Dust on flats & ZWO EFW - Filterwheel not stopping in exactly the same spot?

domsel

Hello everybody & Team ZWO,

I'm having lots of trouble last few months trying to figure out why my flats are no longer working properly. I've got an Esprit 120ED with flattener hooked up to a 36mm ZWO EFW and ASI1600mm Pro (among lots of other ZWO hardware). If you look at the attached final calibrated and registered master (Luminance) image, the dust "crater" is still visible. Based on the size of the spot, I've identified the "moving" dust to be on the filter and have further narrowed it down to the filterwheel not stopping exactly at the right spot when shifting between filters. I'm also running an ASIAir, so I enabled "rotate filters in one direction", but that doesn't seem to solve the problem. The problem is most obvious with the Luminance filter, but that's because it's luminance, the other filters have the same challenge. I've also recalibrated the EFW, but no luck there either. Please advise what else I can try or if it's something completely different that's causing this behavior.

Thanks,

Matt

PMTeam@ZWO

domsel The filters is installed on one side, it will cause the problem of imbalance. This imbalance will cause the rotation not to the correct position. If the filter wheel cannot be rotated to the correct position, an error code will be displayed on ASIair. You can provide the error code.