Uploaded August 2026 | Updated September 2026, 3 hours ago
Ever look at your stars and think, "why don't these look like circles?" In this video, I break down the most common telescope aberrations — what causes them, how to tell them apart, and how to actually fix them (or figure out when you can't).
Kstars Aberration Inspector Tutorial: youtube.com/watch?v=IbbxJJS9W48&t=380s @johneevans1
0:00 – Intro: What's actually wrong with these stars?
0:40 – Welcome / My Sharpstar 130
1:13 – Definitions (on-axis, off-axis, image circle, diffraction)
2:44 – Why stars aren't round (the eye analogy)
4:07 – Spherical Aberration
7:02 – Field Curvature
9:48 – Coma
11:45 – Astigmatism
13:21 – Pinched Optics
13:59 – Honorable Mentions: Miscollimation, Tilt, Chromatic Aberration
15:14 – Three Kinds of Problems (Optical vs. Mechanical vs. Seeing)
16:09 – Why Combined Aberrations Are So Hard to Diagnose
17:01 – How to Actually Fix It (Order Matters)
22:02 – Newtonian Reflectors
22:23 – Schmidt-Cassegrains (SCT)
22:58 – Classical Cassegrains
23:11 – Ritchey-Chrétien (RC)
23:32 – Maksutov-Cassegrain
23:49 – Dall-Kirkham
24:05 – Refractors (Doublets/Triplets/Quadruplets)
24:37 – Outro and Thank You
Become a buymeacoffee member to help choose which products I review: buymeacoffee.com/deepskydetail
Affiliate Links:
High Point Scientific: highpointscientific.com/?rfsn=8751569.cc9d94
Agena Astro: agenaastro.com/?rfsn=7802039.3f4caf
Skywatcher HEQ5 Mount amzn.to/3NVrVQi
Skywatcher 80mm F7.5 Doublet amzn.to/47mbfZi
ZWO EFW mini filter wheel amzn.to/48OxhoN
Optolong LRGB Filter Set (1.25") amzn.to/47r23Tw
Orion 0.8x Reducer amzn.to/47s64a4
USB RJ45 Cable for Controlling Mount amzn.to/4aPlIzu
Raspberry Pi to control mount amzn.to/48mTBWH
R Pi case with touch screen amzn.to/3HvdNKl
ZWO Autofocuser amzn.to/3Skg0hX
ZWO 294MM Pro Camera: bit.ly/3tZmjOo
HEQ5 Mount: bit.ly/3O7VQVz (mine is Orion Sirius, which is equivalent)
ZWO Filter Wheel: bit.ly/3Soo5lw
Optolong Filters (LRGB, SII, Ha, OIII): bit.ly/3SlEPtJ (the Ha and OIII narrowband filters are better than what I have)
Skywatcher Evostar 80mm: bit.ly/4bfVjev (equivalent lens)
USB RJ45 Cable: bit.ly/48FRj50 (connects mount to laptop directly; mine is a different brand, but this should do)
ZWO Autofocuser: bit.ly/425XUDB
0.8x Reducer: bit.ly/3tQlbg7 (mine is Orion, but this should be equivalent)
Join this channel to get access to perks:
youtube.com/channel/UCoI4bUAKNI3rdvesiNqtYJw/join
Ever look at your stars and think, "why don't these look like circles?" In this video, I break down the most common telescope aberrations — what causes them, how to tell them apart, and how to actually fix them (or figure out when you can't).
Kstars Aberration Inspector Tutorial: youtube.com/watch?v=IbbxJJS9W48&t=380s @johneevans1
0:00 – Intro: What's actually wrong with these stars?
0:40 – Welcome / My Sharpstar 130
1:13 – Definitions (on-axis, off-axis, image circle, diffraction)
2:44 – Why stars aren't round (the eye analogy)
4:07 – Spherical Aberration
7:02 – Field Curvature
9:48 – Coma
11:45 – Astigmatism
13:21 – Pinched Optics
13:59 – Honorable Mentions: Miscollimation, Tilt, Chromatic Aberration
15:14 – Three Kinds of Problems (Optical vs. Mechanical vs. Seeing)
16:09 – Why Combined Aberrations Are So Hard to Diagnose
17:01 – How to Actually Fix It (Order Matters)
22:02 – Newtonian Reflectors
22:23 – Schmidt-Cassegrains (SCT)
22:58 – Classical Cassegrains
23:11 – Ritchey-Chrétien (RC)
23:32 – Maksutov-Cassegrain
23:49 – Dall-Kirkham
24:05 – Refractors (Doublets/Triplets/Quadruplets)
24:37 – Outro and Thank You
Become a buymeacoffee member to help choose which products I review: buymeacoffee.com/deepskydetail
Affiliate Links:
High Point Scientific: highpointscientific.com/?rfsn=8751569.cc9d94
Agena Astro: agenaastro.com/?rfsn=7802039.3f4caf
Skywatcher HEQ5 Mount amzn.to/3NVrVQi
Skywatcher 80mm F7.5 Doublet amzn.to/47mbfZi
ZWO EFW mini filter wheel amzn.to/48OxhoN
Optolong LRGB Filter Set (1.25") amzn.to/47r23Tw
Orion 0.8x Reducer amzn.to/47s64a4
USB RJ45 Cable for Controlling Mount amzn.to/4aPlIzu
Raspberry Pi to control mount amzn.to/48mTBWH
R Pi case with touch screen amzn.to/3HvdNKl
ZWO Autofocuser amzn.to/3Skg0hX
ZWO 294MM Pro Camera: bit.ly/3tZmjOo
HEQ5 Mount: bit.ly/3O7VQVz (mine is Orion Sirius, which is equivalent)
ZWO Filter Wheel: bit.ly/3Soo5lw
Optolong Filters (LRGB, SII, Ha, OIII): bit.ly/3SlEPtJ (the Ha and OIII narrowband filters are better than what I have)
Skywatcher Evostar 80mm: bit.ly/4bfVjev (equivalent lens)
USB RJ45 Cable: bit.ly/48FRj50 (connects mount to laptop directly; mine is a different brand, but this should do)
ZWO Autofocuser: bit.ly/425XUDB
0.8x Reducer: bit.ly/3tQlbg7 (mine is Orion, but this should be equivalent)
Join this channel to get access to perks:
youtube.com/channel/UCoI4bUAKNI3rdvesiNqtYJw/join
