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Equipment Discussions >> Cats & Casses

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magnus
professor emeritus


Reged: 03/17/04

Loc: Visby, Sweden
old C8 vs new C8
      #5688352 - 02/19/13 05:59 AM

Two years ago I bought a classic orange C8 Pacific 1973. It is in very good condition; nice, clean and no scratches what so ever. I have deforked it, mounted a vixen style rail on instead and use it on my CG-5 or Gemini alt-az. Also I have installed Bobs knobs and they work just fine if I have to collimate.
Short story long: I have had/have alot of fun with this scope. I have been observing since mid 60`s but this is my first SCT. I have been sceptic to SCT:s due to their large CO. Mainly I have used Newts.and still do.
But I have, since two years, started a loveaffair with this 8" SCT. Iam amazed how handy and portable this 8" scope is. The eypiece is always easy to reach (which is not the case in a Newt!)and it does not need a monster mount. I find my CG-5 just perfect and on my Gemini I would call it an 8" g&g!
As far as I can evaluate from startest and by observing Jupiter the optics on this old C8 is not perfect but as close to as one can expect in massproduced scopes.

As pleased as I am with this old C8 I am very curius if a brand new 8" with the famous XLT coatings will make differences worth buying a brand new one.
I am a visual observer and my focalreducer f/6.3 is permanently on my C8 in front of a 1.25" diagonal.

So my question to you my friends: Will it be worth the upgrade to a brand new XLT 8"? Itīs all up to me to decide, I know, but some advices here wouldn`t hurt.

Regards,
Magnus 57N.

PS My C8 has no coatings as far as I understand. Please correct me if I am wrong!


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jjack's
super member


Reged: 04/01/12

Loc: normandy
Re: old C8 vs new C8 new [Re: magnus]
      #5688364 - 02/19/13 06:21 AM

Hi Magnus !
During star parties i have tried a lot of theses SC8, without coatings, MGF2 coatings, starbright coatings and recently XLT coatings and i can tell you that the more recent coatings they have, the better is the contrast. And, for me, i see a huge difference !
The coatings on the corrector and mirrors are not the only responsible. The glass of the correctors is now made with BK7, a more translucent glass than old "green" plate glass.

Edited by jjack's (02/19/13 06:26 AM)


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azure1961p
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Reged: 01/17/09

Loc: USA
Re: old C8 vs new C8 new [Re: jjack's]
      #5688413 - 02/19/13 07:45 AM

Focus shift - at lest in my c6 is non existent.

Pete


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RichD
Carpal Tunnel


Reged: 11/08/07

Loc: Derbyshire, UK
Re: old C8 vs new C8 new [Re: azure1961p]
      #5688418 - 02/19/13 07:50 AM

I think you almost certainly would notice a difference - in contrast as said above but maybe also in brightness too.

Modern multi coatings are wonderful things and can make a scope or binocular of certain aperture behave like a larger aperture compared to many years ago. I'd say go for it - the C8 is a great scope and if you know you enjoy that size SCT then it will be a winner for you.


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Eddgie
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Reged: 02/01/06

Re: old C8 vs new C8 new [Re: magnus]
      #5688539 - 02/19/13 09:27 AM

The basic SCT design has not changed, but the coatings and materials have.

The transmission (and contrast improvment from coating the rear of the corrector) has indeed improved, and the latests scopes have a different glass for the corrector (water white) that improves performance by itself almost as much as the coatings on the front.

Still, the total improvment is likely only about 20%. This is not going to may you gasp. Brigther? Yes.

One of the major improvements though was not for light transmission. Initially, the rear if the correctors was not coated. This meant that bright off axis light could reflect off of the primary mirror and then rather than passing back out through the rear of the corrector, could then reflect back down into the baffle, lowering contrast. For bright targets like planets and especially the moon, this could do a lot to lower contrast.

Still, the difference between an old scope and the newer ones will not be glaring. Subtle but not "Wow" by any means.

Is it worth upgrading though? I would say yes. If you love the size, weight, capability and ergonomics of the C8 (and these are what make the C8 perhaps the best selling telescope of all time) then why not get a newer one?

Used C8s are perhaps the very best value in all of astronomy. I have paid far more for a lot of smaller reflectors and refractors that did not give me nearly the enjoyment of my C8s.

And if you really want to splurge for a "Lifetime" C8, get an EdgeHD 8".

A lot of telescopes have come and gone for me over the decades, but it seems like there is always a C8 in my life, and since getting the EdgeHD 8", I would say that it will be the scope that will stay with me until the end. I use it more than I use my 6" APO. It is that good.

So don't expect a big difference in performnce. Rather subtle in fact if your current scope has very good optics. But every improvment in performance adds up, and if you love the C8, why not have a better C8?


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magnus
professor emeritus


Reged: 03/17/04

Loc: Visby, Sweden
Re: old C8 vs new C8 new [Re: Eddgie]
      #5690167 - 02/20/13 03:52 AM

Thank you all for kind & informative feedback. What a great place CN is for help & advice!!
I have been certain to get a 100-120mm ED refractor but maybe a brand new C8 will suit me better as I have found the 8" SCT concept outstanding.(fracfreaks may think otherwise!!) I really do love the size, weight, capability and ergonomics so much!
The 8"EdgeHD is also tempting but it`s more expensive and for visual observing I need expensive wide field eypieces to fully enjoy the comafree field. Right? Beside there is no focalreducer for this SCT to shorten the f/10 ratio which is a bit too much"tunnelvision" for my taste.

/Magnus 57N.


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bob midiri
Carpal Tunnel
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Reged: 06/17/04

Loc: pa 19320
Re: old C8 vs new C8 new [Re: magnus]
      #5690180 - 02/20/13 04:19 AM

I recommend that you find some one local that has the Newer C8 that you are thinking of purchasing and see for yourself how your old C8 compares in a one to one showdown, directly with that scope using the same eyepiece and same diagonal. It might not be as big a jump as you might be anticipating. Unless you are a very discriminating observer you might be a tad dissapointed in the gain you think you are making. Many years of observing with my eyes!! Good luck to you. Bob

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magnus
professor emeritus


Reged: 03/17/04

Loc: Visby, Sweden
Re: old C8 vs new C8 new [Re: bob midiri]
      #5690196 - 02/20/13 05:07 AM

Thanks Bob! I have local who has an XLT C8. If I can just make him stop for a while imagening I hope to borrow his scope for a couple of hours to evaluate:-)Unfortuneately I am a rather discriminating observer!
/Magnus 57N.


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Illinois
Carpal Tunnel


Reged: 12/18/06

Loc: near Dixon, Illinois USA
Re: old C8 vs new C8 new [Re: magnus]
      #5690354 - 02/20/13 08:24 AM

If need new one then why not C9.25 and keep good old classic C8!

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bob midiri
Carpal Tunnel
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Reged: 06/17/04

Loc: pa 19320
Re: old C8 vs new C8 new [Re: magnus]
      #5690422 - 02/20/13 09:12 AM

Quote:

Thanks Bob! I have local who has an XLT C8. If I can just make him stop for a while imagening I hope to borrow his scope for a couple of hours to evaluate:-)Unfortuneately I am a rather discriminating observer!
/Magnus 57N.




Well Magnus then with your discriminating eye, a direct comparison will tell you all you will need to know. I have a terrific Classic C8, with superb SCT optics, and in my mind I would have to be blown away with another 8" SCT to make a change, BUT the laws of physics just wont allow that to happen for me. In order to do that I would need more aperture and similar quality figured optics. Good luck and we all will be interested in your findings. Bob


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RichD
Carpal Tunnel


Reged: 11/08/07

Loc: Derbyshire, UK
Re: old C8 vs new C8 new [Re: bob midiri]
      #5690530 - 02/20/13 10:03 AM

I think the OP should go for an 8" Edge HD. That is a real step up from a classic C8 in every way - build quality, contrast, on axis and - very noticeably - off axis sharpness. I can't believe how good the Edge series is, it was a real eye opener for me.

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Eddgie
Postmaster
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Reged: 02/01/06

Re: old C8 vs new C8 new [Re: magnus]
      #5690535 - 02/20/13 10:05 AM

Quote:

I need expensive wide field eypieces to fully enjoy the comafree field.




To some degree, you are indeed correct. For visual use, the EdgeHD is at its best with 82 degree AFOV eyepeice (or even 100 degree AFOV types).

But consider this carefully.... If you buy an EdgeHD 8", you can start with less expensive types and as they years go by, you can add some 82 degree types.

But you can never "Add" EdgeHD performane to a standard SCT.

And trust me on this, but there are very few objects that won't fit into the field of an EdgeHD 8" with a 31mm Nagler or 41mm Panoptic.

Heck, the vast majority of targets fit into the field of a C14. There is not a lot of benefit in using a focal reducer for visual use. You get a bit wider field, but the edge of the field is illuminated to far less than it would be using just a 2" diagonal and a 41mm Panoptic or 31mm Nagler (and there are other choices too so don't think that I am saying you need these exact models).

As I said in my earlier post, I beleive that eveyone should have a C8 (and better yet, an EdgeHD) because of all of the virtues that you yourseld find attractive.

The EdgeHD design represents the literal pinacle of perfection for SCT design. There are no further meaningful improvements to be had from the design, so you have no fear of obolesence.

To me, the EdgeHD provides views that are even better than my 6" APO. Just as sharp right to the edge when using modern widefields, and a bit brighter view to boot.

Not everything fits into the field, by most stuff does, and the stuff that doesn't fit can always be viewing in an 80mm refractor. That is fine for targets like M22 an M45 where the primary need is a wide true field.

Just my own opinion, but the EdgeHD 8" is a no brainer vs the stanard 8".

When it comes to the larger scopes (C11 or C14) vs their EdgeHD stablemates, it is not as clear a value proposition to me because of the cost and the less desirable bloating that comes from 82 and 100 degree AFOV eyepeices. I prefer using Panoptis in my C14 vs Naglers not only because they suppress the coma and field curvature, but in larger scopes, even seeing will bloat the stars at the center of the field. For a given true field, stars usually appear more pinpoint even at the center when using Panoptics vs Naglers in these big scopes.

But for the EdgeHD, the price difference is not nearly as extreme, and the long term benefits of the design allow you to aquire a few high quality wide field eyepcies over the years. You don't need them all at once and you can add them as you go along.

But you can't turn the scope into an HD if it doesn't start as an HD.

Get the EdgeHD 8". You will never have a regret, I promise you.


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teskridg
Pooh-Bah


Reged: 01/15/08

Loc: PA
Re: old C8 vs new C8 new [Re: Eddgie]
      #5690616 - 02/20/13 10:47 AM

I upgraded from a CPC-800 to a CPC-1100 because with a binovieweer, which I use exclusively, globular clusters look more resolved than with the C8. I got mine for roughly the price of an Edge HD 8. Tim

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Julio
sage
*****

Reged: 01/18/07

Loc: Pembroke Pines ,FL
Re: old C8 vs new C8 new [Re: teskridg]
      #5690741 - 02/20/13 12:07 PM

I believe the Edge HD scopes are fantastic, however one can find a C8 OTA Orange tube for $799 and the edge starts at $1300 thats a $500 dollar difference. Assuming equal optical performances the difference is noticeable only at the edge.

Edited by Julio (02/20/13 12:09 PM)


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Eddgie
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Reged: 02/01/06

Re: old C8 vs new C8 new [Re: teskridg]
      #5690956 - 02/20/13 01:49 PM

Yes, and if you had asked me for my advice in choosing between an EdgeHD 8" or a standard C11, I would have suggested the C11.

But the OP has expressed his desire to stay with a C8 size package, and his choices are either a standard C8 or the more expensive EdgeHD 8".

I would not stop the eyepieces I own today or could own in the future influence my decision on going to the EdgeHD.

I would get the EdgeHD today and upgrade eyepieces over time as budget allowed, even if I had to use some Plossls in the short run.

90% of the performance difference in telescope design performance is in how a telescope performs once you get away from the center of the field.

Off axis, my EdgeHD 8" has performance that is every bit as good as my 6" APO. No other reflecting telescope I have ever owned came close to this level of off axis performance.

I think this is what gives a lot of the refractor zealots their bragging rights. And they are right... Compared to most reflectors, most refractors are very poor off axis performers.

But the EdgeHD is every bit as good. Maybe better because the field is so amazingly flat.

If I had a C8 want wanted to upgrade to a better C8, I would get an EdgeHD 8"

Oh, silly me... I did get rid of my super-excellent C8 (Gwen, read my review on Gwen) and replace it with an EdgeHD 8".

And it was the best "New" telescope purchase I have ever made.


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magnus
professor emeritus


Reged: 03/17/04

Loc: Visby, Sweden
Re: old C8 vs new C8 new [Re: Julio]
      #5690983 - 02/20/13 02:10 PM

Thanks again for many thoughtfull advices here; I am truly considering them all.
By the way, Illinois, I am sure C9.25 is a real fine scope but it comes with twice the weight vs 8" but just 1.25" aperture gain. Don`t think my CG-5 will handle it as rock steady as my C8.
Eddgie, the f/6.3 f/r is important to me, maybe it`s just in my imagination but it`s important!?
8" is 8" and if the optics are good I am perhaps just splitting hair by hunting good coatings?!
Lot to think of, but trying out a new C8 myself will be prio one of course.

/Magnus 57N.

Edited by magnus (02/20/13 02:26 PM)


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Eddgie
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Reged: 02/01/06

Re: old C8 vs new C8 new [Re: magnus]
      #5691240 - 02/20/13 04:11 PM

Well, as I said in my first post, the new coatings and water white glass of the XLT coatings do make for a very slight increase in brightness, but subtle.

This is why I don't know if the move from the standard model to a later XLT would be very meaningful especially if you think your optics are otherwise very good.

Will you see a slight difference? Maybe... Compelling enough to make it worth the change to an XLT? For me personally, the answer would be no, not to me personally.

My last C8 had non-Starbright (non-XLT coatings) and to be honest, the step to the XLT coatings of the EdgeHD was not enough to be easily noticeable. Only a very subtle increase in brightness.

But the difference in off axis performance was quite apparent (to me, though many don't seem to think so).

Here is the really great news though. Used XLT C8s are very inexpensive and they are just about fully depreciated. Get one and see if the difference is worth it, and if not, just turn around and re-sell it.

I have done that with a dozen scopes (buy then to try them and re-sell if I don't like). At the worst case, I was usually just out of shipping costs.

So, a very low risk to find out if the coatings make much of a difference.


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magnus
professor emeritus


Reged: 03/17/04

Loc: Visby, Sweden
Re: old C8 vs new C8 new [Re: Eddgie]
      #5692999 - 02/21/13 03:56 PM

Teskridg:Congrats to the CPC-1100 what must be a great scope. I have been considering that scope but it`s just too cumbersome for me to carry up and down the staircase to & from my flat and packing it into the car for travel to dark skies. Though it shows far more than 8" I think I won`t use it as often as the 8" size.I just love the 8" SCT format, giving it`s compactness and still decent aperture.
A complete CPC-1100 is roughly twice as expensive as a new 8" Edge OTA here in Sweden.

Eddgie: I wish things were as easy as you describe when it comes to buying & selling secondhand scopes here in Sweden as it seems to be in US. After all we are only 9 million people here and the market is very limited. Not often you see a serious scope for sale here in classified ads.So I felt lucky when I could grab my "dreamcope" since early -70, the orange C8 in very good condition And selling a serious scope is not easy either even if you degrade youself by setting the price very low.
When I look at class.ads. here on CN or AM I think I am on another planet; so much to choose from and so very low prices.
Lucky you!!!

Anyway I e-mailed my local Swedish Teleskop-Service resaler for more info on the 8" Edge today. Price is 13950 Skr = $ 2150 if I have the currency correctly in my head. A brand new 8"XLT standard is 9800Skr


/Magnus 57N.


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moynihan
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Reged: 07/22/03

Loc: Lake Michigan Watershed
Re: old C8 vs new C8 new [Re: Eddgie]
      #5694146 - 02/22/13 08:03 AM

Quote:

Quote:

I need expensive wide field eypieces to fully enjoy the comafree field.




To some degree, you are indeed correct. For visual use, the EdgeHD is at its best with 82 degree AFOV eyepeice (or even 100 degree AFOV types).




Interesting. Given the apparently improved field flatness/correction, i had assumed that simpler eyepiece designs would be at their best, also given the long FL, compared at least to must dobs.
Or is your answer in reference to achieving the wide field experience?


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Erik Bakker
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Reged: 08/10/06

Loc: The Netherlands, Europe
Re: old C8 vs new C8 new [Re: magnus]
      #5694173 - 02/22/13 08:26 AM

Magnus,

If your C8 has very good optics, that quality will have a profound impact on high power detail and contrast. No modern coating can make up for that. Only if the modern sample has similar high quality optics, than the coatings will add a little extra. Make sure you test any new C8 side-side with your old C8 at identical magnifications with identical eyepieces and diagonals. The coatings will do good on very low power views. As soon as you go to 150x and up, the quality of the optics will reveal themselves. Not only in the level of detail, but also in the steadiness of observable detail. Like the better scope has better seeing, while in fact it has better optics under similar seeing.


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