6" GSO Imaging Newtonian and the Starizona Nexus Coma Corrector brings it down to f/3

Ferenc Szabo:
I use 2 different ones. One is the Sharpstar .95X CC the other is the Starizona 0.75X
Despite the Starizona being the most expensive CC out there (unless someone knows another that cost more than $450)
I am not totally happy with the Starizona, while the Sharpstar being less than half the price doing very well.
Here are the reasons I am no longer a fan of the Nexus CC:
1. I can't get round stars with it. It's always showing elongated stars around the corners or flattened stars across the entire field.
I tried it on 3 different News, obviously can't be that all 3 newts have the same problem and magically repair themselves when I replace the CC with the Sharpstar CC.
2. Not enough threads to attach the camera and extensions. It's barely a few turns to tighten, I don't think it's a good design this way.
3. Expensive. It cost more than my Newts really, if I dont' count the modifications I've done to them.
4. Maybe it's meant to be used on 8" or larger, although I have an 8" Newt and the stars are still leave a lot to desire.
5. If you go to the website, it says "up to APS-C" sensor size. Well, I think the APS-C is stretching it. As I said I couldnt get nice stars with 4/3rd sensor and neither with the 533mc or the mm pro. I always have to crop and the 533 sensor isn't very big to begin with.
I'm ok with the Sharpstar CC, although I thought about getting another CC and see it in comparsion.

I’m new to the topic and fairly new to owning a Newtonian. Mine was built by @Dan Watt and is a Watt 8" ƒ4 Newtonian Astrograph. Currently I’m using a TS Optics 1x coma corrector and an Astor System laser collimator with barlow (takes me 1 minute to collimate). I have it on an AM5 with counterweight. I’m extremely pleased with this scope. 📷 IMG_0096.jpeg
I have several, depending on what I’m shooting. The main scope is the Skywatcher Quatro 300p 12” f4 coupled with the Skywatcher f4 coma corrector. For larger objects like Orion and Eta, I have the Skywatcher Quatro 200p 8” f4, also with the Skywatcher f4 coma corrector. I also have a Starizona Nexus 0.75x Newtonian Focal Reducer/Coma Corrector, which I have used on both scopes.
Andrew Murrell · Feb 27, 2026, 07:19 PM
I have several, depending on what I’m shooting. The main scope is the Skywatcher Quatro 300p 12” f4 coupled with the Skywatcher f4 coma corrector. For larger objects like Orion and Eta, I have the Skywatcher Quatro 200p 8” f4, also with the Skywatcher f4 coma corrector. I also have a Starizona Nexus 0.75x Newtonian Focal Reducer/Coma Corrector, which I have used on both scopes.
I have the exact same setup :)
Hello,
I have 2 DIY Newts that I use for astrophotography: an 8 inch F3.6 that has a Sharpstar 3 inch 0.85x coma corrector (producing F3 total), and a 20 inch F4 that has a 3 inch Teleview coma corrector (producing F4.5 total).
Both scopes have DIY sled focusers, carbon tubes, over size secondaries, and are both mounted on the same DIY single fork arm mount. Both scopes also have QHY600 cameras and imaging stacks with off-axis guiding and the 20 has SBIG adaptive optical guiding (and man was it tough getting the full stack into the Teleview back focus).
Dave
Paracorr type 2 and 10” skywatcher quattro. Iv got a nexus x0.75 but it requires so much fiddling I don’t use it. I like the paracorr as it suits my osc camera and produces nice coloured stars i’d like a 14” newt at some point in time just need more money 💰
I have a SW 250PDS 10” which I use for visual. I always said to myself I would not use it for astro; yup had to. Way too heavy for for SW AZEQ6 for astro but fine for visual. Had to do it though…Stuck my TV paracorr type 2 and ZWO 6200 in for some fun…lots of vignetting, and cannot get the paracorr in focus at the proper distance due to a different focuser. Use the Catseye for collimation, and some mirror flop to add to the confusion. Great fun walking downstairs for some astro…..Lots of light leaks looking at my darks but soon worked that out. Still happy with the old results. In PI now trying to process a recent photo.
I currently use a DIY 10” f/4.8 OTA with optics from Mirro-sphere (Franck Grière), a sandwich carbon tube, custom mechanics, and a 3” R&P focuser.
📷 scope.jpg
The corrector is a 2.5” Riccardi/Wynne model sold by TS. While I have yet to try large sensors, it provides very tight starts (down to 1.2” FWHM in good seeing conditions). I have also an 8” f/3.9 DIY OTA, but I don’t use it much these days. They share the focuser/corrector/imaging train assembly, I just need to unscrew the whole thing from one scope and screw it on the other one (M117 connection).
CS,
Dan
Here are some pictures of my 2-Newt setup
📷 Full_Setup.jpg
📷 8-Inch Sled Focuser.jpg
📷 20 Inch Diagonal.jpg
But Jordan, this is the only group I can show off to - everybody else thinks I’m bat-shit crazy (including my wife)!