Keep RC 8 or sell and purchase a Skywatcher Quattro?? - Forums

Topic starter

Sep 15, 2023

Hello

I`m contemplating selling my RC8 in order to buy a fast newt something like a Quattro 8 or 10. I love the image scale of the RC8 and guiding doesn`t seem to be an issue with my OAG on my EQ6R Pro.

Just wondered what you guys and ladies think?

CS
Alan

andrea tasselli

Frequent contributor

Sep 15, 2023

Go for it but get a 10".

patrice_so

Sep 15, 2023

If guiding is sufficient and if you are not afraid of collimation, that leaves you with the following question : how good is you sky ?

Where I leave, the seing is not good enough to justify using a RC scope. The end image of a galaxy is not better with the RC at 1600mm with f8 than it is at 800 with f4. The latter is much faster though.

Aris Pope

Sep 15, 2023

I love my 10" Newtonian. if you get the 8' or 10" make sure to get the Starizona Nexus 0.75x Coma Corrector. It will bring the Quattro's down to f/3. My 10" Orion is 900mm focal length at f/3.5 and my 6" GSO Imaging Newtonian is 458mm focal length at f/3. The Nexus is amazing at correcting coma and making the scope faster at the same time.

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Andy 01

IOTD Staff

Sep 16, 2023

I had an RC8 & hated it, too difficult to collimate and really, really slow.
Sold it and got a 10" f4 CF newt and it was a real game-changer - a far superior instrument!

Sean Mc

Sep 16, 2023

Why can’t someone make a scope that weighs 10lbs, is 1500mm fl, f4, doesn’t have diffraction spikes, and costs under $500???

honestly though, i’ve been debating rc and newt as well. I want what i listed above, but I have to compromise on something(s). Rc gets the reach covered, but is slow. Newt is fast but doesn’t have the reach.

maybe one of each?

¯\_(ツ)_/¯

Engaging

Drew Evans

Sep 16, 2023

Neither. Grab an SCA260. Total game changer for me.

Dave Bloomsness

Sep 16, 2023

I have the 10" Quatro which works good now, but I had to replace the tube rings, the dovetail bars (with wider ones), the spider and secondary holder and mirror and the focuser. I probably could have used the stock focuser and just replaced the top ring that holds the camera / eyepiece. I also had to have the mirror re-figured as the original one had a turned edge and a central depression. So the total cost was more than 3 times the original cost. But now it works great at f4 and f3 with the Starizona Nexus.
I also have the GSO 10" truss tube RC. The RC has great image scale for smaller DSOs, but my skies aren't steady enough so I usually use the AP reducer to bring it down to f6, which is definitely a compromise. If I had to sell one, it would be the RC.
So the real question is what are you mainly imaging and how steady are your skies? They're both good scopes, but the Quatro will reduce tour exposure times quite a bit, even when imaging with narrow band filters.

I hope that helps.
Dave

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Christian Großmann

Sep 17, 2023

Hi Alan,

I own a RC8, an 8" f/4 and a 10" f/5 Newton. The RC8 is my least favorite and I thought several times about selling it. I really prefer the Newtons. You may be able to collect about 4 times the light as with the RC. This is a huge difference especially for narrowband images. There are several downsides to the Newts as well. Especially balancing is a bit difficult if you use a heavy camera setup. I had some trouble with the focusers, so I wouldn't buy the cheapest versions.

The 10" f/5 is a bit too heavy for the EQ6 mount, in my opinion. I don't know about the f/4. It should be lighter, but both are not worlds apart. So personally I'd go for the 8". If you need the focal length, then go for the 10". It is indeed the better choice if your mount can handle it.

I do regret buying my RC8. It seems to be a good choice back then. But it feels like the images were somehow different than those of all my other scopes. I can't explain it. But I'm sure I'm right.

This is just my opinion, but it seems to fit the suggestions above.

CS

Christian

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MarcoPalaferri

Sep 17, 2023

Hello, I understand that using the RC8 can sometimes be frustrating and unsatisfying. I had some doubts myself, but as you can see from my profile, I eventually figured things out and I'm now satisfied with my RC8 adventure. Furthermore, with good collimation, you can achieve excellent results. There are also reducers available that allow you to make the optics faster. I chose this route instead of buying another OTA because sometimes I want to use the full focal length of 1600mm. Good luck!

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SemiPro

IOTD Staff

Sep 17, 2023

If you keep the RC8, I believe that a reducer is a must. You are not doing yourself any favours by shooting at F/8. The Quattro 10 might be a little too much for the EQ6R to handle. Not only is it pushing the weight requirement, but its 1 meter long so it will struggle in the wind without a really sturdy mount.

So at the end of the day, you just need to decide what focal length suits you better between the RC8 and an 8" newtonian.

If you keep the RC8, here is some collimation information:

https://www.skydude.me/at8rccoll.html
https://www.ancientphotonsastro.com/post/bench-collimating-a-gso-rc8

What people tend to leave out is how critical the spacing between the primary and secondary are. When you buy it from the factory its should be properly set, but it is possible to throw it out by tweaking stuff at home. A ronchi eyepiece can tell you if your mirrors are properly spaced or not.

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Marius Bednar

Sep 24, 2023 · Edited: Sep 24, 2023

I recently did that move away from the 6" RC to a Sky-Watcher 6" quattro. I always used my RC with the .67 reducer because I felt anything higher than the 0.85"/px image scale was more than my average, less than ideal sky conditions (living right in the middle if a major city) supported. I was quite happy with the RC's frame size @ 924 mm, adequate for galaxies but large enough for many nebulae.
At some point however I wanted to try imaging at a lower imaging scale, expecting only little sacrifice in details (@ 1.5"/px and average seeing of 3") but a clear improvement in imaging speed / SNR.
Well, I do not regret my decision. Also I can achieve better collimation with the newtonian. You may want to have a look at my gallery.

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Alan Hancox

Topic starter

Sep 24, 2023

Hello Marius

Well I've made a decision. I'm keeping the RC8. I love the image scale and 0.61 arc secs / pixel is readily available and achievable at my location with a few tweaks of the PHD2 settings. Usually aggression settings and exposure. I do want something faster and more widefileld so I'm looking for a 130 or 150 PDS.
Great images!

Marius Bednar

Sep 24, 2023 · Edited: Sep 24, 2023

Alan Hancox:
I do want something faster and more widefileld so I'm looking for a 130 or 150 PDS.

Keeping the 8" RC and getting something with shorter FL and faster focal ratio in addition is of course even better 😀.

The compact form factor of the RC is the other thing I liked. The step from the 6" RC to the 6" f/4 newtonian even required me to add another weight. (This is however specific to the short 5" or 6" as you can't rotate the tube so that the camera points down, as it will not clear the mount; unless you slide the tube upwards but then you will be unbalanced in dec). The bigger / longer FL newtonians will get very bulky fast...

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Tommy Lease

Sep 24, 2023

If your mount can support it, get the 10" f4 newt. Speed + aperture creates some awesome images!

Tommy