Celestron G-3 [C90]

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Brand and Model:Celestron G-3 [C90]
Price ($USD):$500
Type:Maksutov-Cassegrain
Attributes: un-checked Go-To un-checked PEC
Aperture:90mm (3.5")
f Ratio:f/11
Focal Length:1000mm
Finder:8x20
Electric Power:4xD-cells
Mount:GEM
Tripod:CG-3 GEM Mount
Weight (lbs):17 lbs lbs.
Dimensions (w/h/d):
Description:Helical [camera-style] barrel focus.

Close focus:4' to infinity [lots of focal tolerance!]



If enhanced with a 1.25" vis back and Large accessory ring [LAR], this scope is

on-par with the ETX in image quality.

Vote Highlights Vote
Celestron G-3 [C90]
I have this scope, and have changed it to an LAR with Lumicon diag., changed finder to 6 x 30 and added a Rigel.

Mine is the starbright, rubber coated one. I use it with Ultima EP's. I also have a C5 & C8 SCT. With the C90 on good viewing I can go upto 250X, most nights at least 200X. Resolved M13, split the double double, and have seen most of the M's. I take it on birding trips where it doubles as a great spotting scope and close focus nature scope during the day, and on my photo tripod at night for a scope.

I you want a great little scope for little money buy one of these off one of the used sites (should be about $200 in great shape, if it doesn't have the LAR make sure you get one and use real 1.25" diagonal).

Small size, good optics, and very rugged. Had mine for 10 years and will keep it as it is so versitle and so small.


Also, relube it (screws to seperate the two parts on are behind the tripod mount under the rubber) with good grease (be very careful), and you find that it focuses smoothly.

Overall Rating: 9
Optics:9 Ease of Use:10 Value:10
Weight: 1 (Unreliable Vote)
Date:
By:
Link to this vote: https://www.excelsis.com:443/1.0/displayvote.php?voteid=486230

Celestron G-3 [C90]
I have an older model c-90 orange tube. It has good optics
and like someone else posted its top magnification is rated
at 200x. It does not have the sleek looks of the meade etx but it is just as good. factoring in the cost, and construction I feel it is a goog instrument to use.

Overall Rating: 10
Optics:8 Ease of Use:9 Value:8
Weight: 1 (Unreliable Vote)
Date:
By:
Link to this vote: https://www.excelsis.com:443/1.0/displayvote.php?voteid=129617

Celestron G-3 [C90]
What a great daytime and nightime scope. I have the C90 version and knew going into this that in order to improve the performance of this little gem of a travel scope all you have to do is...

a) Replace the LAR back from the .965 to a 1.25 back...

b) Toss out the cheap diagonal Celestron bundles with this scope...

c) Use some decent eyepieces (which is true of all scopes, decent eyepieces do make a difference on any scope).

I did all three...changed out the LAR, purchased a Lumicon 1.25 diagonal (wow what a difference there) and used some Televue and Celestron Ultimas! This is like a *entirely different* scope now. Why Celestron doesn't just set this up for 1.25" eyepieces to begin with is beyond me?

Anyway, the views are spectacular, planets, double stars, even some deep space. For a small compact scope this delivers. I purchased the Celestron case for this as well as the Celestron deluxe slow-mo device that attaches to a tripod. This now goes with me when I travel for pleasure or to visit friends and relatives.

I recently purchased a 1.25 Meade 45 degree erect image diagonal for my daytime use but have yet to test it out. I am sure this will likewise be a big improvement over the .965 gear that unfortunately comes with this gear.

As for the focuser (which another individual above complained about...once you get used to it is not that big a deal. Once an eyepiece on this is focused it is focused. I am sure much of the complaints on this scope come from individuals who have not changed out the LAR back to accomodate 1.25 eyepieces, and from not getting rid of the junky diagonal that came with it. A Lumicon, Televue or INTES diagonal will make this puppy sing...and if you put in some decent eyepieces it will do a dance as well.

Bottom line...if your looking for a small, lightweight, easy to use telescope or daytime spotting scope...this can fit the bill...*IF* you make the apporpriate economical changes necessary to improve this scopes performance.

Overall Rating: 9
Weight: 1 (Unreliable Vote)
Date:
By:
Link to this vote: https://www.excelsis.com:443/1.0/displayvote.php?voteid=39336

Celestron G-3 [C90]
I HAVE THE C-90 ASTRO VERSION. THE OPTICS ARE SHARP FOR ASTRO USE IT'S REAL STRENGTH IS THAT OF A DAYTIME SPOTTING SCOPE. WHEN COMPARED TO A MEADE EXT THE EDGE WOULD GO TO THE ETX. THE ETX HAVING A LARGER PRIMARY MIRROR AND SMALLER CENTRAL OBSTRUCTION. AS FOR THE MOUNTING THE C-90 WITH ITS SINGLE FORK ARM MOUNT IS CLEARLY SUPERIOR.
I HAVE USED THIS TELESCOPE VIEWING SOME OF THE BRIGHTER MESSIER OBJECTS WITH GOOD RESULTS. ONE AREA THAT THIS TELESCOPE EXCELS IN IS WHITE LIGHT SOLAR OBSERVING,UNDER GOOD SEEING CONDITIONS.THE BEST FEATURE OF THIS UNIT HAS TO BE IN ITS PORTABILITY AND EASE OF USE.

I GIVE IT A RATING OF 9

Overall Rating: 9
Weight: 1 (Unreliable Vote)
Date:
By:
Link to this vote: https://www.excelsis.com:443/1.0/displayvote.php?voteid=39335

Celestron G-3 [C90]
I've been using a rubber armored one with a simple equatorial from astronomics. The big problem has been the lack of a good diagonal. Finally I tried an Apogee prism diagonal- it was like getting a new telescope. I discovered the plastic hybrid diagonal vignettes the image. Without it, a 40mm plossl can show all of the Pleiades. Celestron, dump whoever is making those plastic hybrid mirror diagonals and include something better. I also found and corrected another flaw- the front of the baffle is matte and not flat back, and so it throws up a lot of glare in images of bright objects (point the telescope to the side of a lamp and look in the cell and you will see a bright doughnut around your eye from the baffle). A little flat black acrylic model paint and presto- ultra hign contrast images. Use care when doing that, thoug. I used a pipe cleaner (wash it well first with dish detergent) and practiced the motions needed to paint the baffle several times before trying it with paint. Also, hold the telescope when you do this so if it does drip, it will just land in the barrel (it's better to use the proper amount of paint). I am now able to make out the Cassini division on Saturn on clear nights. THe only problem with this is I'm distressed to think of how many people have been discouraged with this scope because of a lousy diagonal and a baffle defect. I've been able to make a primo glare/ dew cap with a piece of corrugated 4" lawn drainage pipe from home depot. The bell mount on one end appears to be a perfect fit for the C90's rubber armor. Just paint it flat black and it looks like it was made to go with it. The corrugated part should be about 6" long past the end of the telescope after you cut it to fit. The other benefit is the corrugations slow air flow so it doesn't dew-up even in summer in the south.

I love it as a quick look scope. The tube is so short that popping in and out of doors is easy without hitting anything. I've gotten around the cool-down problem by putting it in the refrigerator if I think I might do some viewing (hey- it's small!). All in all, it's fun to play with- there's a lot of stuff I've done with it already I'd never think of trying with a $2000 APO.

Things to try:

Hit the great nebula and go up to about 80X- surprise! Even in the city, the region around the triapezium will have wings.

Get a 40mm plossl, head to the countryside, and find double cluster- absolutely fabulous in this tube.

Planets- the look best somewhere between 80X and 133X. The main stripes on Jupiter are obvious.

Stars: Yes, it will split the double double, but try this: Go to Sirius when it is near the horizon- sometimes atmospheric effects make it incredibly colorful.

Airplanes- try tracking one!

The moon: Use a low power lens and project it on a piece of paper shaded from the moon (as if you were doing solar projection) Note: Whatever you do DO NOT point a C90 at the sun unless it has a specially made mirrored solar filter over the front.

Most of all- remember to take it out now and then. I'd suggest keeping it even if you get a bigger tube. If you do, this can serve as a bang-around scope, or a sky checkout for seeing if conditions are good enough to bother with the big tube.

Overall Rating: 9
Weight: 1 (Unreliable Vote)
Date:
By:
Link to this vote: https://www.excelsis.com:443/1.0/displayvote.php?voteid=39334

Celestron G-3 [C90]
The focusing mechanism kills it, I can never get good focus. Focus it may easily move your target out of sight as well. Image breaks down completely, well before 200x which is easy with smaller refractors. Cool down time is quite long, but once cooled down, the scope performs quite nicely. This kind of small scopes are supposed to be used for quick looks, but the relatively long cool down time is not suitable for this purpose.

Overall Rating: 7
Weight: 1 (Unreliable Vote)
Date:
By:
Link to this vote: https://www.excelsis.com:443/1.0/displayvote.php?voteid=39333

Celestron G-3 [C90]
With the LAR and high quality Mirror Diagonal this is a great travel scope. Cleanly split the dbl dbl with a 10mm. Resolved M15 with the 10mm and a barlow (about halfway). Is a very good telephoto lens. Can take about 200x on a good night. Very well built for a travel or quick look scope.

Stable on an old skyview deluxe, also works good to very good on a bogen 3001 with fluid head.

Ok for DSO's with M type brightness.

You can not find a better nature scope - focus down to 5' -

Overall Rating: 9
Weight: 1 (Unreliable Vote)
Date:
By:
Link to this vote: https://www.excelsis.com:443/1.0/displayvote.php?voteid=39330

Celestron G-3 [C90]
Great little scope! Provides pleasing views of the planets and brighter deep-sky objects. Rugged construction except for the plastic diagnal, which I replaced. The finder was ok, but I prefer the non-magnified "red dot" or Telrad type finders (which I have upgraded to as well). The focuser takes a little getting used to, but works fine once you are used to it. The equatorial mount is plenty stable for this size of scope, and the motor drive works great for visual observing, though I wouldn't reconmend it for photography. Sure, the C90/G3 is not as good as 3-4" scopes costing four times as much, but that's true with about any scope in this price range. When considering size, price, and performance, the G3 is a fine scope.

Overall Rating: 9
Weight: 1 (Unreliable Vote)
Date:
By:
Link to this vote: https://www.excelsis.com:443/1.0/displayvote.php?voteid=39329

Celestron G-3 [C90]
I bought one of these (spotting scope version) on a pirat mount in 1978. It was absolutely the worst telescope I ever owned, failing to provide usable images at 50x power. Junk!

Overall Rating: 1
Weight: 1 (Unreliable Vote)
Date:
By:
Link to this vote: https://www.excelsis.com:443/1.0/displayvote.php?voteid=39327

Celestron G-3 [C90]
I too purchased a G-3 from Astronomics for 399. Unfortunately I was quite disappointed while side by side work was done with a tv-85. It was like night and day with similar aperature. I could not split Rigel when the Tv-85 was a clear clean split etc etc. The finder was useless with no upgrades or accessories available. We won't comment on the little plastic diagonal...I was scared it would not support some 1 1/4 pieces. I was disappointed in the views of basic clusters in comp. to the 85 and finally when we put them together on another night and viewed Jupiter and Saturn.....ugh....it was ugly. The 85 was as if from a textbook, and mine was as if .........Sorry. I sent it back and bought an 85! Oh, I forgot (if as if I have not said enough)...the helical focuser is impossible to use without totally jiggling the entire scope making it next to impossible to focus. P.S.....I love the 85!

Overall Rating: 5
Weight: 1 (Unreliable Vote)
Date:
By:
Link to this vote: https://www.excelsis.com:443/1.0/displayvote.php?voteid=39326

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