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C6 or 6" Intes MCT or C6-R?

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#1 SimonL

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Posted 29 October 2013 - 04:38 PM

So would you recommend a SCT/MCT/refractor?

#2 Jan Owen

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Posted 29 October 2013 - 05:15 PM

Any of those could be a good choice.

But to make the *right* choice, it depends a lot on what types of objects you want to observe, and where you plan to use the scope most of the time...

#3 SimonL

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Posted 29 October 2013 - 05:24 PM

The messier objects and planets in my backyard (urban) most of the time. I see you have refractors , SCT and Newtonian.
Which is your preferred scope?

#4 Eddgie

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Posted 29 October 2013 - 05:26 PM

Well, of course if you can afford $5000 for a 6" APO and another $2000 for a good used mount, then the 6" APO is going to be by far and away the best performing scope.

It will have better contrast on planets, better deep sky performance, and a far wider true field than these other designs.

A 6" acromat though is not the same thing as a 6" APO.

And don't let people convince you that you can turn a 6" acromat into a 6" APO with a filter. The damage from CA is not just the color fringing, but rather the energy removed from the Airy Disk, which lowers the performance to no better than a 4.5" to 5" ED refractor. The only thing left is the wide field performance.

If you are comparing 6" f/10 MCT to 6" SCT, then because the new Celestron scopes seem to have excellent quality, the difference will not be all that much.

If you like to do planets, an older 6" f/15 Intes will beat anything either of the f/10 scopes.

There is an option between all of these though.

If you can find a used MN66, you get the excellent contrast and wide field performance of a 6" APO, but you still have to ante up for a medium size mount.

So, you are comparing apples to go carts here by including 6" refractors because to get one with good performace, it needs to be an APO and this means that with the mount, you will spend 10 times as much as you would for a 6" SCT.

The big, fast achromats are simply not very good telescopes for much other than wide field, but if that is what you want, and if you can afford the mount, then go for it.

But a used MN66 is such a better scope than all of these other choices, that if you are seriously considering a 6" refractor, do yourself a favor and get the 6" Mak Newt.

#5 SimonL

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Posted 29 October 2013 - 05:32 PM

Well these are all sort of the same in cost. I could add an 8" f/5 Newtonian to the mix. This should be good for wide fields plus all the above but much bulkier than a SCT or MCT.

#6 SimonL

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Posted 29 October 2013 - 05:33 PM

And there are used C8's.

#7 SimonL

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Posted 29 October 2013 - 05:40 PM

There are good Skywatcher 6" achromats that perform close to older 6" f/8 AP apo.

#8 BillP

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Posted 29 October 2013 - 06:04 PM

Well these are all sort of the same in cost. I could add an 8" f/5 Newtonian to the mix. This should be good for wide fields plus all the above but much bulkier than a SCT or MCT.


All the scopes you mention have their pros and cons. So it all just depends on your preferences in the mix.

A C6-R is a big scope. The mount needs to be tall with legs extended if you are viewing anything near the zenith...otherwise you will be on the ground trying to access the eyepiece. :lol: It will do great with most everything, but will show color on planetary or lunar viewing which some folks do not like. You will get a 2.2 degree TFOV as max with a 2" eyepiece.

The SCTs and MCTs are closed tube and will have thermal equillibrium difficulties if your outdoor temps vary much. But they are small and convenient. Most have long focal ratios though so at ther native f/10 or f/15 the most TFOV you will get is 1.75 to 1.2 degrees with a 2" eyepiece...and their central baffles may not allow even that. Higher planetary magnifications though they can be great when in thermal equillibrium, better than the achromat for sure.

The 8" f/5 Newt is the biggest and heaviest probably of the group. It will need a Paracorr if you plan wide field. The nice thing though is that with something like a 40mm XW or 31T5 you can get a good, bright, and large patch of sky, around 2.3 to 2.5 degrees. Exit pupil with the 40mm and Paracorr is a bit over 7mm so better choice would be the 31T5 probably. The f/5 will also have a smaller central obstruction by far compared to that on say the SCT.

So just all depends on what you are after. The extra light pull of the 8" though over the 6" is significant, around 1.8x more light gathering. Extra resoltion as well. I've had all the other types of instruments, and now am experimenting with an 8" f/5 on a GEM mount (having a rotating tube is a must if on a GEM). Right now I am much preferring the 8" f/5 over the others because it has a good wide TFOV capability and gathers enough more light to make stuff like fainter Globs much more interesting than what a 6" SCT or MCT will show. If bulk is no issue then IMO the 8" Newt is best all around, if you want to maximize protability than the Celestron C6 is superb and gives a bright image as well. Would probably also get a .6x focal reducer with it though to flatten some of its field curvature out and give it better wide field performance.

#9 Eddgie

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Posted 29 October 2013 - 06:45 PM

I have owned both, and I can tell you without any reservation that a 6" f/8 achromat can in no way compare to a 6" APO.

Have owned three 6" f/8s, and an MN66 is a far better telescope.

But get what you like. It sounds like you may already have a refractor in mind. They are inexpensive and if you have a way to mount it, then go for it.

And if you decide you want to sell it, there will be someone else that will take it off of your hands.

#10 Jan Owen

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Posted 29 October 2013 - 07:12 PM

I'm not certain I have a single most favorite scope... The scopes I have now have been acquired for a variety of different uses. Basically, most of them were bought to address specific interests of mine... So, within their own realm, they're each favorites...

Frankly, I probably use the 8" Newtonian the most. It has exceptional optics, and *enough* aperture to do double duty for either lunar/planetary, OR DSO's...

But when I want to get more serious about DSO's in general, I'll always choose the 12" (and it does put up superb lunar/planetary images as well). On the other hand, if I were to choose just the Double Cluster (a personal favorite object which I can easily spend an entire night on alone), I'm about as likely to grab any of them... Each one delivers the goods in their own special way...

But then, there's the 10" SCT, which also has excellent optics (replacement optics for the original set), can deliver stunning images (I do pay meticulous attention to collimation & getting & keeping the optics fully equilibrated with the surrounding air), so, given it's compact size for the aperture, and great images, it could steal your heart when the conditions are right...

I guess I sounded like a politician, there... Never gave you a clear-cut single answer... That's because I'm always wavering back & forth between my scopes as to which is my favorite...

BUT, if I can only recommend one of them, I suppose it'd be the 8" Newtonian, assuming you take the time to assemble one with equal optics & mechanicals...

While I was gone, I see you've also received some superb assistance from others here. This is a GREAT place to come for answers to questions like yours... Some very really well-experienced and helpful folks give of their time selflessly to help flesh out a variety of possible solutions. Hard to find a better place for that than here.

#11 Jan Owen

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Posted 29 October 2013 - 10:55 PM

Now, for a more direct answer.

Directly to your interests, the messier objects and planets from an urban back yard, from the specific telescopes you have asked about, I'd probably recommend the Intes (or Intes Micro) MCT, if it's an f/10 (the f/15 would be slightly better for planets, and the f/10, with it's wider field, a bit better for the Messier Objects. The C6R would be no slouch on the Messier objects, either. But the other two would probably edge it slightly on the moon & planets, though it would be close.

For a a modest sum more, though, you could buy an 8" SCT, or a REALLY nice 8" f/6 Newtonian (which will take you deeper on the DSO's, show more planetary detail)... Those pesky Newtonians, if assembled from the right parts, deliver amazing views that, with the aid of a Paracorr, can deliver images you'd SWEAR were from an APO.

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#12 SimonL

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Posted 30 October 2013 - 11:56 AM

For the money I could get a C8 or C6R.

#13 Joe Aguiar

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Posted 30 October 2013 - 12:30 PM

wow tough call
the refractor is long and will need a decend mount so it will weight abit, but its good overall it has some colour but decent optics and vies

the mak will take longer to cool down and long FL means crisper views but fov is small, cooldown time may be 1 hr to 1.5 hrs

sct will be maybe the middle of both the other scopes so my option will be this one for u

#14 Jan Owen

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Posted 30 October 2013 - 12:33 PM

If cost is a major issue, the C6R will deliver a lot for the money... Depends on how much chromatic aberration bothers you, when you're viewing bright objects... For most DSO's there won't BE any chromatic aberration, and the views will be quite nice... They are a bit long and more cumbersome, but there are a lot of happy C6R owners out there.

The SCT is more compact, and can deliver great images. They can be a little slow to equilibrate, compared to the Newt or refractor, but active cooling can be a big help, if the scope has this, or if it can easily be added. And the compact size can be a real blessing during setup and takedown.

The Newt will deliver slightly more aesthetically pleasing images, and a wider field for DSO's, at the expense of a longer tube. And, the Newt, if it's similar to mine, will also be a little more expensive (much of which comes from the Paracorr & Nagler eyepieces, and not the cost of the scope, but without which a level of the superior aesthetics would be lost).

The MCT will have superb views, similar to the Newt, with sharp images across the field, at low or high magnification, and no visually meaningful aberrations. It is compact like an SCT, but more expensive, and cooldown will be as long as an SCT or longer. If you're patient, and don't live where the temperature changes dramatically in a short time, they can be stunning.

#15 dweller25

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Posted 30 October 2013 - 12:37 PM

Whilst it's not on the OP's list but keeping to a 6" aperture - I would get a 6" F/8 Dobsonian with excellent optics.

#16 Stelios

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Posted 30 October 2013 - 02:45 PM

For the money I could get a C8 or C6R.


A C8 (8" SCT) is, IMO, a *FAR* superior telescope to a C6R.

First of all the obvious: It has higher light grasp and resolution. Contrast is comparable. It has no false color unlike the *ginormous* false color of the C6R.

But there are the less obvious as well:

1) The C8 you can observe in comfort seated. The C6R will put you in all kinds of contortionistic positions.
2) The C6R requires a bigger mount than the C8. A CG-5 will hold a C8 like a baby, but trembles under the C6R.

The one advantage the C6R has is larger field of view.

Frankly, the main C6R appeal is that it's cheap. If you can afford something else, go that way.

#17 SimonL

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Posted 31 October 2013 - 02:26 PM

Well I like a C8 but I have to use it in the winter. There could be tube currents and long cool down times.
Also with UHC or OIII filter will C6-R be same as an 6" APO?

#18 Eric63

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Posted 31 October 2013 - 02:36 PM

Winter is an issue where I live, but I simply plan ahead. I put my Mak (still in its case) outside (or in the trunk of my car) an hour before observing. If I change my mind later, I just bring it back in.

Eric

#19 Jan Owen

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Posted 31 October 2013 - 03:28 PM

You can't get an achromat to APO performance via filters (but I haven't seen any test results from using narrow passband filters in side by side comparisons between an APO and an achromat).

You can get fairly close with a Chromacor, but they aren't in regular production any longer, to the best of my knowledge, and aren't inexpensive (except in comparison to the price difference between an achro and APO telescope)...

#20 azure1961p

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Posted 31 October 2013 - 08:14 PM

I've found an hour with my C6 in the dead of winter is enough equilibrium time. I personally wouldn't even remotely consider that 6" achro unless you are happy at low power. A C8 can cool down very fast so I'm told - 30 minutes) with a Lymax device that essentially blows outside air into the OTA .

I haven't done it specifically with that 6" achro but if you are entertaining ideas of great 300x shots of Plato or Mars you might want to lose the achro idea all together - certainly at that focal ratio/aperture. There are too many other far better choices.

Pete

#21 Jan Owen

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Posted 31 October 2013 - 08:59 PM

You bring up a good point about the Lymax SCT cooler... I have one for my 10", and it has transformed that scope from one which often NEVER equilibrated all night long, to one that's ready to rock in less than an hour. And if you have to stop and catch the scope up on an evening when the temperatures are falling quickly, it doesn't take long after the initial big cooldown (but you may find yourself repeating the exercise several times through a long night)... Couldn't live without my Lymax and the Celestron f/6.3 reducer/corrector...

#22 spencerj

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Posted 01 November 2013 - 09:41 AM

I have always been partial to the Intes and Intes Micro scopes, because . . . well . . . they are just cool. I have always liked the industrial tank-like build and excellent optics. Over the last 10 years, I have always owned at least one. I don't see that streak ending anytime soon.

Sure cool down is something you have to be aware of, but that is the case with all scopes. Eddgie is right about the MN66. In the 6" class, you will not find a more versatile and optically excellent scope for the money (especially if you find a good one with an upgraded focuser on the used market).

#23 RichD

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Posted 01 November 2013 - 10:44 AM

The MN66's are wonderful scopes. I think for the price and all round ability they are very hard to beat.

Used, they represent a great bargain.

#24 Thomas A Davis

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Posted 01 November 2013 - 02:19 PM

Ditto that. I owned one, and it was as close to a 6" APO as
I've seen in a non-refractor design. Also, they are lighter
than the Intes MN61, so less of a mount is needed for it.

Tom

#25 SimonL

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Posted 03 November 2013 - 06:09 PM

I think the helical focuser and lack of range and small CO is a problem for the Intes MN scopes for wide fields and imaging.






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