I'd love to see the advice from Optical engineers on the contrast issue,
I think alot of people are splitting hairs with the folded design and possible loss in contrast.
Most of us would never see the difference visually except maybe the most discerning visual observers.
If you are looking to be feet on ground with huge aperture, which seems to be a priority with OP, a folded design seems to fit the bill.
The folded design has the same central obstruction as an S.C.T design, less than most RC's...
Also for the light gathering issue, since loss in light gathering is measured by the square...Its a non issue...
Calculating rapidly a regular secondary vs a larger one for the folded and then comparaing to the primary's real estate...you are losing peanuts really on effective area.
I love my SCT's and don't really think about the central Obs when looking through them.
I dont see why that would change for a very large newton in order to make it accesible from the ground.
As for location, If I was constrained to a bortle 4 sky, then the only way left to get more signal in is more aperture anyway.
OP also said he could still move it later under even darker skies, which would get him the full potential of the instrument.
One last thing I'm seeing, the folded design would mean a smaller telescope footprint as well.
This could help to keep observatory costs under control. Don't know if it offsets it by much, should be looked into.
In anycase, this seems like an awesome project!
Edited by StellarField20, 25 January 2021 - 09:00 AM.