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Cometron CO-62

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#1 LDW47

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Posted 21 September 2019 - 02:17 PM

What are the expert thoughts on a Celestron Cometron CO-62, f4.8 from the mid 80’s as a fun to have / use refractor ? Are they reasonably built, what are their good / bad points ?



#2 grif 678

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Posted 21 September 2019 - 03:42 PM

Never owned one, but with that short focal length, there has to be a lot of color on the brighter objects. Would make a good day time spotter I would think.


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#3 mtminnesota

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Posted 21 September 2019 - 04:02 PM

I had one for a while, and used it as a spotting scope only.  It only cost $99 new, with tabletop tripod, diagonal, finder, and one or two eyepieces, so I didn't expect much, but I was pleasantly surprised at the build quality.  It was made by Vixen, so it wasn't junk.  Here's a thread on it:  https://www.cloudyni...cometron-co-62/


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#4 LDW47

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Posted 21 September 2019 - 04:22 PM

Never owned one, but with that short focal length, there has to be a lot of color on the brighter objects. Would make a good day time spotter I would think.

Thanx ! I’m not a brighter objects ie moon, planets type guy any way, I want it for my Bortle 1 skies at my camp. But I thought for the price what the heck, it will be fun.



#5 russell23

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Posted 21 September 2019 - 05:03 PM

I had one and it was just fine at ~15x for a nice wide field. I wouldn’t bother with much more than that. The 18.2mm DeLite worked well with it.
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#6 Jon Isaacs

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Posted 22 September 2019 - 08:47 AM

I had one and it was just fine at ~15x for a nice wide field. I wouldn’t bother with much more than that. The 18.2mm DeLite worked well with it.

 

I bought David Russell's Cometron 62mm.  The build is solid, the optics disappointing... I measured the effective aperture using an expanded beam and found it to be about 55mm.  The low power views were OK but anything more was quite poor, It's a cemented doublet, no chance to try to adjust it.

 

I ended up giving it to someone who wanted one for nostalgic reasons. 

 

Jon 


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#7 LDW47

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Posted 22 September 2019 - 09:47 AM

I bought David Russell's Cometron 62mm.  The build is solid, the optics disappointing... I measured the effective aperture using an expanded beam and found it to be about 55mm.  The low power views were OK but anything more was quite poor, It's a cemented doublet, no chance to try to adjust it.

 

I ended up giving it to someone who wanted one for nostalgic reasons. 

 

Jon 

Thanx, I kind of knew what I was getting after doing some research but most people had good things to say about something, lets face it, that is a small, cheap but a well built scope. I have always wanted one of these, more than a toy, scopes and I think it will be fun to try, to play with under the black skies at my camp. I too know some to pass it on to, at some point !


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#8 Jon Isaacs

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Posted 22 September 2019 - 10:01 AM

Thanx, I kind of knew what I was getting after doing some research but most people had good things to say about something, lets face it, that is a small, cheap but a well built scope. I have always wanted one of these, more than a toy, scopes and I think it will be fun to try, to play with under the black skies at my camp. I too know some to pass it on to, at some point !

 

I'd always wanted try one as well. Maybe yours will be better than the one Dave and I had. 

 

Jon


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#9 Jim7728

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Posted 22 September 2019 - 10:17 AM

I'd always wanted try one as well. Maybe yours will be better than the one Dave and I had. 

 

Jon

Came this close to buying one I saw on display in the Commissary at Fort Bliss  in early 80s during basic training.  Would have been an upgrade to my Selsi 40mm table top zoom, though I did see moons of Jupiter with it. laugh.gif

 

Cometron might be fun with a 24mm Panoptic.


Edited by Jim7728, 22 September 2019 - 10:18 AM.

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#10 Jason B

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Posted 22 September 2019 - 12:26 PM

I have 2.  Bought the 1st one as I always thought they looked cool in the old Celestron / Cometron catalogs.  Used it for film ap a little, it was ok, tons of color etc.  Works ok for low power views, ok spotter too.

 

Don't really remember why I got a 2nd but they do make good guidescopes too as they do have a solid focuser that locks.



#11 agmoonsolns

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Posted 22 September 2019 - 03:40 PM

All you have to do is change the baffles to get the full 62mm of aperture. By doing that and making sure the lens is properly collimated, you end up with a really super little scope. These scopes perform MUCH better when you do that. I tweaked and adjusted mine to perfection.

 

I bought David Russell's Cometron 62mm.  The build is solid, the optics disappointing... I measured the effective aperture using an expanded beam and found it to be about 55mm.  The low power views were OK but anything more was quite poor, It's a cemented doublet, no chance to try to adjust it.

 

I ended up giving it to someone who wanted one for nostalgic reasons. 

 

Jon 


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#12 LDW47

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Posted 22 September 2019 - 04:17 PM

All you have to do is change the baffles to get the full 62mm of aperture. By doing that and making sure the lens is properly collimated, you end up with a really super little scope. These scopes perform MUCH better when you do that. I tweaked and adjusted mine to perfection.

Hopefully you did the right tweaking, lol ?



#13 agmoonsolns

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Posted 22 September 2019 - 05:27 PM

The performance has been greatly improved. All I did was move a baffle and collimate the scope. 



#14 LDW47

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Posted 22 September 2019 - 05:42 PM

The performance has been greatly improved. All I did was move a baffle and collimate the scope. 

We’ll soon find out, lol !



#15 Jon Isaacs

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Posted 23 September 2019 - 06:43 AM

All you have to do is change the baffles to get the full 62mm of aperture. By doing that and making sure the lens is properly collimated, you end up with a really super little scope. These scopes perform MUCH better when you do that. I tweaked and adjusted mine to perfection.

In my case, it wasn't the baffle. When measure a scope at less that full aperture, I temporarily remove the baffle. 

 

I use an expanded beam laser with a 4.8 mm Nagler to measure the aperture.  The scope is first focused at infinity with the diagonal in place. I then fit the laser assembly over the eyepiece and measure the diameter of the projected beam.

 

Eyepiece and laser on floor cropped.jpg

 

The focuser was aligned, I am not sure what else there is one can do with a cemented doublet??  

 

Jon


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#16 LDW47

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Posted 23 September 2019 - 07:03 AM

In my case, it wasn't the baffle. When measure a scope at less that full aperture, I temporarily remove the baffle. 

 

I use an expanded beam laser with a 4.8 mm Nagler to measure the aperture.  The scope is first focused at infinity with the diagonal in place. I then fit the laser assembly over the eyepiece and measure the diameter of the projected beam.

 

 

 

The focuser was aligned, I am not sure what else there is one can do with a cemented doublet??  

 

Jon

 

So the specs may not meet those assigned to that scope ?



#17 Jon Isaacs

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Posted 23 September 2019 - 07:33 AM

So the specs may not meet those assigned to that scope ?

 

That's pretty common with small, F/5 achromats.  With a 1.25 inch drawtube, you have 1.25 x 5 = 6.25 inches of drawtube and diagonal before the drawtube starts to pinch the light cone.  A typical 1.25 inch diagonal eats up about 3 inches of that, leaving 3.25 inches for the drawtube. That's pretty short.

 

The ST-80 gets around that by having a somewhat larger diameter drawtube but they cut it very close.

 

From a practical point of view, whether it's effective aperture is 56 mm or 62mm really doesn't matter, the views will be very, very similar.

 

Jon


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#18 Jaimo!

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Posted 23 September 2019 - 03:07 PM

I had both the Cometron CO-62 and the Tasco 9VR, both made by Vixen and both were disappointing...  Images were soft and lack of magnification, kind of gimmick-y, particularly with the finder scope.  I feel you can do just as well, if not a little better, with a nice set of binoculars.  I also own a WO66SD, which is a MUCH better execution of a small wide field scope, although not in the same price category.

 

penny.gif penny.gif ,

Jaimo!


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#19 LDW47

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Posted 23 September 2019 - 05:04 PM

I had both the Cometron CO-62 and the Tasco 9VR, both made by Vixen and both were disappointing...  Images were soft and lack of magnification, kind of gimmick-y, particularly with the finder scope.  I feel you can do just as well, if not a little better, with a nice set of binoculars.  I also own a WO66SD, which is a MUCH better execution of a small wide field scope, although not in the same price category.

 

penny.gif penny.gif ,

Jaimo!

I do have a pair of 15x70 binos as well as 2 pair of 10x50’s. I bought it as an ‘ I want it ‘ scope to go with my other 6, with the size you can’t expect anything more than low power views and I don’t use finders at any time so this should be right down my alley so to speak ! I am not expecting miracles but there have been a lot of good things said about them over many years. 


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#20 LDW47

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Posted 08 October 2019 - 04:52 PM

Just got the scope today, here it sits on my heavy duty photo tripod with a 32mm Celestron Omni and a set of Bob’s Knobs on the focuser. I will give it a try tonite !

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#21 LDW47

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Posted 08 October 2019 - 07:06 PM

I had both the Cometron CO-62 and the Tasco 9VR, both made by Vixen and both were disappointing...  Images were soft and lack of magnification, kind of gimmick-y, particularly with the finder scope.  I feel you can do just as well, if not a little better, with a nice set of binoculars.  I also own a WO66SD, which is a MUCH better execution of a small wide field scope, although not in the same price category.

 

penny.gif penny.gif ,

Jaimo!

I just had a quick look at the moon, incl. with my Meade 4000 zoom and there was nothing soft in the images I witnessed and very little color. Sharp lines and even yellows, as expected, even jupiter and its moons weren’t bad considering what I thought was moisture in the air. There was no evidence of softness that you mention so maybe it was just a bad nite or something else bad or the softness wasn’t in the scope at all ? As to lack of magnification you or anyone else, with any experience at all, that bought this scope should have know and taken into account there would be a lack of mag. Nothing gimmicky here at least not with this scope ! I intend to try it again a little later tonite. I think its going to be just plain fun, a challenge.   PS: it sure wasn’t hard to split the double in the handle of the B Dipper when I zoomed up the power ! Anyone that isn’t into perfectionism would love this scope. 


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#22 agmoonsolns

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Posted 08 October 2019 - 07:13 PM

I am into perfection and I love these scopes. For widest possible FOV in an inexpensive package, these are hard to beat.


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#23 LDW47

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Posted 08 October 2019 - 07:42 PM

I am into perfection and I love these scopes. For widest possible FOV in an inexpensive package, these are hard to beat.

I am to, especially before retirement in my career designing / managing highway transportation but I don’t let it get in the way in this great hobby ! Its not a requirement, a must and it is nice to get away from at times, at least for me. Not knocking it, just avoiding it, lol !


Edited by LDW47, 08 October 2019 - 07:44 PM.


#24 LDW47

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Posted 08 October 2019 - 08:41 PM

One more small item before closing, through a medium zoom power M31 looked pretty d**n good, even with the bright moon high in the sky.



#25 Jon Isaacs

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Posted 08 October 2019 - 11:18 PM

. There was no evidence of softness that you mention so maybe it was just a bad nite or something else bad or the softness wasn’t in the scope at all ? As to lack of magnification you or anyone else, with any experience at all, that bought this scope should have know and taken into account there would be a lack of mag.

 

 

The 24 mm-8mm zoom provides magnifications from 12.5x to 37.5x.  That's not a lot of magnification. A decent 60 mm F/5 ought to manage reasonable views at something like 80x. My Cometron 62 never achieved anything like that. It suffered from astigmatism and probably coma, not pretty. 

 

The Carton 70 mm F/4.5 is quite colorful but has a good lens that's sharp.

 

In an ST-80, the zoom would provide 16.7x to 50x and reasonable views to 100x. That's pretty typical of the ST-80's I've owned, my current 80 mm F/5 does better.

 

If my Cometron 62 had had optics comparable to an ST-80, I would have kept it. How does yours perform on Gamma Andromedae?

 

Jon




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