Which would you choose 6” Newt or 4” Achro ?

[900SL]

Nice one Louis. I'm tempted by a used UNC 150mm f6 as an imaging scope for galaxies and lunar (will double my current focal length and give around 1"/px, or more with a barlow

I'm thinking it will be a noticable step up in resolution from my current 90mm f6, which is around 420mm fl with the reducer.

[Louis D]

3 hours ago, 900SL said:

Nice one Louis. I'm tempted by a used UNC 150mm f6 as an imaging scope for galaxies and lunar (will double my current focal length and give around 1"/px, or more with a barlow

I'm thinking it will be a noticable step up in resolution from my current 90mm f6, which is around 420mm fl with the reducer.

I am not familiar with that Newt, so I did a quick search and came across this thread on CN of someone using it for imaging.  It sounds decent, but the price is pretty steep for a 6" f/5 Newtonian with some issues that needed to be ironed out.  Hopefully, TS has resolved the issues the OP had in 2018.

[Louis D]

A bit off topic:

Seeing the recent thread on choosing a 4" refractor for visual (Choosing between 4" ED Refractors for visual), and having just compared my 90mm APO to my 150mm Newtonian, just exactly how much improvement would I see going up 10mm to 12mm in aperture to a 4" ED or APO refractor over the 90mm APO triplet?  Would that little extra bit of aperture reveal the Trapezium E component that the 90mm simply could not even hint at?  Should I instead jump to 120mm or 125mm for my next ED/APO?

[Ratlet]

7 minutes ago, Louis D said:

A bit off topic:

Seeing the recent thread on choosing a 4" refractor for visual (Choosing between 4" ED Refractors for visual), and having just compared my 90mm APO to my 150mm Newtonian, just exactly how much improvement would I see going up 10mm to 12mm in aperture to a 4" ED or APO refractor over the 90mm APO triplet?  Would that little extra bit of aperture reveal the Trapezium E component that the 90mm simply could not even hint at?  Should I instead jump to 120mm or 125mm for my next ED/APO?

I'd be quite interested in hearing people's opinions, even though I just got the 102/f7 what I really want is a Megrez 90 lol.  Strikes me as the perfect balance of correction, portability and quality.  The Megrez can be taken on an airline carryon without disassembly, whilst the 102 would require the focuser to be removed.

[900SL]

1 hour ago, Louis D said:

A bit off topic:

Seeing the recent thread on choosing a 4" refractor for visual (Choosing between 4" ED Refractors for visual), and having just compared my 90mm APO to my 150mm Newtonian, just exactly how much improvement would I see going up 10mm to 12mm in aperture to a 4" ED or APO refractor over the 90mm APO triplet?  Would that little extra bit of aperture reveal the Trapezium E component that the 90mm simply could not even hint at?  Should I instead jump to 120mm or 125mm for my next ED/APO?

I read somewhere that you should jump 30mm in aperture. So 120 -130 mm in aperture from 90mm, assuming mount can handle it 

Edited March 1 by 900SL