Author Topic: Newtonian vs RC?  (Read 320 times)

Sam Citadelle

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Newtonian vs RC?
« on: December 24, 2017, 08:06:33 PM »
I'm wanting to have a new larger aperture telescope... from the 12" to 14" range... and'm torn between the decision involving an imaging Newtonian and an RC telescope?

I was only hoping to have people's thoughts on the pros and cons of each.  My opinion is that the newtonian will be enjoyable for visual observing, as it has a much smaller obstruction compared to the RC, but the RC will be better for imaging.  My principal purpose is planetary and galaxy imaging.  I like that the RC's have considerably longer focal point for this purpose, but could I not use a 2x barlow using the newtonian of same aperture and also get that also?  I have heard folks say with the barlow, you have reduced your lighting, however... but why would this not be the situation with a longer focal length telescope, too?  Am I missing something?  I was considering the 14" ONTC newtonian by TS that seems excellent, but it's very long... just like 5.3 feet... but I consider a 14" truss-tube RC and it's extremely wide and heavy... like 65 pounds and 20" wide at the back... versus the 14" ONTC newtonian is only 55 pounds... I've purchased the Orion HDX110 mount using a weight limit of 110 pounds... to ensure 14" RC would be over 50 percent of the rated ability.  Are both of those telescopes too thick for this mount?  Should I be considering 12" rather?  But I am currently digressing....  Mostly, I was only wanting to hear thoughts about people's opinions involving the RC kind telescope versus Newtonian.  I now have the 9.25" EdgeHD Celestron... I got frustrated with all the glass corrector plate at front always fogging up during a long exposure... and Celestron doesn't make a focal reducer for it... and I've ended up just needing to purchase something different as a result... something without a glass corrector plate at front, and now I guess while I'm purchasing a new telescope, would like to buy one with as large a aperture as my mount could take.

It seems like hardly anyone does imaging with Newtonians?  It is obviously with APO refractors, RC's, SCT's... but nearly never Newtonians.  I'm curious why this is?  Because, it just appears to me if you could get a fantastic photo from one, then you would have the best of both worlds... better visual observing and very good photos too.  I'd love to picture galaxies using it, therefore that a longer focal length could be desirable, and that is why I'm wondering if I could simply use the barlow for this, rather than purchasing an RC mainly for it's longer focal length?  I've gotten very good at collimating both Newtonian and SCT telescoepes and may collimatethem in a matter of a few minutes... or even seconds... but read somewhere that collimating the RC is a 2-3 hour process... Is that true???  That alone makes me hesistant to get one... Any thoughts would be appreciated...

Thanks,
James



acbanlota

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Re: Newtonian vs RC?
« Reply #1 on: December 31, 2017, 08:16:31 AM »
Hi, James.

If you decide to pick out the TS Newtonian OTA, which focuser are you planning to buy with it?

Pat Young

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Re: Newtonian vs RC?
« Reply #2 on: January 04, 2018, 09:52:40 AM »
RCs are chosen by some rather than large Newts because they're more compact. Among other things that's easier on the mount, sheer length and bulk matters. They can be hard to collimate. There's a difference between the low end RCs and the expensive premium ones in this regard. The very precise high quality mechanical components of the premium versions make a large difference. But any RC will be harder to collimate than a Newtonian or SCT.

Another advantage of the RC for imaging is generally longer backfocus, for things like off axis guiders and filter wheels.

Visual and AP of DSOs are completely different because of the "sensors". Your short exposure eyes need a lot of aperture to gather light really fast, but are forgiving of errors like tracking and aberrations. .005mm pixels gathering light for some time are extremely unforgiving. Most people who do both have different scopes for each. Generally RCs are used for imaging, Newtonians for visual.

Planetary is more like visual (short exposures), imaging DSOs is a unique thing. Long exposures change everything.

RCs have a large central obstruction which reduces contrast. An issue for visual, easily dealt with in processing for imaging DSOs. If you want to image with a Newt, you'll need a coma corrector. With an RC a field flattener can be useful.

This is not a question of which is technically "better". More a matter of personal needs and personal taste.

lolenokind

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Re: Newtonian vs RC?
« Reply #3 on: January 07, 2018, 11:01:04 PM »
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Hi, James.

If you decide to pick out the TS Newtonian OTA, which focuser are you planning to buy with it?


I was going to get the Starlight Feathertouch...

tamamatte

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Re: Newtonian vs RC?
« Reply #4 on: January 10, 2018, 10:57:21 AM »
Quote
RCs are chosen by some rather than large Newts because they're more compact. Among other things that's easier on the mount, sheer length and bulk matters. They can be hard to collimate. There's a difference between the low end RCs and the expensive premium ones in this regard. The very precise high quality mechanical components of the premium versions make a large difference. But any RC will be harder to collimate than a Newtonian or SCT.

Another advantage of the RC for imaging is generally longer backfocus, for things like off axis guiders and filter wheels.

Visual and AP of DSOs are completely different because of the "sensors". Your short exposure eyes need a lot of aperture to gather light really fast, but are forgiving of errors like tracking and aberrations. .005mm pixels gathering light for some time are extremely unforgiving. Most people who do both have different scopes for each. Generally RCs are used for imaging, Newtonians for visual.

Planetary is more like visual (short exposures), imaging DSOs is a unique thing. Long exposures change everything.

RCs have a large central obstruction which reduces contrast. An issue for visual, easily dealt with in processing for imaging DSOs. If you want to image with a Newt, you'll need a coma corrector. With an RC a field flattener can be useful.

This is not a question of which is technically "better". More a matter of personal needs and personal taste.

I was looking at the Astro-Tech Truss Tube 14" RC for about $5,800... not sure if that one is considered high quality or low-end... as you can get some RC's for $400 and others for $25,000... it seems to sit (price-wise) kind of in the middle? Although a little on the lower-side... It's hard tofind any reviews so I appreciate your comments. If it is considered a not very well made one, I'd rather buy a well-made Newtonian than a cheaply made RC...

Richard Reed

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Re: Newtonian vs RC?
« Reply #5 on: January 10, 2018, 10:57:44 PM »
Imaging newtonians must be made very well to hold collimation. And the better ones are really made for imaging, not visual. They need good quality correctors, and excellent focusers, motorized is best. I think you will be best off to get a dedicated imaging scope if you want the least problems with setting up for imaging. My AGO newt has never had an eyepiece in it, and doubt I could find focus anyways.  My Epsilon 160 on the other hand is a wonderful wide field visual as well as fast astrograph. But I have only ever had an eyepiece in it one time.

I have no idea about your mount, but a 5' long OTA is huge and requires a very good mount. The AGO is 4' long and I would never consider putting it on anything less than my AP1200. Lots of moment arm with that thing swings around let alone if there is a slight breeze.

Then you have the ergonomics of where the eyepiece is with newts on a GEM. Gets into uncomfortable positions where as something like a SCT or RC would at least have it at the rear of the scope.

I also have a 10" AstroTec RC that is reduced to F/6 1545mm and make a nice compact imaging set up, at least compared to the big newt.  My AP900 handles it just fine. Again I have never used it for visual as it is mainly intended as an astrograph.

My opinion for what its worth, if you want to get serious about imaging, buy a quality dedicated scope and set it up just for imaging. There are plenty of nice visual scopes out there for way less money that will do the job just as well, and probably better for that. Then while imaging you can do visual with the other scope. Best of both.

Good luck on this slippery slope

Dean

I have some recent images made with both my AGO newt and 10" RC at astroimagers.com/DeanS

ulatimhan

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Re: Newtonian vs RC?
« Reply #6 on: January 11, 2018, 10:58:34 AM »
Quote
Quote

Hi, James.

If you decide to pick out the TS Newtonian OTA, which focuser are you planning to buy with it?


I was going to get the Starlight Feathertouch...
2" or 3"?

Richard Acosta

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Re: Newtonian vs RC?
« Reply #7 on: January 12, 2018, 03:04:19 AM »
I'm not the most qualified person to comment, James. I don't do imaging at all. However, from now and then, I read some posts from guys who are quite happy with their 8" f/4 Newtonian reflectors, for example.
The TS 14" f/4.6 Newtonian reflector that you are eying seems to come with great optics. Orion UK optics, you know. But it is huge. Do you know how much it weighs?

Nathan Harper

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Re: Newtonian vs RC?
« Reply #8 on: January 17, 2018, 12:34:19 AM »
Quote
Quote

RCs are chosen by some rather than large Newts because they're more compact. Among other things that's easier on the mount, sheer length and bulk matters. They can be hard to collimate. There's a difference between the low end RCs and the expensive premium ones in this regard. The very precise high quality mechanical components of the premium versions make a large difference. But any RC will be harder to collimate than a Newtonian or SCT.

Another advantage of the RC for imaging is generally longer backfocus, for things like off axis guiders and filter wheels.

Visual and AP of DSOs are completely different because of the "sensors". Your short exposure eyes need a lot of aperture to gather light really fast, but are forgiving of errors like tracking and aberrations. .005mm pixels gathering light for some time are extremely unforgiving. Most people who do both have different scopes for each. Generally RCs are used for imaging, Newtonians for visual.

Planetary is more like visual (short exposures), imaging DSOs is a unique thing. Long exposures change everything.

RCs have a large central obstruction which reduces contrast. An issue for visual, easily dealt with in processing for imaging DSOs. If you want to image with a Newt, you'll need a coma corrector. With an RC a field flattener can be useful.

This is not a question of which is technically "better". More a matter of personal needs and personal taste.

I was looking at the Astro-Tech Truss Tube 14" RC for about $5,800... not sure if that one is considered high quality or low-end... as you can get some RC's for $400 and others for $25,000... it seems to sit (price-wise) kind of in the middle? Although a little on the lower-side... It's hard tofind any reviews so I appreciate your comments. If it is considered a not very well made one, I'd rather buy a well-made Newtonian than a cheaply made RC...
The 14 inch truss tube is one of the better of the low end RCs. But it's still not a premium one, the price is high because it's a 14 inch. At least they've now decoupled the mirror from the focuser (you don't want one of the old models). It's still not this.

http://www.knaeble-e...om/telescope-3/

Only about 4 times as expensive. <smile>

I have that "$400" RC, the 6 inch (sold under a variety of labels). Lovely optics, marginal mechanicals. I've spent a little over $1200 total, and hours collimating it (it was badly miscollimated on receipt), now it's a good scope. But not a Knaebel, which no doubt arrives perfectly collimated, and holds it well.

Where these scopes are concerned, be they Newtonians or RCs, you generally get what you pay for. There are no great bargains. Post #6 above is excellent.

Owen Khan

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Re: Newtonian vs RC?
« Reply #9 on: January 30, 2018, 12:14:55 AM »
Quote
Quote

RCs are chosen by some rather than large Newts because they're more compact. Among other things that's easier on the mount, sheer length and bulk matters. They can be hard to collimate. There's a difference between the low end RCs and the expensive premium ones in this regard. The very precise high quality mechanical components of the premium versions make a large difference. But any RC will be harder to collimate than a Newtonian or SCT.

Another advantage of the RC for imaging is generally longer backfocus, for things like off axis guiders and filter wheels.

Visual and AP of DSOs are completely different because of the "sensors". Your short exposure eyes need a lot of aperture to gather light really fast, but are forgiving of errors like tracking and aberrations. .005mm pixels gathering light for some time are extremely unforgiving. Most people who do both have different scopes for each. Generally RCs are used for imaging, Newtonians for visual.

Planetary is more like visual (short exposures), imaging DSOs is a unique thing. Long exposures change everything.

RCs have a large central obstruction which reduces contrast. An issue for visual, easily dealt with in processing for imaging DSOs. If you want to image with a Newt, you'll need a coma corrector. With an RC a field flattener can be useful.

This is not a question of which is technically "better". More a matter of personal needs and personal taste.

I was looking at the Astro-Tech Truss Tube 14" RC for about $5,800... not sure if that one is considered high quality or low-end... as you can get some RC's for $400 and others for $25,000... it seems to sit (price-wise) kind of in the middle? Although a little on the lower-side... It's hard tofind any reviews so I appreciate your comments. If it is considered a not very well made one, I'd rather buy a well-made Newtonian than a cheaply made RC...
I think the new version of the AstroTech truss RC scopes are good for the money, however a DK from Planewave or iDK from AGO would be considered top of the line.

As for newts, the TS is not what I would consider near top of the line. The ASA is considered to be up there, along with the UK orion optics AG scopes.  My AGO newt was the first production 12.5" that he made, and it turned out to be more difficult that he thought. Ended up learning a lot, we both did, after the first one had some issues. He ended up making me a completely new scope with improvements he thought was needed. The new scope is absolutely great, but cost him much more to make. He only sold about 4 of the 12" and maybe 4 of the 10" I think and had removed them from his standard product line up as they are expensive to make, and a limited market. And tricky to collimate for large chips, just like most astrographs really. I use 8300 chips that are considered small in todays standards so I do not have any problems collimating either of my scopes.

Again just my opinion, and worth that you paid

Dean

reapriavoland

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Re: Newtonian vs RC?
« Reply #10 on: January 31, 2018, 02:10:35 AM »
Quote
Quote

Quote

RCs are chosen by some rather than large Newts because they're more compact. Among other things that's easier on the mount, sheer length and bulk matters. They can be hard to collimate. There's a difference between the low end RCs and the expensive premium ones in this regard. The very precise high quality mechanical components of the premium versions make a large difference. But any RC will be harder to collimate than a Newtonian or SCT.

Another advantage of the RC for imaging is generally longer backfocus, for things like off axis guiders and filter wheels.

Visual and AP of DSOs are completely different because of the "sensors". Your short exposure eyes need a lot of aperture to gather light really fast, but are forgiving of errors like tracking and aberrations. .005mm pixels gathering light for some time are extremely unforgiving. Most people who do both have different scopes for each. Generally RCs are used for imaging, Newtonians for visual.

Planetary is more like visual (short exposures), imaging DSOs is a unique thing. Long exposures change everything.

RCs have a large central obstruction which reduces contrast. An issue for visual, easily dealt with in processing for imaging DSOs. If you want to image with a Newt, you'll need a coma corrector. With an RC a field flattener can be useful.

This is not a question of which is technically "better". More a matter of personal needs and personal taste.

I was looking at the Astro-Tech Truss Tube 14" RC for about $5,800... not sure if that one is considered high quality or low-end... as you can get some RC's for $400 and others for $25,000... it seems to sit (price-wise) kind of in the middle? Although a little on the lower-side... It's hard tofind any reviews so I appreciate your comments. If it is considered a not very well made one, I'd rather buy a well-made Newtonian than a cheaply made RC...
I think the new version of the AstroTech truss RC scopes are good for the money, however a DK from Planewave or iDK from AGO would be considered top of the line.

As for newts, the TS is not what I would consider near top of the line. The ASA is considered to be up there, along with the UK orion optics AG scopes.  My AGO newt was the first production 12.5" that he made, and it turned out to be more difficult that he thought. Ended up learning a lot, we both did, after the first one had some issues. He ended up making me a completely new scope with improvements he thought was needed. The new scope is absolutely great, but cost him much more to make. He only sold about 4 of the 12" and maybe 4 of the 10" I think and had removed them from his standard product line up as they are expensive to make, and a limited market. And tricky to collimate for large chips, just like most astrographs really. I use 8300 chips that are considered small in todays standards so I do not have any problems collimating either of my scopes.

Again just my opinion, and worth that you paid

Dean
Hi, Dean.

I guess that the one from Orion UK that you are referring to is the following:

http://www.teleskop-...-corrector.html

I'm not an expert but to my mind it seems to be a high-end telescope.

larterpchaka

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Re: Newtonian vs RC?
« Reply #11 on: January 31, 2018, 03:01:01 AM »
Yes it is however some upgrades could make it better. Depending on your imaging train, it could really use an additional set of rings to mount the focuser too. Look up Strong Man Mike astroimaging at his AG12. He seems very happy with it. Look at the pics of mine on the astromiager site, the focuser mounts to the rings for absolutely no flex what so every. Mikes is that way too. That is very important on faster scopes.

The new AstroTech truss tube newt looks promising for a lower end scope, but they have some flex issues that are being worked out. Still a very neat concept.

If your looking for longer focal lengths, like 1500mm+ then the RC or iDK would be a good way to go, shorter wider the newts are great. Look up Steve Cooper on astrobin. He has a 16" RC in Florida and is getting great results. He recently joined Deep Sky West observatory and said when comparing their 12" RCOS to his, he is very happy with that AT. And when you consider the cost difference.

I would have liked to get the AGO 10" iDK as it is F/6.7 native and corrected. But at the time Dave did not want to make just 1 as he did not have any other orders for them. Plus the fact they are really not much less cost than the 12" anyways. Of course he made a run of them sometime after I got mine, figures.  But again for the money the AT is good, after I put on the 3" Feathertouch and posidrive. Difference in the higher end RC scopes is mechanics are much better, and of course mirrors are usually better too. This is with both RC and newts.

Watch astromart as astrographs come up often. There was a 10" AGO newt the other day. As for my 12", I doubt I will ever sell it as longs as I have an observatory to keep it permanent. And my trusty little Tak Epsilon 160 is a keeper for life.

Dean

Andre Ransom

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Re: Newtonian vs RC?
« Reply #12 on: January 31, 2018, 01:26:07 PM »
Quote
Quote
Quote
RCs are chosen by some rather than large Newts because they're more compact.  Among other things that's easier on the mount, sheer length and bulk matters.  They can be hard to collimate.  There's a difference between the low end RCs and the expensive premium ones in this regard.  The very precise high quality mechanical components of the premium versions make a large difference.  But any RC will be harder to collimate than a Newtonian or SCT.
Another advantage of the RC for imaging is generally longer backfocus, for things like off axis guiders and filter wheels.
Visual and AP of DSOs are completely different because of the "sensors".   Your short exposure eyes need a lot of aperture to gather light really fast, but are forgiving of errors like tracking and aberrations.  .005mm pixels gathering light for some time are extremely unforgiving.  Most people who do both have different scopes for each.  Generally RCs  are used for imaging, Newtonians for visual.
Planetary is more like visual (short exposures), imaging DSOs is a unique thing.  Long exposures change everything.
RCs have a large central obstruction which reduces contrast.  An issue for visual, easily dealt with in processing for imaging DSOs.  If you want to image with a Newt, you'll need a coma corrector.  With an RC a field flattener can be useful.
This is not a question of which is technically "better".  More a matter of personal needs and personal taste.
I was looking at the Astro-Tech Truss Tube 14" RC for about $5,800... not sure if that one is considered high quality or low-end... as you can get some RC's for $400 and others for $25,000... it seems to sit (price-wise) kind of in the middle?  Although a little on the lower-side... It's hard to find any reviews so I appreciate your comments.  If it is considered a not very well made one, I'd rather buy a well-made Newtonian than a cheaply made RC...
I think the new version of the AstroTech truss RC scopes are good for the money, however a DK from Planewave or iDK from AGO would be considered top of the line.
As for newts, the TS is not what I would consider near top of the line.  The ASA is considered to be up there, along with the UK orion optics AG scopes.   My AGO newt was the first production 12.5" that he made, and it turned out to be more difficult that he thought.  Ended up learning a lot, we both did, after the first one had some issues.  He ended up making me a completely new scope with improvements he thought was needed.  The new scope is absolutely great, but cost him much more to make.  He only sold about 4 of the 12" and maybe 4 of the 10" I think and had removed them from his standard product line up as they are expensive to make, and a limited market.  And tricky to collimate for large chips, just like most astrographs really.  I use 8300 chips that are considered small in todays standards so I do not have any problems collimating either of my scopes.
Again just my opinion, and worth that you paid
Dean

Just a note the TS ONTC / ASA / Orion UK are essential the same scopes.
Tube - same in all three
Corrector - ASA 3" and TS 3" wynne are the same, Orion has an extra element
Mirror - ASA and Orion use Orion mirrors, TS uses Orion or local mirrors
Secondary - all three are different but TS does sell the ASA spider as an upgrade
Mirror cell - ASA uses a different one, Orion and TS are virtually identical except for the knobs
The TS UNC is a step down from the ONTC

Brandon Garrido

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Re: Newtonian vs RC?
« Reply #13 on: February 02, 2018, 07:22:41 PM »
Quote
Quote

Just a note the TS ONTC / ASA / Orion UK are essential the same scopes.
Tube - same in all three
Corrector - ASA 3" and TS 3" wynne are the same, Orion has an extra element
Mirror - ASA and Orion use Orion mirrors, TS uses Orion or local mirrors
Secondary - all three are different but TS does sell the ASA spider as an upgrade
Mirror cell - ASA uses a different one, Orion and TS are virtually identical except for the knobs
The TS UNC is a step down from the ONTC
I was not aware of that.  Sounds like it could be a decent scope then if you set it up with the right options.

Good we have so many choices out there today.

Dean