I surely needed to get out last night and I had a great time trying out my new Stellarview field flattened/0.80 focal reducer. I anticipated some issues with plate solving and/or focus and had none.
Guiding was good at an average 1.1 arcsec total rms error in PHD2 (good for me).
Shot 240 second lights with my
Ha modded D5300 at iso 400 with an IDAS LPD-D1 filter (about three hours total integration).
I am happy with the image. Definitely pleasant enough and possibly on the bluish side, but a big improvement over my first time imaging M13.
There are some things with the image I would like to improve on next time and hopefully some of you experienced imagers might be able to help with some suggestions.
First off, I somewhat blew out the core. Apparently, 240 seconds at iso 400 is too much exposure. The histogram peaks in
APT were in the first and second sectors from the left which are below recommendations in the
APT manual. Perhaps 120 second lights?
The other thing is that some of the stars in the corners are slightly non- homogeneous in color. I did check the camera and there is a significant amount of flexure at the t-ring possibly causing the camera sensor not being perfectly perpendicular to the imaging train. Possibly a contributor to the corner star color?
I will tell you though, that this is the flattest image that this rig has ever produced by far! I feel like the
FF is doing a great job. When I compared these light frames to light frames in other sessions (with no
FF/
FR), the corner stars are beautifully round and don’t look like flaring comets as before!
If you have any suggestions please comment and thanks for looking!
Jim
Scopes: Explore Scientific ED102 APO, Sharpstar 61 EDPH II APO, Samyang 135 F2 (still on the Nikon).
Mount: Skywatcher HEQ5 Pro with Rowan Belt Mod
Stuff: ASI EAF Focus Motor (x2), ZWO OAG, ZWO 30 mm Guide Scope, ASI 220mm min, ASI 120mm mini, Stellarview 0.8 FR/FF, Sharpstar 0.8 FR/FF, Mele Overloock 3C.
Camera/Filters/Software: ASI 533 mc pro, ASI 120mm mini, ASI 220mm mini , IDAS LPS D-1, Optolong L-Enhance, ZWO UV/IR Cut,
N.I.N.A., Green Swamp Server, PHD2, Adobe Photoshop CC, Pixinsight.
Dog and best bud: Jack
Sky: Bortle 6-7
My Astrobin:
https://www.astrobin.com/users/Juno16/