How to handle 'bloaty' filter on bright stars?

3 replies90 views
John Stone avatar
I have an Esprit 100ED, an ASI2600mm Pro with Antlia Dark LRGB filters.

The problem I'm having is that on bright stars I'm getting uneven star "bloat" so what happens that I get really funky colors on those large star halos after SPCC.

I've triple checked the focus offset between the L,R,G,B filters (NINA Filter Offset Calculator 10x iterations). And I've confirmed the offsets with manual focus runs close in time to each other, but still I get uneven halos.

For example

Red:


Green:


Blue:



That fat blue halo is causing this star's halo's color to be completely wrong.

Any ideas?
Well Written Engaging
andrea tasselli avatar
Get a B filter with a cut-off above 420nm.
John Stone avatar


Looks to be about 390nm or 395nm FWHM.  Do you really think the 30nm difference will make a difference?
andrea tasselli avatar
Yes