here a comparison!
I imaged in January 2017 NGC 281 without filter, at cold temperatures, with a Canon T3i; 26x6 min at ISO 200...
...and now in September 2019 with my "special Duo-filter": that's an Astronomik UHC-Clip-filter and a 2" Idas V4-filter, together in the image train.
So I have 30nm Green/Blue and 16 nm Red; taken with a Canon T7i, 17x10 min at ISO 800 and warm temperatures (16°C; many hotpixels).
Telescope was every time the TS APO 80/480 at f/4.8.
Here a similar field of view for comparison; what is what, will be clear quickly.
By the way, all pictures, as ever, guided with a 500mm guide tube and manual guiding with a double cross eyepiece. So I'm the guider.
If I look at the image below, with the smaller stars, ca. 2"/Pixel, I ask myself, is this a sensefull border in resolution for my polluted place, to use this combination the most time...
I believe, in the image below, the Pac-Man has eaten up completely.
Edited by hobbyknipser, 22 September 2019 - 01:10 PM.