Anderl:
Ashraf AbuSara:
I don't know if anyone mentioned this here, but be prepared for diffraction spike galore with the Epsilon. Personally, I am not a fan of diffraction spikes, especially intrusive ones like the Epsilon has. Some of my star dense luminance shots of a milky way target with a star rich field can be dominated by diffraction spikes and bright halos around stars that are quite difficult to process.
Another thing to mention is if you plan on full frame imaging, I don't think the 180 supports it, but the FSQ will have no problem at all with a full frame sensor. The 160ED supports full frame, but takes some tinkering and the illumination drop off towards the corners is quite significant. I could never get perfect stars in the corners of my full frame sensor, but they are very useable.
Currently I have both the E160ED and the TOA-130 running remotely, and I enjoy my TOA a lot more. But that has more to do with personal preference. They all are excellent scopes.
Have you thought about „apodization“ as a solution against the star spikes?
most people say they don’t want to waste potential sharpness but that argument don’t makes a lot of sense to me. rc telescopes have a way bigger obstruction as an apodized newton type telescope and still nobody would say they aren’t sharp.
https://www.researchgate.net/publication/26475864_Apodization_of_the_flat_mirror_support_of_a_newton_telescope
That said, i would also go for the fsq
I think there's company that makes these little shapes that you can fit directly over your existing spider vanes, Cuiv has a video on it. It would be easy to 3d print a set if you have access to the technology. thing is, in any obstructed aperture you are going to have associated diffraction effects which will always result in a lowering of the final performance of the optical system, mainly you'll see it as visible effects like spikes and as a general loss of contrast resolution of course, stays the same. That's why an equal aperture refactor will almost always out perform a reflector. Same resolution but higher contrast Usually the best way to compensate is to go with a slightly larger aperture reflector.
If you do go with a reflector, you can have a say over how the extra diffraction from vanes effect your images. You can control the number of spikes by controlling the number of vanes. each vane creates 2 spikes 180 degrees apart. 4 vanes give you effectively 8 spikes (overlapping), 3 vanes would give you 6 spikes but the spikes would be fainter than in the 4 vane case. 2 vanes at 90 degrees from each other would give 4 spikes that are fainter than the 4 vane configuration. 1 vane would scatter the least light of all but having two spikes, 180 degrees opposite is a look not many could live with.
Another factor is the thickness of the vanes. Thick vanes give short, bright spikes. Thin vanes give longer but fainter spikes. you can eliminate visible spikes completely by using a curved spider which is the same thing those little masks do. The light still gets diffracted but it's evenly distributed around the star as sort of a faint haze. This reduces overall contrast but you'll have no issues with spikes. The other solution is to mount the secondary to a clear flat plate and the spike problem goes away. That's probably the best solution but I'm not aware of any makers of high quality Newtonians that offer it.
Bottom line is that if you really, really hate spikes, go with a refractor.. That said, spikes of any flavor can be minimized by not shooting excessively long subs and holding the stars back in post. Given everything that blurX can do, I would not be surprised to see spike elimination as a software tool in the future. In the bad old CCD days common software like CCD Calc could eliminate blooming spikes so eliminating vanes spikes really should be possible. In fact, I'm surprised no one has offered that yet.
