jonbosley
professor emeritus
Reged: 10/19/05
Posts: 694
Loc: Texas
|
|
I went to my first star-party last Saturday and had the chance to view though both a meade LX200GPS CAT and a Celestron C8 (older model).
I have been thinking of buying the 9.25C as my next scope but now have paused for thought. The view from both these scopes was good the older 8C had a little edge on the meade. The meades tracking and goto was fantasic better then mine (but makes a lot more noise). But I have to say that the view through my scope is better then both of them. Jupiter was much more sharpe and M13 jumps out more. I do have a good mirror 1/10th wave tested by woden. I also laser coll my scope everytime I use it.
I am not bias to Reflectors as I have been looking to get a CAT as an up-grade but now maybe I should look at a 10 or 12 inch Reflector as the road to go.
Jon
--------------------
Mobile
9.25 EdgeHD Celestron
Atlas Hyper-tuned Mount
Trenched
RCX400 12" Meade
POD Observatory
Reserves
WO 66 SD Doublet APO Refractor
AstroSystems Quantum 18" f5.5 Zambuto Optics
|
Bob W6PU
Carpal Tunnel
Reged: 12/23/04
Posts: 2278
Loc: Springer-N.E.NM
|
|
Jon, there's just nothing like personal observation to make up ones mind!
Sounds like you've a great mirror in your 8", and of course, collimating regularly is everything!
Cheers!
Bob in NM
10" F/5 Coast Inst. Treckerscope Newt.
|
Alan French
Night Owl
Reged: 01/28/05
Posts: 4009
Loc: Upstate NY
|
|
Pretty much my experience too, with both an 8" f/8 and an 8" f/9 Newt.
Clear skies, Alan
|
erik
telescope surgeon
Reged: 01/30/04
Posts: 24789
Loc: Hawaii
|
|
frankly, i'd be surprised if the results were any different. SCT's have more surfaces, a bigger central obstruction, and take longer to cool down than most newtonians of similar aperture. i am probably a bit biased in my taste towards reflectors, and i have seen some SCT's that gave excellent views. but in these types of side by side comparisons, i've usually had similar results, with the reflector showing the better overall image... 
--------------------
-Erik Wilcox
Starstuff
Homebuilt 16" Truss Dob in Ohia Forest Observatory
(12' X 12' rolloff under Mag 7 skies)
8" Antares f/5 Newt
SV 80mm ED Nighthawk NG on M1 ALT/AZ
Nikon Prostaff 65mm spotter on Trekpod
Konusvue 20x80 binos
Homebuilt 80mm f/5 refractor
Mirador 60mm f/12 1960's refractor
|
Patrick
Postmaster
Reged: 05/16/03
Posts: 10382
Loc: Franklin, Ohio
|
|
My experience is also that a Newtonian reflector will give better images than a same sized SCT. The difference between the two is how much room I'll have left in the car going home from an observing session.
Patrick
--------------------
CPC1100;AT66ED;Denk S1;
EdgeHD C8; C6 SCT
6"f/4.8MN ES Comet Hunter
10"f/6 Newt
Vixen GP2;CGEM Mount
Canon 60D;Lodestar Guider
The Lord sits enthroned above the circle of the earth...He stretched out the heavens like a canopy.
|
Foehammer
professor emeritus
Reged: 06/29/06
Posts: 546
Loc: Cyprus
|
|
I also had the same worry, whether or not a CAT and a newt of the same size will be identical in image brighness and quality. Sure the CAT will be more compact (half the size) than the newt, but the newt will be half the price (or less) and give better images. Good thing i went for the newt eh?
I wonder if its the same story in 12"+
Let it be known worldwide, Reflectors rule! :-)
--------------------
Regards,
Agapios Elia
www.agapioselia.com
C9,25& DBK21
|
Heath23
super member
Reged: 07/03/06
Posts: 160
Loc: Rochester, NY
|
|
Quote:
I went to my first star-party last Saturday and had the chance to view though both a meade LX200GPS CAT and a Celestron C8 (older model).
Jon! I actually hit my first star party this past Saturday! Let me tell you this... I shopped and shopped and did a lot of research to determine what type of scope I would buy...Well, going to this event confirmed my decision!! Not a single SCT there!! Every scope in sight was a Dob. Truthfully, I was bummed. I too wanted to compare the views... Dobs "as far as the eye could see!!!" (actually a bit farther than the eye could see... it was dark!) 
--------------------
Heath
Custom built 8" pole dob + Moonlite(CUSTOM)CR2
|
pollux
artiste
Reged: 04/01/04
Posts: 7307
Loc: Burnaby Canada
|
|
I too when I thought about getting the Celestron C9.25 or C8 as my "big" scope my friends discouraged me to do that.
I ended up having a 8" Antares Newtonian. Half the price of the C8. I haven't got a chance to do a direct comparsion with this scope and C9.25 or C8, but the things I see through the Antares Newtonian are excellent.
--------------------
My Web Site
|
reflector74
Pooh-Bah
Reged: 10/09/05
Posts: 1249
Loc: Milky Way Galaxy, Orion Arm
|
|
Quote:
Pretty much my experience too, with both an 8" f/8 and an 8" f/9 Newt.
Clear skies, Alan
I own an 8" f/9.2 Newt. It is a fine scope.
--------------------
Two eyes and a preference to use both
|
reflector74
Pooh-Bah
Reged: 10/09/05
Posts: 1249
Loc: Milky Way Galaxy, Orion Arm
|
|
Quote:
I too when I thought about getting the Celestron C9.25 or C8 as my "big" scope my friends discouraged me to do that.
I ended up having a 8" Antares Newtonian. Half the price of the C8. I haven't got a chance to do a direct comparsion with this scope and C9.25 or C8, but the things I see through the Antares Newtonian are excellent.
We probably from what I know share some common friends.
--------------------
Two eyes and a preference to use both
|
PeterDob
sage
Reged: 07/29/05
Posts: 428
Loc: Carů, Italy
|
|
Allright, let me be the one voice to fall out of tone here. I've owned a Nexstar8 and have made extensive comparisons with my friend's 10" Skywatcher Dob. Frankly, I could hardly see any difference! True, maybe the Newt had a tiny tad more contrast. But it had 2 extra inches as well. I've even put the Nexstar side by side to my former 14" Dob and I was actually surprised to see how the Nexstar held its own. It split the double-double just as easily as the Dob and it also provided beautiful DSO images. Of course, regarding DSO there is no comparison, but I guess that you have to be a VERY discerning observer to notice any difference between a good 8" SCT and a similar Newt. It would be interesting if one could do a blindfold test because I'm sure that many would mistake the SCT's view for the Newt's. Then again, there is indeed a price difference. But at hardly $800 for a fully equipped Nexstar, probably a lot less scond hand, the difference isn't all that big. And I was always laughing when it was time to break up and go home. I just lifted up the Nexstar, put it with its tripod under the dashboard and the OTA against the passenger's seat and off I went.
To me, it appears that the difference is more of a "fashionable" kind (pardon me the expression - I hope you understand what I'm trying to say  ). The SCT has a lot of theoretical disadvantages such as its larger central obstruction, its inability to collimate the secondary, more optical surfaces, longer cool down etc. But in the end this is hardly noticeable at the eyepiece. Remember when doing a side-by-side to use the same eyepieces!
Cheers,
Peter
--------------------
18" f/4.45 PeterDob
40mm Siebert VP Echelon 2" binoviewer
2x 36mm Siebert Observatory, 2x 24mm ES 82°, 2x 9,9mm Siebert Starsplitter
Nexus 100 with a couple of 21mm Siebert Ultrawide
www.astronomydrawings.com
Edited by peter-nexstar (07/18/06 04:09 AM)
|
Foehammer
professor emeritus
Reged: 06/29/06
Posts: 546
Loc: Cyprus
|
|
i 've also had a chance to do a side by side of an 8" LX90 against my C8N on both moon and jupiter...the view from the LX90 was noticably "darker" than the newt and to my surprise the LX90 showed very little detail on Jupiter compared to my C8N showing cloud bands and festoons... I honestly thought that the CAT would perform much better and i was quite shocked. Set up was at the same time and cooltime was ~ 1 hour on a fairly good night with good seeing. Eyepieces were of identical quality.
--------------------
Regards,
Agapios Elia
www.agapioselia.com
C9,25& DBK21
|
mark cowan
Vendor (Veritas Optics)
Reged: 06/03/05
Posts: 3427
Loc: salem, OR
|
|
Well, there's always the exception to the general rule. 
3 years back at OSP I was shocked (literally) when I compared my views of Mars through my homebuilt (and optically flawless) 8" f/6 Dob to that from a nearby Celestron C8 (or C11?) manned by some very enthusiastic, uhm, novices. There was no comparison at all.
I was friendly, said something like "that's nice" and held my real opinion. I invited them to the 8" but they crashed too early.
It reminded me of every other SCT I've looked through, and it's just darn sad.
I like the optical premise of the SCT, but you know when Bob Goff was still around he'd occasionally refigure commericial SCTs, and then they'd work like you'd expect from theory.
Best,
Mark Cowan
Salem, OR
|
PeterDob
sage
Reged: 07/29/05
Posts: 428
Loc: Carů, Italy
|
|
The problem with many SCT owners is that they don't bother about collimation at all. A friend in my club also has a Nexstar8 and he was really surprised when I told him why it has three screws up front. It is also a fact that a lot of SCTs are still being sold with poor-quality optics and a badly aligned primary. One of the biggest disadvantages I found on my SCT was the focuser. It was nearly impossible to achieve the perfect focus, until I got the idea from someone else on CN to stick a jar lid to the focuser knob. From then on it worked perfectly. Focusing on an SCT also requires a bit of a habit because you need to focus just a little beyond perfect focus and then let the mirror "fall" back.
Talking about planets, I've actually rarely seen more detail on them with my 14" (although superb 0.98 Strehl Woden mirror - well collimated) than with my Nexstar. And that's because we rarely get good seeing over here. On top of that, a 14" gathers so much light that at lower magnifications you need to play with filters or grab for your sunglasses.
Observation comfort. With an SCT, just take a chair and make yourself comfortable at all angles. Observing with a Dob can be a painful experience for back and neck when not at the perfect height for either standing up or sitting on a chair. Of course, there are some very nice and comfortable observing chairs around. But how much do they cost? Well, I'm actually digging a hole for myself here because I've actually built my own observing chair from a couple of pieces of wood and a few bolts. Cost me about $60. 
And last but not least, the SCT is an f/10. Saves a million on eyepieces!
Cheers,
Peter
--------------------
18" f/4.45 PeterDob
40mm Siebert VP Echelon 2" binoviewer
2x 36mm Siebert Observatory, 2x 24mm ES 82°, 2x 9,9mm Siebert Starsplitter
Nexus 100 with a couple of 21mm Siebert Ultrawide
www.astronomydrawings.com
|
BluewaterObserva
Postmaster
Reged: 05/18/04
Posts: 5748
|
|
My advice is to go to more star parties.
This is so contrary to my own experiences.
I do think many SCT's are never truly focused, it is tricky and an acquired skill.
I'd do some more comparisons. In the end you have to rely on your own experiences though. I don't know if I have been lucky to have looked through more experienced SCT owners scopes or what.
But most of the time all 8" scopes are about dead even at the eye piece regaurdless of scope type.
I have seen times when an 8" dob has slightly edged out an SCT but I have also seen times when the 8" SCT edges out the dobs.
I don't know what to think when I read threads like this with so many postings contrary to my own experiences.
To the originator I do suggest some addition comparisons. As far as contrast goes, The additional focal length alone tends to make for a much darker background sky in the SCT than an F/6 dob.
I often wonder if the general climate out here in the west / southwest US helps the SCT out some. Not sure. but I think some additional comparisons ae in order by the originator of this thread.
|
conus
Post Laureate
Reged: 10/12/03
Posts: 3038
Loc: OC, Calif
|
|
Last year I sold my C9.25 and just recently bought a 12" reflector. I'm definitely keeping the larger scope, but I'm also going to replace the SCT. Although the larger reflector does show a little more on some objects, the difference is slight and there's nothing like relaxing in a chair and sweeping throughthe Milky Way with a well collimated C9.25 and a 2" eyepiece.
--------------------
Steve R.
Orion XT12
Fujinon 10x42
Oberwerk 12x60
Garrett Optical 15x70
http://www.telescopesinhistory.com
|
reflector74
Pooh-Bah
Reged: 10/09/05
Posts: 1249
Loc: Milky Way Galaxy, Orion Arm
|
|
Quote:
Last year I sold my C9.25 and just recently bought a 12" reflector. I'm definitely keeping the larger scope, but I'm also going to replace the SCT. Although the larger reflector does show a little more on some objects, the difference is slight and there's nothing like relaxing in a chair and sweeping throughthe Milky Way with a well collimated C9.25 and a 2" eyepiece.
The difference in light gathering isn't all that subtle.
--------------------
Two eyes and a preference to use both
|
conus
Post Laureate
Reged: 10/12/03
Posts: 3038
Loc: OC, Calif
|
|
Quote:
The difference in light gathering isn't all that subtle.
Two and three quarters of an inch? It's not going to blow anyone away. Sure there's a difference-- a few more resolved stars in the globulars, a little more planetary detail and slightly brighter galaxies. Like I said, I'll keep the 12, but if I could have only one scope-- a Celestron C9.25 and a 12" dob, the SCT would win hands down. Admittedly some of this has to do with my fondness for chairs. At any rate, my only regret in buying the 12 is that when it comes time to get more aperture the move to a 15" would only be 3 inches. Originally I had planned on moving up in increments of 4 inches. Astromart sure can mess up those long range plans.
--------------------
Steve R.
Orion XT12
Fujinon 10x42
Oberwerk 12x60
Garrett Optical 15x70
http://www.telescopesinhistory.com
|
George Methvin
Pooh-Bah
Reged: 01/30/06
Posts: 1083
Loc: Central Texas
|
|
Same with me the views through my 8 inch dob are a little better then through my C-8 both have great optic but the C-8 is just easyer and more fun to use,it easyer on my back and I love the tracking and goto of the mount. If I have to keep just one it would be the C-8.
|
Alan French
Night Owl
Reged: 01/28/05
Posts: 4009
Loc: Upstate NY
|
|
I certainly think folks should do their own comparisons, and highly recommend visiting conventions and star parties to check out a variety of telescopes.
I've attended 85 conventions and many more local star parties since 1968. While the optics in SCTs can be quite good, I have yet to find one that gives what I would consider exceptional planetary views. In my experience, an 8" SCT simply does not provide the level of detail visible in a guality 8" Newtonian.
Clear skies, Alan
|
Previous
Index
Next
Threaded
Edit
Reply
Quote
[Re: 