I have not imaged over the summer but I decided to get my processing "eye" in with old data and try out some new software.
This a reprocess of M42 from February 2021. My scope was poorly collimated at the time hence poor stars and a focus gradient across the image.
(https://cdn.astrobin.com/thumbs/w5RQLe7Y4f81_16536x0_TveUidco.jpg)
The original data was overexposed and has some annoying streaks on the right side of the image.
Scope: Sharpstar 15028HNT on iOptron CEM 25P
ZWO ASI1600MM Pro at -15 (ZWO RGB filters)
Subs: L - 7seconds x 810 (yes, 810) R - 20 seconds x 115 G - 20 seconds x 150 B - 20 seconds x 180
Pixinsight:
BlurXTerminator
NoiseXTerminator
GraXpert
Pixinsight:
Masked Stretch
StarXTerminator
Curves Transform
This was my previous processing:
(https://cdn.astrobin.com/thumbs/GUb6EUVUHene_16536x0_Ap-UblQ8.jpg)
Not very subtle was it!
John
Much more subtle John, but what are those streaks, are they what you call focus gradient? Not heard of that before.
Carole
Hi Carole
Not sure what caused the streaks.
The focus gradient is the camera being off centred because of poor collimation and at a slight angle to the primary mirror. My telescope Is f2.8 which means the focal point has practically no leeway. The angle means that the image has zones inside focus at focus and outside focus - I called it a gradient to try to describe it.
Regards,
John