Celestron 6" refractor or 8" reflector?

[kosh]

HI all,

Just looking for some opinions about a purchase that i'm stweing over.
I have a budget of under $2k and i'm not sure which to go for. I can either purchase a Celestron C6-RGT f/8 achromatic refractor 6" or the C8-NGT 8" Newt at f/5. Both are on EQ5 mounts and have GOTO installed. What I need is something for DSO mainly, and would like to get into Astrophotography later on aswell.
I just don't want to buy another scope later. Is it all about apeture size or other things also?
I plan to use it for visual and photo eventually.

Any thoughts?
:confuse2:

[ving]

hi, welcome aboard... an expert will arive soon and give his/her opinion :)
heard of the rgt, but not seen any reviews on it. you searched for reviews yet?

[asimov]

Welcome.

[kosh]

boy have i ever ! :doh:

Only astronomics have any real info and they are also selling so I don't take too much stock in that. I can't really find anything 'specific' to the advanced series but the 8" OTA seems well liked. Just very confusing. I really want to make the expenditure count, if you know what i mean. I'd love to have a bigger budget but, well, ya'know.

Thanks for the welcome too!

[atalas]

Hi Kosh :welcome: to IIS ! without any doubt in my mind I would say go the
8" newt . The only other way around your budget would be to go used.
e.g . I think we have at this time a GPDX/Skysensor for sale for $1500.00 and you could pick up a 8" OTA for $500.00 I'm sure. The Vixen is a far superior mount to the Celenstron. Anyhow good luck on your hunt .


Louie :thumbsup:

[dhumpie]

I agree with Louie. The 6" refractor is a beast that needs at least an EQ6 mount. And the 8" newt will be color free while you will get some nice chromatic abberation in the 6" refractor. Its a no brainer actually :)

Darren

[westsky]

Hi Kosh , Louie has the right idea, buy the Vixen and SS2K (if it's still for sale), much better than the ASGT mount, I know as I have both.
look around and by an 8" newt then your'e all set for the astrophotography down the track.
The SS2k would have to be the most underated controller on the market, I have had mine for about 5 yrs and will never sell it.
cheers
david.

[Stu]

Well I am a self confessed refractor nut and I actually agree with the other very wise posts. The newt would be a better choice. But the F5 newt will have more edge of field coma and will be harder to collimate properly than a longer focal length.

Here my 2 cents worth...

Astrophotography:
The 6" refractor is excellent for visual work but doesn't quite fit the requirement for most long-ish exposure astrophotography (in my opinion). The false color will show up on long exposures unless you use color filters and refocus for each filter, which is possible but...
If you were dead set keen on photography then an ED 80mm refractor ($599-$899 depending on which brand name is stamped on it) and the second hand GPDX/skysensor or a new Meade LXD75 with Autostar ($1450 with a free 6" newt) would be awesome. You really need a good mount and a good lens.

Deep Sky:
Buy a Dob. Nothing else comes close for $2K.

Half way in between:
The Meade LXD75 8" schmidt-newt is large and coma corrected but at $2200 just out of your price range. The Celestron C8-NGT is a 8" F6 on an EQ4 with lots of special mods to make it more stable is $2170. You could get it if you lived not to far north. The mount doesn't quite tilt enough without replacing one of the pins (I think there was a review in one of the local mags that mentioned this a few issues back).


Also, feel free to buy something completely different ('cause then I might get the skysensor ;) ).

[ving]

just get a teleview paracorr to correct the coma and your set with the 8" reflector :)

[kosh]

Ok, thanks for all your help guys, it looks like a newt 8" or so. :cool:

Stu, where did you say I could get an LXD75 +6"newt w/Autostar for $1450?
If that's accurate, i'd really, really like to know. It would certainly be worth a look at.

[mickoking]

G'day Kosh

IT is a perennial question you pose so I solved it by buying both an 120mm Refractor and a 250mm Dob. Im purely a visual observer so I have no need for fancy computer drives so the above mentioned solution was quite economical.

:D

[janoskiss]

:welcome: mickoking!

So, you have both! Tell us: which one is better?

[astrojase]

Howdy Kosh ;-)

I concur with mickoking - in my case I purchased a 60mm (loved it and then pift it!), 8" Newt (loved it, not for long though!!!), then a 90mm Achromatic (Double lens refractor reducing distorted colours - still got it!), 10" Newt (loving it) and saving up for a 20"...!

Get the drift...! 8" will get you a good start, 10" will blow your mind more!

Either way, you should come in under $2k...you will have more change with a Dobsonian mount - Equatorial more $ + more versatile...or, spend a bit more and get both types of mounts....dobs go relatively cheap!

Cheers and clear skies,
me.

[kosh]

So I can buy a 10" dob and then upgrade to an EQ mount and tripod later and still fit the 10" dob OTA on the new mount?

What kind of mount would it have to be to handle the wieght?

[mickoking]

Strait up I prefer the refractor purely because of the contrast. But for faint fuzzies it is the Dob. That is why if your budget extends that far it is good to have more than one Scope. No one telescope can do everything. I also have an 80mm short tube which is good for a quick sesh and wide angle viewing. It can be carried out side with one hand and is ready to go strait away.

[[1ponders]]

Kosh its not so much the weight that is the problem for eq mounting (though that is a consideration) but the lever arm movement of such a long scope.

Think of it this way. If you hold a pencil between your thumb and forefinger and blow on the end of it from the side, it won't move much. But if you swap that pencil for say a one meter ruler (ignore the weight for the moment) and blow on the end of it its much harder for you to hold it without sideways movement than the pencil. That's lever arm movement . But its not just wind. Any movement of your mount (gears turning, mount settling) will be amplified along the scope, so for photographic work it makes taking images a real challenge. Even for visual work it can be a challenge. Oh and it doesn't just happen sideways, the same principle for up and down.

Its only an analogy but hopefully you get the idea. The longer (and weightier) the scope the stronger and more stable the mount needs to be.

So what sort of mount. Usually a fairly expensive one unfortunately :P. I have seen 10" mak newts mounted on LX75 (I'd hate to try to image with one and keep my hair, though some people do it successfully) and I've seen 10" reflectors mounted on EQ6s (hell I've seen a 12", the guys hair was pretty patchy though). IMHO an eq6 would be a minimum for success with a 10" scope if you are thinking imaging.

JMO

[asimov]

Paul, even though I fully understand the principal of lever arm action etc. your way of explaining it was simply spot on! Pure & simply well done mate.

[[1ponders]]

;) That's me, pure (ask my wife :lol: ) and simple :P :D:thumbsup:

[GrampianStars]

http://www.takahashiamerica.com/catalog/images/NJP_list.gif

A Tak NJP mount would handle the scope with ease :D

The NJP mount offers a high capacity (70lb load) platform for a variety of photo and visual uses requiring the use of two instruments. The PD-8XY motor drive has a built-in connection for an auto guider and a 10x sidereal high speed mode allows electric centering of an object in the field, rather than using the less accurate manual override. The NJP also uses a side loading plate to insure that as the mount is elevated and depressed for proper polar alignment, it moves in a straight line. No other manufacturer includes this unique, useful feature in their mount.

[acropolite]

Robert said
Just don't ask how much.....:jawdrop:

[kosh]

What about the Guan Sheng range of scopes that Andrews are selling.
Does anyone know much about the quality of those?
$899 8"newt w/Dual axis drives... could be an option.

[kosh]

$999 actually.

[dhumpie]

GS newts and dobs have very good to excellent mirror's for mass produced scopes. Many experienced observers (i.e. Geoff Gaherty, Phil Harrington and our own John Bambury) have commented that GS mirror's are fractionally better than Synta mirrors.

Darren