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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
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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

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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
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Reged: 11/08/07

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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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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
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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
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Reged: 12/18/06

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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
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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
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Reged: 11/08/07

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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
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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
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Reged: 01/15/08

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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
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Reged: 01/18/07

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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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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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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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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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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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Greg Boynton
member


Reged: 05/29/09

Re: old C8 vs new C8 new [Re: Erik Bakker]
      #5694393 - 02/22/13 10:27 AM

I agree, I'll take the better figure over better coatings any day.

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magnus
professor emeritus


Reged: 03/17/04

Loc: Visby, Sweden
Re: old C8 vs new C8 new [Re: Greg Boynton]
      #5695038 - 02/22/13 03:54 PM

Thanks Greg & Erik for your opinions. I fully agree with you. -Rather good optics & less excellent coatings than the opposite.
In my initial post, I wrote as far as I can evaluate from startesting & observing Jupiter (well also Mars & Saturn)I find the optics not perfect but good for a massproduced optics. Maybe not saying all that much!?But: Comparing my C8+f/6.3 f/r vs my OOUK 8"f/6 Newt. with zygodocument stating something like strehl 98% and 1/7 wave and 44mm secondary,Hi-Lux coatings the Newt. shows Jupiter as just a bit brighter & whiter, with low contrast details just a tiny bit easier to detect in excellent seeing. Also the "e" & "f" stars in the Trapezium are defenitely easier to detect in the Newt.(Hi-Lux?)In "normal" conditions any differences are hard to notice.
Still my C8 get most use as it is so ergonomic and short, except when I use my Gemini alt-az mount, than the 8" Newt is my obvious choice. In case anyone is intressted

/Magnus 57N.


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WillCarney
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Re: old C8 vs new C8 new [Re: magnus]
      #5695111 - 02/22/13 04:32 PM

Well I have a black C-8 from the early 80's. It's great and recently I had it back to back with the clubs C-11 HD. Well would you know it. My C-8 out performed the C-11 HD visually with the same eyepieces. I actually got dimmer and brighter stars with my C-8. Hard to believe but I repeated it on several occasions. William

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rflinn68
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Re: old C8 vs new C8 new [Re: WillCarney]
      #5695183 - 02/22/13 05:09 PM

I have a mid-90's black tube C8 and I wouldnt trade it for anything other than an EdgeHD (8" vs 8"). Mine compared better than a friends similar model C8 and every bit as good as a brand new dark orange tube 8SE. I might even sell my 10" Meade SCT someday soon and buy the EdgeHD and keep my black tube C8. I like it that much! But I like my Meade too! Maybe I'll keep them both and just buy the EdgeHD! Everbody needs two 8" SCT's and a 10" SCT. Right?

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magnus
professor emeritus


Reged: 03/17/04

Loc: Visby, Sweden
Re: old C8 vs new C8 new [Re: rflinn68]
      #5695275 - 02/22/13 05:50 PM

Congrats Will & Richard to excellent black C8:s. Seems like I should be careful not to be blinded by XLT coating ads and truly have a second thought before I rush and buy a brand new C8 XLT. Well even if I did my beutiful 1973 orange Pacific C8 with it`s original thrunk will never be up for sale.-Just as my beutiful second hand Intes MK66!
/Magnus 57N.
PS Will, what was wrong with the C11. Something must be wrong if 8" outperforms 11",even if I have no doubts your 8" is very good indeed!!

Edited by magnus (02/22/13 05:57 PM)


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watcher
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Re: old C8 vs new C8 new [Re: magnus]
      #5695320 - 02/22/13 06:12 PM

I think, if this is going to be your only scope, you might consider an Edge 8 CPC. Passive cooling would be beneficial in your climate. The fork mounts are more comfortable to view with, and I haven't seen a single report of anything but great optical quality in any Edge scope. besides that, you will get the best coatings available. I just think if your only going to have one scope to do it all, it's worth spending a little extra.

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rflinn68
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Re: old C8 vs new C8 new [Re: watcher]
      #5695350 - 02/22/13 06:29 PM

Post Deleted by rflinn68

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Julio
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Re: old C8 vs new C8 new [Re: rflinn68]
      #5695451 - 02/22/13 07:31 PM

Optical figure trumps everything, some have tested their C8-C14s and have found that they surpass 1/8 PV. While not common, such a SCT of mass production is in the excellent to superb category and an outstanding value and worthy of reacoating.

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mike174
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Re: old C8 vs new C8 new [Re: Erik Bakker]
      #5695552 - 02/22/13 08:14 PM

Quote:

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.




I noticed that when viewing the moon through a Mewlon 250 a few towns away under typical NJ skies. The sharpness of the optics was easily seen through the seeing. My 2007/2008 C11 seems to loose sharpness when I go eyepieces smaller than 20mm.

My Orange C8 seems to be almost the same on either side of focus unlike my C11.

MIke


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Bill Barlow
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Re: old C8 vs new C8 new [Re: WillCarney]
      #5695564 - 02/22/13 08:22 PM

Seems hard to believe that your C8 can show dimmer and brighter stars than a C11. Did you do the side by side using similar magnifications or the same focal length eyepiece in each? This would make the C11 use a higher magnification given it's longer focal length. The much higher light grasp of the C11 should be noticeable versus the C8 I would think.

Bill


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Brian Risley
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Re: old C8 vs new C8 new [Re: rflinn68]
      #5695841 - 02/22/13 11:06 PM

Just 2 C-8's? I have 3 and also the club's CPC-800 along with my Meade 10!
Brian

Quote:

I have a mid-90's black tube C8 and I wouldnt trade it for anything other than an EdgeHD (8" vs 8"). Mine compared better than a friends similar model C8 and every bit as good as a brand new dark orange tube 8SE. I might even sell my 10" Meade SCT someday soon and buy the EdgeHD and keep my black tube C8. I like it that much! But I like my Meade too! Maybe I'll keep them both and just buy the EdgeHD! Everbody needs two 8" SCT's and a 10" SCT. Right?




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rflinn68
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Re: old C8 vs new C8 new [Re: Brian Risley]
      #5695910 - 02/23/13 12:06 AM

Quote:

Just 2 C-8's? I have 3 and also the club's CPC-800 along with my Meade 10!
Brian

Quote:

I have a mid-90's black tube C8 and I wouldnt trade it for anything other than an EdgeHD (8" vs 8"). Mine compared better than a friends similar model C8 and every bit as good as a brand new dark orange tube 8SE. I might even sell my 10" Meade SCT someday soon and buy the EdgeHD and keep my black tube C8. I like it that much! But I like my Meade too! Maybe I'll keep them both and just buy the EdgeHD! Everbody needs two 8" SCT's and a 10" SCT. Right?







The more the merrier, right?


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jrbarnett
Eyepiece Hooligan
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Reged: 02/28/06

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Re: old C8 vs new C8 new [Re: Julio]
      #5697493 - 02/23/13 10:38 PM

Better still, you can get used, recent C8s for $350. They depreciate a lot.

- Jim


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greedyshark
professor emeritus
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Reged: 10/31/05

Loc: 3rd Rock
Re: old C8 vs new C8 new [Re: bob midiri]
      #5698880 - 02/24/13 08:26 PM

Quote:

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...Bob




I agree with Bob 100%. I own an early '80s orange tube...outstanding optics! I will pass this one to my boy.

Charles


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rfic1
sage
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Reged: 10/25/05

Re: old C8 vs new C8 new [Re: greedyshark]
      #5698894 - 02/24/13 08:41 PM

I owned a 1976 Celestron Pacific C8 that I felt had outstanding optics. It almost always provided better planetary views than multiple 5" APO's I owned. I purchased a TEC 200MC and that is the reason why I parted with it. Yes the TEC is better, but at 7 times the cost. Plus it is not as portable and requires a substantial mount. I still miss that scope. One that I wish I never let go.

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Greg Boynton
member


Reged: 05/29/09

Re: old C8 vs new C8 new [Re: rfic1]
      #5700407 - 02/25/13 06:57 PM

I also had an orange 70's C8 that had really sharp views. I didn't appreciate how good it was though and sold it in a fit of aperture fever. After looking through a whole bunch of SCT's since and getting educated, I realized that I screwed up. I do agree that the newer scopes seem to be more consistently good, but I wouldn't count on any given sample as being an upgrade.

I guess the lesson is: Never sell a scope which gives great views unless you are dang sure the replacement is actually better for you.


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orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: old C8 vs new C8 new [Re: Greg Boynton]
      #5700467 - 02/25/13 07:41 PM

I have a C8 that was made for former Celestron VP of sales Leo Henzl, there are hand written notes on the back of the mirror in blue marker and it describes the extra figuring process and his name.
With my F 6.3 FF/FR I cant imagine anything sharper! I have owned C8's since the 70's this one is sure a keeper,
Even at the price I got it for.
I am debating sending the mirrors in for enhanced coatings.
The stock ones look good with no pin holes..
I just don't know what to do...


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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: orion61]
      #5700487 - 02/25/13 07:59 PM

Larry why mess with perfection!!! Enjoy that scope, how much can really be gained by the coatings. use a 99% reflective diagonal to increase a little light going to your eyepiece...if you don't already!! 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]
      #5704341 - 02/27/13 09:46 PM

This evening, before moonrise,I used my friend`s C8 XLT to see how it performes vs my old orange C8 Pacific -73. My friend Roger (sunrutas) is also a CN member but he is 100% imaginer, mostly planets. Now and than he visits solar system imagening forum to show his amazing Jupiter/Saturn pictures taken with his C8XLT & C925XLT.

Anyway this evening I got the chance to have a look tru`his C8XLT from his balcony, were he has a very solid pier & an CG-5 mount on top of it. I also often observe from my balcony so the conditions were very similar. I had taken my eypieces, diagonal & focalreducer with me to use on Rogers scope.

I had a look at Jupiter, Rigel, Alnitak, Trapezium, Sigma Orionis, gamma Leo. All in all I could not notice any distinct difference. Jupiter looked pretty much the same as in my old C8; details and contrast very much the same. Possibly J. was a bit whiter & brighter in XLT but I am not certain. No e or f star in Trapizium but not often I see those in my C8 either. (M42 don`t get high over horizion up here)More easy in my 8" f/6 OOUK Newt. But the four "original" Trap. stars were defenitely more distinct & pinpont in my C8. Strange! The C component in Sigma Ori. was harder to see in the C8XLT than in my C8.Even more strange!! I could not notice any difference when observing Rigel, Alnitak & gamma Leo.

A quick startest gave pretty much the same result in both scopes; not perfect but pretty good.

I am very surprised & glad how extremely well my classic C8 hold up against a brand new XLT. Tom Johnsson had certainly done his homework before starting massproducing the C8 1970!

A test C8 vs C8 XLT on a dark place with no moon might have tipped the advantage over to the C8XLT but I very much doubt it, not in a
dramatical way, anyway.

I will keep my beutiful 40 (!!) year old orange C8 Pacific & take good care of it & use it as much as I can.

Best Regards,
Magnus 57N.

PS Seeing was: ca. 5/10 P.


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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]
      #5704380 - 02/27/13 10:09 PM

Nice report Magnus, Im glad you saw for yourself... 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]
      #5704516 - 02/27/13 11:30 PM

Bob!

Thanks for advicing me to compare a new C8XLT vs my old C8; luckily I have a local friend with the C8XLT to compare with!

Back home this late night I had marvelous observation of Saturn at 240X, despite it was just 17 degrees above horizon and gamma Virgo was wide open at 411X.
Seeing had improved!

Now it`s time for bed!

/Magnus 57N.

Edited by magnus (02/27/13 11:38 PM)


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Eddgie
Postmaster
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Reged: 02/01/06

Re: old C8 vs new C8 new [Re: Greg Boynton]
      #5705159 - 02/28/13 11:37 AM

While I agree on this point, I am unsure that you have to make this an "Either/Or" proposition.

The C8s seem to me to enjoy the best consistency in terms of high quality optics of all the Celstron SCTs I have ever owned.

There may have been some Comet lemons out there, but I have never star tested a Celestron C8 that did not show very good to excellent optics.

I also agree that it would be very hard to see the difference between a older SCT or a Starbright SCT, or comparing a Starbright SCT to an XLT SCT, but in each case, the steps are minor.

The XLT also introduced the use of water white glass, so this is not at all a coating change.

The step in transmission between a pre-starbright and XLT SCT is on the order of 12% or so.

People on the eyepiece forum routinely report seeing transmission differences half of that.

Ah, but you would have to look for it.... This amount of transmission difference will only be readily apparent when doing limiting magnitude tests.

I also think a serious planetary observer that routinely uses very small exit pupils (.8mm or smaller) would indeed notice the light falloff because the image would dim sooner in the old scope.

So, for the most demanding usage, I think it is very likely that the difference would be detectable for anyone that was demanding enough to see it.
But for casual use, it could be ignored.


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bob midiri
Carpal Tunnel
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Reged: 06/17/04

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Re: old C8 vs new C8 new [Re: Eddgie]
      #5705538 - 02/28/13 03:18 PM

To me the money he saved by keeping the old C8 with great optics, compared to the minimal gain he might have achieved purchasing the C8XLT, he now is in position to purchase some excellent eyepieces and even a Di-electric diagonal to further increase his enjoyment of that wonderful classic scope. I own a Super C8 orange and a classic Orange C14, and I would NOT trade them in. I enjoy them too much....bob

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rflinn68
Carpal Tunnel


Reged: 03/09/12

Loc: Arkansas
Re: old C8 vs new C8 new [Re: bob midiri]
      #5707605 - 03/01/13 06:24 PM

I've heard that the reflectivity will decrease 1% per year. My near 20 year old C8 compared well to a brand new 8SE of a friends but I did think the image in his was a little brighter. Not sure if it was 20% brighter though

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vct123
sage
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Reged: 11/17/09

Loc: Staten Island, N.Y.
Re: old C8 vs new C8 new [Re: rflinn68]
      #5709258 - 03/02/13 06:04 PM

I just picked up a black tube Starbright c8, I actually traded my buddy for my 8"dob.
This is a good one with excellent optics and very little image shift.
To me the difference from the starbright to the xlt coatings
is minimal at best on most objects.
I have had many c8's and I just think its a great scope to have at hand.


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magnus
professor emeritus


Reged: 03/17/04

Loc: Visby, Sweden
Re: old C8 vs new C8 new [Re: bob midiri]
      #5711276 - 03/03/13 07:19 PM

Bob!

A TV 24 Panoptic will be nice to have + a binowiever with matching eypieces

/Magnus 57N.

Edited by magnus (03/05/13 08:23 PM)


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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]
      #5711279 - 03/03/13 07:23 PM

I hear you Magnus!! BTW post some pictures of that Classic C8 , I know I for one would love to see your scope. Clear skies. 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]
      #5711321 - 03/03/13 07:46 PM

Bob!
I will see if my astrofriend Roger can help me with that. Promise!
/Magnus 57N.


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orion61

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Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: old C8 vs new C8 new [Re: rflinn68]
      #5711666 - 03/03/13 10:39 PM

I thought that was for an open tube?
I have a 70's C8 that used to belong to Leo Henzl Jr.
Some of the pics in the old Celestron Sales catalogs were
taken through it!
Nice deal tho.
There is a Coulter 8 Dob on Shop Goodwill.com with a &5.00 bid on it right now...


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magnus
professor emeritus


Reged: 03/17/04

Loc: Visby, Sweden
Re: old C8 vs new C8 new [Re: rflinn68]
      #5711963 - 03/04/13 05:55 AM

Mine has lost 40% reflectivity if 1% loss a year is correct for a closed SCT
/Magnus 57N.


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RichD
Carpal Tunnel


Reged: 11/08/07

Loc: Derbyshire, UK
Re: old C8 vs new C8 new [Re: magnus]
      #5712216 - 03/04/13 10:19 AM

I'd be surprised if it was as much as 1% per year.

There are alot of classic C8s out there that are 30 years old and they still give great views, which couldn't be the case if they had dimmed by a third.


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vct123
sage
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Reged: 11/17/09

Loc: Staten Island, N.Y.
Re: old C8 vs new C8 new [Re: RichD]
      #5714602 - 03/05/13 02:33 PM

Guys don't get crazy, read the post, it says," I've heard the reflectivity will decrease 1% per year."
key word there, "I've heard".
Not saying the poster didn't hear it, but doesn't mean its true and makes know sense when you think about it.


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magnus
professor emeritus


Reged: 03/17/04

Loc: Visby, Sweden
Re: old C8 vs new C8 new [Re: vct123]
      #5715276 - 03/05/13 08:19 PM

I am perfectly calm; I do know it can`t be correct Maybe for an open Newt. it could be correct, but even in that case I doubt it. Could be correct if you do not take proper care of your Newt. primary. Maybe!

Magnus 57N.


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