Nice captures ken, we've had quite a few good proms in the last week. that filament started as a nice prom a few days back with a lot of structure visible at high power through my LS100. What causes the newton rings, i've never encountered them with my asi174.
Gus,
Any time I use the ASI 174 with a barlow/ powermate the Newton rings appear...(not the case with the ASI 1600)
The only workable solution is to use the ZWO T2 tilter - guaranteed to work every time.
I was trialling an ES x3 extender which needs a 1.25" adaptor on the tilter - forgot!!
