G'day Robin. Filters are 13nm Astronomics. Can't post images today, will tomorrow. Not the stars bloated per se, more like a halo around them. Seem to recall Greg Bradley(?) talking about it once as though common. Maybe I was mistaken or misunderstood. But my OIII subs do have this halo.
I don't see this Troy. One tip, don't shoot O3 under a bright moon. You can mostly get away with S2 and Ha but try and time the O3 for when the moon isn't in the sky for a better result.
Thanks for the link, Peter. Interesting. Checked my Ha filter and no halo, but the OIII and Hb do show similar halos to that second link. Scope is only f/7.5.
Robin - no moon around when I used the OIII this time, but good tip for future. Thanks.
G'day Robin. Filters are 13nm Astronomics. Can't post images today, will tomorrow. Not the stars bloated per se, more like a halo around them. Seem to recall Greg Bradley(?) talking about it once as though common. Maybe I was mistaken or misunderstood. But my OIII subs do have this halo.
Is this the kind of thing you're describing as a halo?
This is a cut from an O3 stack.
Peter
If that is it, then it is the trademark Astromoniks effect (older filters only).
Try an additional IR cut filter if you don't want to return the filters for replacement.
As a matter of interest and, perhaps, comparison, the filter that produced the halo in the image a loaded yesterday was a Baader. Tonight, I swapped it out for one of those Orange Bright brand OIII filters and the same star did not produce any visible halo.
Peter
I'd be really interested to know if an additional IR cut filter would remove the effect on the Baader if you ever get a chance.
I do have a Baader UV/IR cut filter but they won't fit in the filter wheel if they're 'stacked' so it will have to wait until the opportunity arises. But like you, I would be interested to see the results.
Peter
Managed to sneak some test shots on Sirius in between the clouds tonight. These are stretched a lot to highlight the halos. Some pretty weird patterns in there. 5x1m subs each. Left to right is Ha, Hb, L, OIII, SII.
Anyone able to help diagnose them? I do see the Astronomics filter issue that Poita linked above at least in some of the shots. Imaging train was 10" Newt, MPCC, all Astronomics filters, and QSI583ws.
On a side note, how does the collimation and field flatness look to you? Any signs of issues there?
Sent off those images and the other details Astronomik asked for last weekend. Heard back from them on Friday. They're doing an analysis of my images next week. They told me that in their preliminary look, there was some halos from the filters but also some reflections from the MPCC.
Bit puzzled about the MPCC comment since they don't show up in the Luminance image, which was also shot through the MPCC.
I heard back from them last night. They're saying there's 2 different reflections/halos in there. The tight inner ones around Sirius are caused by the filters, the larger reflections (with the spider vanes showing) are caused by the MPCC. Kinda what we already knew, but the good news is that they're sending me out a replacement set of "no-halo" filters!
Must thank you guys again for your links and help.