6 inch imaging Newtonian choices?

First off, a GTi would NOT handle a 6” f/4 newt, if that is what you have. GSO optics are OK with few lemons here and there. Be prepared for some TLC to get a performer notably with the primary cell being quite flaky and frankly I would shy away from a monorail, too many issues with tensioning in variable temperatures. Go for a R&P focuser. My choice would be either a high performance high quality newt such as the Alpha or this one for a smaller budget: StellaLyra 6" f/4 M-LRN-D Carbon Fibre Imaging Newtonian Reflector with 2" Dual-Speed R&P Focuser | First Light Optics

Yes, it would be a problem especially with an EAF. Carbon tube brings you lower thermal expansion (not that you really need it with a short 6” but good to have nonetheless) and much higher stiffness with the same weight. I don’t have one yet but I’m gunning for the 8” instead.

This is the equivalent of the StellaLyra, in the EU (Italy). I now the guy and I can recommend them: Astrografo Newton 150/600 Tecnosky CARBON Series

I have a GSO 6” F/6 newt with the Crayford focuser. I also have a mono 585. I went with the F/6 because paired with the 585, you can very much live without a coma corrector. That simplifies things somewhat with no worries about back focus. On the focuser, I could certainly benefit from something more capable but the Crayford works. My EAF is attached to the tube so that can be made to work as well with a bit ingenuity.

Mine might be a fluke but the primary is excellent. It’s better than 1/10th wave on the bench. I use the OTA at both the native F/6 and also in conjunction with a 2” ED Barlow which gets me out to 1580mm F/10.4. The only modification I’ve made is a 3d printed mirror mask to clean up the diffraction around brighter stars. Lastly, I’ve not had any problems or difficulty in collimation. You certainly don’t need any special tools or cameras to do it. I carry the scope in and out to the backyard for sessions and I haven’t had to touch the collimation knobs for over a year now.

Mine might be a one-off fluke but I’m getting a lot of performance for very little money spent and few modifications made.

Apertura CarbonStar.

CS, Bob

Yes it is. A big part of this process is to look at each feature and ask yourself:

Will this make a visible difference in my images?

Will this feature make my images easier to aquire?

Is this feature more hype than substance, then loop back to question #1

Eren · Apr 20, 2026, 10:34 AM

Thank you all for your responses.

I’m trying to consider the cheapest options right now, what about the GSO 6 F/4 Carbon R&P Newton? EAF compatible R&P Focuser and looks pretty good to me..

If not I would probably go with the cheaper Monorail version and upgrade everything on the way since the price difference between the scopes of GSO and other suggestions is immense 😅

Yes it is. A big part of this process is to look at each “feature” and ask yourself:

Will this make a visible difference in my images?

Will this feature make my images easier to aquire?

Is this feature more hype than substance, then loop back to question #1

I own a 6” carbon fiber Newtonian from Teleskop Service. I don’t know what the experience of others has been, but I’ve used it without an electronic focuser in CA, TX, and FL, and with the relatively modest overnight temperature changes seen most nights in these states (15 degrees F or less), I’ve never seen any significant change in FWHM over the course of an overnight session.

My Newt also has a quartz primary, I don’t know how much of a difference that makes. It’s also possible that some degree of focus loss is being hidden by the fact that with a standard astro camera, I’m a bit undersampled at 600mm focal length and so digital resolution is limiting anyway.

If you go with a carbon OTA, it might be worth testing to see how much value the EAF adds if you are budget-limited.

I use EAFs on all my other scopes precisely because I see FWHM creeping up all night if I don’t.

Tony Gondola · Apr 20, 2026, 02:08 PM

Yes it is. A big part of this process is to look at each feature and ask yourself:

Will this make a visible difference in my images?

Will this feature make my images easier to aquire?

Is this feature more hype than substance, then loop back to question #1

Eren · Apr 20, 2026, 10:34 AM

Thank you all for your responses.

I’m trying to consider the cheapest options right now, what about the GSO 6 F/4 Carbon R&P Newton? EAF compatible R&P Focuser and looks pretty good to me..

If not I would probably go with the cheaper Monorail version and upgrade everything on the way since the price difference between the scopes of GSO and other suggestions is immense 😅

Yes it is. A big part of this process is to look at each “feature” and ask yourself:

Will this make a visible difference in my images?

Will this feature make my images easier to aquire?

Is this feature more hype than substance, then loop back to question #1

Yes, I understand.. I will take my time with the decision..

Tom Boyd · Apr 20, 2026, 02:08 PM

It looks to me like the Apertura CarbonStar is just a GSO scope you mentioned above rebranded as Apertura. If so, I own the 8” version and love it.

I’ve seen a lot of positive reviews about the Carbonstar, so I’m happy that there is an alternative (or the original) in the EU.

Eren · Apr 22, 2026, 02:49 PM

Christian Andres · Apr 22, 2026, 01:38 PM

I am quite happy with my Skywatcher 150 PDS. It needs some tuning and modifications for sure but that is part of the hobby for me. If you are ok with starting a small project then I would say go for a GSO or Skywatcher steel tube newt. They offer a lot of value for a fair price and can be found quite cheap second hand. If you are looking for a scope that works perfectly out of the box, these newts are not the best choice tough.

I don’t mind doing modifications on my scope, or designing something specifically for one. I made some custom modifications to my ZS61II, but a reflector is just a new territory for me. My only issue is the focuser with e.g. the GSO which is a bit more expensive than just printing some parts or flocking.. That’s why the Carbon version looks very promising with the R&P focuser.

On thing worth noting is that, in general, Newtonians, due to the simplicity of the design are the easiest telescopes on the market to mod. You can really get into the guts of these things and make changes without worrying about ruining anything.

Tony Gondola · Apr 19, 2026, 09:00 PM

Lastly, I’ve not had any problems or difficulty in collimation. You certainly don’t need any special tools or cameras to do it. I carry the scope in and out to the backyard for sessions and I haven’t had to touch the collimation knobs for over a year now.

Mine might be a one-off fluke but I’m getting a lot of performance for very little money spent and few modifications made.

I don’t think this is a fluke to be honest.

And F/6 newtonian mirror is considerably easier to figure than an F/4, so the chances that an F/6 mirror is absolutely stunning quality vs the typical F/4 mirror is no surprise, and so many people believe that a newtonians are by design, optically inferior to a refractor, the fact is, a $250 6~8” F/5~F/6 newtonian that is well built, with a few minor ‘imaging specific’ tweaks like your mirror mask, and maybe some flocking or an improved focuser is an incredibly powerful imaging tool…

And absolutely, at F/6 with a 585 sensor, you wouldn’t need a coma corrector, and your collimation would be ROCK solid.

I had a skywatcher 8” F/6 for a number of years, and collimated it twice in that time… I have no doublt in my mind that a 6” F/6 newtonian with a good collimation would not absolutly remain stable for quite a long time.

I had the insane notion that the best telescope for me would be a 6” F/2.8 newtonian. And whilst the incredible signal to noise ratio the scope can put together in a short 2~4h is absolutely priceless, I have had to tweak it EVERY SINGLE TIME I use it, and prior to some modification, I had to get all my imaging done before or after the meridian, as the meridian flip could cause enough mirror movement to throw the collimation.

The thing EVERYONE should be aware of when looking at a newtoninan for imaging, is what the ‘acceptable’ margin of error in mechanical alignment is.

For a f/6 mirror, you have a sweet-spot radius of 1.08mm This sounds incredibly small, but you’re talking about “so long as the mirror’s are aligned within a 2.16mm zone, you’re good to go.

for an F/4 mirror, that sweet spot radius drops to 0.32mm.. Your optics need to be within 0.6mm of absolutely perfect alignment before the image degradation becomes noticable..

For the insane of us, who purchase an F/2.8 newt… We have a tolerance radius of 0.11mm…

An F/6 mirror can be perfectly collimated with a simple collimation cap, and remain within the tolerance for years. F/2.8 at the other end of the spectrum, requires a concenter eyepiece, a high quality barlowed laser, a cats-eye or autocollimator, in many cases, an electronic collimation camera, and a star test - used iteratively, and with the understanding that a 10° temperature change could cause the collimation to change with the telescope simply sitting on a shelf un-touched…

Part of me wishes I’d bought a 6” F/5 or 6… the other part watches the sky dim as all the photons funnel into my F/2.8 newt when I take the cap off the end… :D

Alex Nicholas · Apr 23, 2026, 04:00 AM

And absolutely, at F/6 with a 585 sensor, you wouldn’t need a coma corrector, and your collimation would be ROCK solid

Neither statements are true.