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Vintage black tube C-90 vs the newer ones

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#1 grif 678

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Posted 11 September 2020 - 08:06 PM

I have a very nice vintage C-90, the black tube one, with the better coatings. It has .965 accessories, which is not a problem with me. The newer ones have 1.25 accessories. The new ones are cheap, you can get one for around $150 with a backpack. Some differences also would be the focusing mechanism, with the vintage one being focused by turning the front part of the OTA, while the newer ones use the more common focus knob at the back.

The vintage ones sold around $450 to $500, depending where you got them at. So I would say that the newer ones are quite a good buy, because I have heard that the optics are pretty darn good. I would think that the 45 degree diagonal would be one drawback.

I really like my old one, have thought maybe about getting a newer one since they are so cheap, but the views would have to be a lot better for me to do that. Mine was made in Japan, and I purchased some nice Japan made .965 eyepieces for it.

Just for common knowledge, if anyone has used both of these, is there really that much difference in the views. Remember, I have no problem with the .965 eyepieces, since they are all quality Japan made. And with my 90 ETX, I have two nice examples of a 90 mak, I just like this size scope for ease of use, especially since I have passed the big 70 year mark.


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#2 Terra Nova

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Posted 12 September 2020 - 07:58 AM

Have you read this thread? At 104 pages now it shows that there are a lot of very happy campers enjoying the new one. Ed Ting also reviewed it very favorably a couple of years ago. I’ve not looked through one but I did have an orange C90 with the plumbing thread helical focuser. I’ll just say that I was less than enamored with it.

 

https://www.cloudyni...g#entry10477924


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#3 PXR-5

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Posted 14 September 2020 - 10:49 PM

The new C90 is a great scope, a lot of fun for so little :)

It's like the ST-80 of CATs :)
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#4 GreyDay

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Posted 15 September 2020 - 05:29 AM

 I did have an orange C90 with the plumbing thread helical focuser. I’ll just say that I was less than enamored with it.

I've looked through an vintage black tube C90 and a SW90mak side by side, the SW90 had a noticably "cleaner" image and was easier to use.

 

Considering the vintage C90's go for around the same money as the new C90, i guess some people would have difficulty choosing between "classic status", and performance, but if the SW90 is anything to go by I'd buy the new C90 over the vintage..

 

To make a point... the following week i bought a SW102 dispite the vintage black tube C90 being for sale for less money. Sure the vintage C90 is a "classic" and it does what it does well "for its time and its design", if it had performed as well as the skywatcher i'd still have thought twice as the SW90 has none of the issues regarding collimation, focusing, accessories etc.

 

I think half the reason i prefered the new over old was that the vintage C90 didnt quite live up to my expectations, or what i'd read in the "Orange tube C90" thread here on CN. Admitedly i'm comparing from a single sample but it was a very well looked after and well collimated example.


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#5 Terra Nova

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Posted 15 September 2020 - 08:04 AM

I've looked through an vintage black tube C90 and a SW90mak side by side, the SW90 had a noticably "cleaner" image and was easier to use.

 

Considering the vintage C90's go for around the same money as the new C90, i guess some people would have difficulty choosing between "classic status", and performance, but if the SW90 is anything to go by I'd buy the new C90 over the vintage..

 

To make a point... the following week i bought a SW102 dispite the vintage black tube C90 being for sale for less money. Sure the vintage C90 is a "classic" and it does what it does well "for its time and its design", if it had performed as well as the skywatcher i'd still have thought twice as the SW90 has none of the issues regarding collimation, focusing, accessories etc.

 

I think half the reason i prefered the new over old was that the vintage C90 didnt quite live up to my expectations, or what i'd read in the "Orange tube C90" thread here on CN. Admitedly i'm comparing from a single sample but it was a very well looked after and well collimated example.

Your thoughts and experiences coincide exactly with mine. Everytime I had my old orange C90 out, I would think to myself why?! I could get sharper, crisper views and much more reliable performance with my 60mm refractors and set up and take down would be just as easy. Compared with a 3” and it was totally out classed; and once the Questar came, end of story.


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#6 GreyDay

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Posted 15 September 2020 - 02:49 PM

 Everytime I had my old orange C90 out, I would think to myself why?!

 

Compared with a 3” and it was totally out classed; and once the Questar came, end of story.

As you said earlier Terra, Ed Ting pretty much summed it up in his review, the new C90 is worth the money and performs well. Sometimes we have to accept that maybe Synta have got it right with their designs and modern coatings. The orange tubes were good for their time so i understand the appeal or nostalgic value but they are out classed by todays standards, my own experience did leave me with a feeling of "why?!".

 

My SW102 reminds me visually of my Towa339 80/f15 but in a smaller package which is why it's my holiday scope and occasional GnG. I doubt it would beat a Questar for outright detail but then the SW102 isn't a hand finished perfectly engineered heirloom class telescope, but Synta are getting better all the time.


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#7 RichA

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Posted 15 September 2020 - 11:10 PM

Have you read this thread? At 104 pages now it shows that there are a lot of very happy campers enjoying the new one. Ed Ting also reviewed it very favorably a couple of years ago. I’ve not looked through one but I did have an orange C90 with the plumbing thread helical focuser. I’ll just say that I was less than enamored with it.

 

https://www.cloudyni...g#entry10477924

I think it's good to remember that (I think) Celestron intended it to act as a long-focal length camera lens when it was introduced, hence the barrel focusing.  Back then, they didn't hate mirror lenses with a vengeance like photogs do today. 


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#8 bremms

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Posted 16 September 2020 - 12:56 PM

Had an Orange and a Black vintage C90.. Meh... Black one was passable at best. The orange maybe a hair better. Polaris C80 trounced them.


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#9 clamchip

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Posted 16 September 2020 - 06:59 PM

I've found the orange C90 can be excellent if collimation is spot on, I think the

mirrors are better than the Chinese mirrors. I don't like the barrel focuser for astronomy

but I love the barrel focuser for nature because its so fast.

I've owned a few of the Chinese Synta made Mak's, 90mm and 127mm. Synta makes

these for Orion, Celestron, Skywatcher, and probably others. They are very good and

I really love their simplicity, I've had to repair a few I bought in non-working condition.

Not to change the subject but the ETX90 is best of all !

Buy the UHTC (Ultra High Transmission coatings) ETX90.

Meade really knows how to make a MCT. I've own the 7 inch, 3 90mm, a 5 inch, and I

recently bought a ETX125PE model the latest and greatest.

I'm working on a Synta made Bushnell 90mm (same as the others like Celestron) its

the latest generation with the rear cell held to the tube with three screws rather than

threaded on. It was a Goodwill purchase and it got banged around pretty bad but I

think it will be OK. All of these really benefit from lining the tiny baffle tube with flock

paper.

Robert

 

post-50896-0-35357600-1550968589_thumb.jpg

post-50896-0-06424200-1550968603_thumb.jpg

post-50896-0-88541500-1550968618_thumb.jpg


Edited by clamchip, 16 September 2020 - 07:17 PM.

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#10 RichA

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Posted 16 September 2020 - 09:57 PM

I've got one of the Bushnell 4" units.  Got it from a camera store going out of business with the flimsy goto mount for $70.00.  It is not as good optically as the ETX's.  Like you found with the flocking,

 

Your thoughts and experiences coincide exactly with mine. Everytime I had my old orange C90 out, I would think to myself why?! I could get sharper, crisper views and much more reliable performance with my 60mm refractors and set up and take down would be just as easy. Compared with a 3” and it was totally out classed; and once the Questar came, end of story.

Celestron ran an ad decades ago that said they were as good as the Questars.  Their words were more on the line like: "Are competing brands better than the C90?  Absolutely No!"  At the time, Questar was the only 90mm competition.  The only real competition to the Questar (optically) has been  the ETX90.


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#11 wfj

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Posted 18 September 2020 - 06:17 PM

Went through 50+ vintage C90's since they came out. When star tested or DPAC'd, they'd generally have obvious optical flaws (SA due to poor/non-existent aspherization - necessary for  f <15 for Gregory "spot" Mak's, irregular/zones due to mirror/corrector fabrication flaws). With so many got used to seeing them as boat anchors others would fob off on me, and in many cases would reject them as part of a deal or freebies.

 

Picked up a nice tripod for $20 that came with a C90. Almost dropped it off unexamined with a friend's kid - who didn't want it. Spot of bad weather kept me inside with nothing to do, so I DPAC'd it (among others) and got a two bar straight pattern I wasn't expecting. (I've had other 90mm Mak's as well and while not "turkeys", they generally don't make it that far, usually 1/3-1/5 wave - American ETX and various brand Chinese made. Bad luck with a "cheap" Q too, although I've used better ones.)

 

It was still "muddy" on Jupiter, but star tested well. Noticed lots of "veiling glare", a sign on CATs of bad baffling. Still wanted to get rid of it because it's tedious to focus. But ... got it for cheap/nothing, perhaps Dr. Frankenstein could "experiment" on a not so dear scope? Noticed that the baffles seemed to be specularly "illuminated" on bright objects, so using the worst case of  detail in the center of the full moon, compared contrast with an excellently baffled 65mm f/15 refractor. Really bad vs really good.

 

On the advice of a member here, removed the stock baffles and designed a thin metal primary baffle, left the secondary off (spot is way oversized, only an inch is used of it). No flooding even on full moon case. Comparing again, found detail close to refractor, lost the "muddy". It was easier to focus because it was "snap to" - the contrast made the difference. Still a pain mechanically to focus - over/undershoot. Lapped threads to "smooth", used wife's thinnest viscosity hair oil to reduce drag - single finger focus made it tenable, doesn't shake.

 

Yes you can get a vintage orange tube C90 to do well. It's very handy to have one like this, because it's compact and performant. Performant. And I'd never think I'd ever say that about a C90.

 

It still isn't made well mechanically. No mirror cell. Tedious to collimate if at all possible. My changes work best with only the 1.25" visual back and a mirror diagonal (correction ideal). Difficult to remove 3-4mm annulus of center spot to "optimize" CO. Focuser is an unsubtle NC pipe thread few can master w/o "jiggle".


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#12 Bomber Bob

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Posted 18 September 2020 - 06:33 PM

I like my black-tube C90 spotter, and added a 5x24 finder to it:

 

C90 BT Spotter S17 (Finder Install).jpg

 

But... my 1990s Meade ETX-90RA was a better MCT; and, my 1958 Questar Standard is better than the ETX.

 

While I had my C90 apart (adding the finder bracket), I gave the interior a thorough cleaning & blackening.  Like my 1976 C5, my C90 is a Fun Scope, and there's nothing wrong with that.



#13 PETER DREW

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Posted 19 September 2020 - 05:42 PM

I made the first UK constructed commercially offered 90mm Maksutovs in the mid 1970's, optics by James Muirden and latterly by David Hinds.  They were F11 native focal length with primary mirror focusing similar to the Questar and were commonly known as the "poor man's" Questar.  They were nearer to Questar performance than the later C90 but the C90 eventually killed it due to lower price.  Must have made getting on for 100 units, some with fork equatorial mounts.  Moved up to 6", 8" and 12" versions but again struggled with lower priced competition from Celestron and Meade with their SCT's.


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#14 wfj

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Posted 20 September 2020 - 12:09 PM

I made the first UK constructed commercially offered 90mm Maksutovs in the mid 1970's, optics by James Muirden and latterly by David Hinds.  They were F11 native focal length with primary mirror focusing similar to the Questar and were commonly known as the "poor man's" Questar.  They were nearer to Questar performance than the later C90 but the C90 eventually killed it due to lower price.  Must have made getting on for 100 units, some with fork equatorial mounts.  Moved up to 6", 8" and 12" versions but again struggled with lower priced competition from Celestron and Meade with their SCT's.

I wouldn't have believed you until fairly recently that a Gregory "spot" Mak could do that well.




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