo

[latentfuss]

I have read several owners say they have unscrewed the front meniscus (this doesn't affect collimation) and then pull the baffle off carefully. You may need to keep dabbing at any remaining adhesive to get it all off. Be sure to use the baffle and adhesive that came off with it to do the dabbing. Be careful not to scratch the reflective spot on the meniscus. 

 

Once everything is is off that reflective spot, remove all the old adhesive from the baffle. You then need a new adhesive to reattach the baffle. I'm afraid I don't know what adhesive to use, but I know that Meade doesn't have any of the original adhesive rings. Be sure to use an adhesive that doesn't out-gas and fog the reflective spot. Once the adhesive has dried, screw the meniscus CAREFULLY back onto the optical tube.

 

IF YOU ARE VERY PATIENT, another method to realign the baffle is to store the ETX on its side with the baffle on the upside of the reflective spot. It could take a year for the baffle to slide back to center, so this isn't a quick fix by any means. Always store the optical tube vertically after the baffle is centered. 

 

I have two ETX-RA's, one of which has an off-center baffle. So far, it hasn't recentered itself, though I have read of other owners that had success by letting gravity fix the misalignment.

I used command adhesive to fix mine. I cut tiny little strips and I'm very happy with the result

[DennyD]

I got an original ETX90 RA last year. Turns out it hadn't been used, as the 26mm plossl eyepiece was still sealed in the bag. I replaced the stock viewfinder with the Meade 90° version for the ETX 125. The baffle on the secondary had moved like yours. I removed the meniscus and sent it to Bill at Telescope Warehouse for repair (I think the cost was $25 plus shipping). He also has the table top legs in stock. I also got some Meade Super Plossl eyepieces and the #883 tripod. Great telescope.