Newt to complement 80mm APO?

I won’t get into the weeds of this or that scope but to address your basic problem, yes, keeping the focal length the same but decreasing the focal ratio by increasing the aperture is a great solution.

Erlend Langsrud:
I can only say what I would do. I would get a 6” F/5 newt to get a bit more range and in case I wanted to do some planetary in the future.

I don’t think av 6” F/4 newt will complement your refractor. It will replace it. You will find you get so much more signal once you overcome the hassle with collimation, straylight etc.

Chris White- Overcast Observatory:
If you plan on using a small sensor like that, you could even get into something really fast, like the f2.8 Newts. I think sharp star makes a 6” f2.8. It will have a shorter focal length than your refractor, but will really drink up photons in your limiting skies (at the expense of being a little undersampled of course). With a smaller chip you dont need a huge corrected field, and while collimation is magnitudes more sensitive with a faster scope, its a skill that you will need to learn and be able to succeed at whether f4 or f2.8. I havent used this scope, butit might pair well with your 533.

nadz11.ns · Oct 23, 2025, 09:20 AM

I currently image with a TS Optics 80mm APO (544mm, f/6.8) on a SkyWatcher Wave 150i, with a Touptek 533 and filter wheel. 

The image quality is great, but under Bortle 7–8 skies here in Ireland, the limited number of clear nights means f/6.8 forces me into long integration times to get the results I want.

I am considering adding a faster Newtonian mainly for calm nights, while keeping the APO for windier nights and for convenience. The options I am looking at are:

• SkyWatcher Quattro 150P – fast system and comes with a coma corrector. Shorter tube than the PDS and similar focal length to my APO.

• SkyWatcher 150PDS – f/5 and longer focal length, but would need to buy a coma corrector separately. Tube is longer than the Quattro.

My thought process:
The 150P gives me a similar focal length to my APO, but with a faster f-ratio and more aperture, so I can better exploit the rare clear nights. However, I’m unsure whether it makes sense to buy a second scope with almost the same focal length.

If you were in my situation, would you add a fast Newt at a similar FL for speed, or would you choose a different focal range instead? I’d like to keep the telescope + accessories under €1k if possible, but I’m open to practical suggestions based on real experience. Happy with the FOV at this FL. 

I also know the SW Newts often benefit from upgrades like a better secondary spider, primary mask, and focuser.

One question here: with a solid spider, will collimation generally hold when moving the tube in and out of the house? Minor tweaks are fine, but I don’t want major collimation work every session.

8” f4 if your budget will allow. Gets you 800mm a nice jump from 80mm at 544mm. Otherwise a Carbonstar 150 f4 at 600mm. Faster more light gathering but essentially the same reach.

CS, Bob

andrea tasselli · Oct 26, 2025, 09:33 PM

Expensive and pointless, for a small sensor. At most get the Nexus 0.75x CC.

Rubbish… In B7/8 skies, an f2.8 newt would be great, regardless of sensor. And it could correct up to APS-C for the next camera. They claim full frame correction, but I think thats just probably marketing gibberish.

nadz11.ns · Oct 23, 2025, 09:20 AM

I currently image with a TS Optics 80mm APO (544mm, f/6.8) on a SkyWatcher Wave 150i, with a Touptek 533 and filter wheel. 

The image quality is great, but under Bortle 7–8 skies here in Ireland, the limited number of clear nights means f/6.8 forces me into long integration times to get the results I want.

I am considering adding a faster Newtonian mainly for calm nights, while keeping the APO for windier nights and for convenience. The options I am looking at are:

• SkyWatcher Quattro 150P – fast system and comes with a coma corrector. Shorter tube than the PDS and similar focal length to my APO.

• SkyWatcher 150PDS – f/5 and longer focal length, but would need to buy a coma corrector separately. Tube is longer than the Quattro.

My thought process:
The 150P gives me a similar focal length to my APO, but with a faster f-ratio and more aperture, so I can better exploit the rare clear nights. However, I’m unsure whether it makes sense to buy a second scope with almost the same focal length.

If you were in my situation, would you add a fast Newt at a similar FL for speed, or would you choose a different focal range instead? I’d like to keep the telescope + accessories under €1k if possible, but I’m open to practical suggestions based on real experience. Happy with the FOV at this FL. 

I also know the SW Newts often benefit from upgrades like a better secondary spider, primary mask, and focuser.

One question here: with a solid spider, will collimation generally hold when moving the tube in and out of the house? Minor tweaks are fine, but I don’t want major collimation work every session.

8” f4 if your budget will allow. Gets you 800mm a nice jump from 80mm at 544mm. Otherwise a Carbonstar 150 f4 at 600mm. Faster more light gathering but essentially the same reach.

CS, Bob

Jordan Morley:
Try to get anything used under 8” and just mess around with it cos whichever one you get its going to need tinkering and that’s the best part of having a newt (: