Complex of nebulae in the constellation Cygnus

 Posted: Oct 9th, 2024
Technical Info
Telescope/Lens: Samyang 135 mm. f/2 ED
Camera: Nikon D850
Mount: Ioptron SkyTracker
Software: PixInsight, Ps
Exposure:
83 x 120" ISO/Gain: 800
Blue zoneLight Pollution:
 Dpokrovka Bateckiy R-N Novgorodskoy Obl, Russia
 Oct 2nd, 2024
2 h 46 m
931
Resolution: 8000x5196 px
Scale: 43128 KB
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Comments

Great work! I'm impressed by the depth of detail you achieve with such a modest aperture and wide field.
But what is protruding into the aperture, causing diffraction in the form of two dark cones on bright stars? Or is a lens pinched somewhere? Have you looked into it?
10 Oct, 2024 Reply
Smirnov Andrey Replied to Smirnov Andrey
By the way, this effect isn't visible in the previous shots. I've had this happen on single frames when the field of view passed through wires, but with your 53 frames at 2 minutes each, these effects should disappear when stacked. The only thing left would be spider webs on the lens (just kidding!).
10 Oct, 2024 Reply
Smirnov Andrey Replied to Smirnov Andrey
By the way, this effect isn't visible in the previous shots. I've had this happen on single frames when the field of view passed through wires, but with your 53 frames at 2 minutes each, these effects should disappear when stacked. The only thing left would be spider webs on the lens (just kidding!).
10 Oct, 2024 Reply
Anastasiya Tretyakova Replied to Smirnov Andrey
Thank you! This effect is created by the Samyang 135mm lens at its widest aperture. If you stop it down a bit, the effect disappears, but it's a shame to lose the light-gathering capability, so this is the result, at the expense of bright stars.
10 Oct, 2024 Reply
Anastasiya Tretyakova Replied to Smirnov Andrey
In the previous shots, this effect is actually present where I shot with an open aperture.
10 Oct, 2024 Reply
Smirnov Andrey Replied to Anastasiya Tretyakova
Understood. So there is local stress at the edge of one of the lenses. Most likely, either something got between the lens and the cell, or a collimation/centering screw (if present) is applying a bit of excess pressure.
11 Oct, 2024 Reply
Smirnov Andrey Replied to Anastasiya Tretyakova
Understood. So there is localized stress at the edge of one of the lenses. Most likely, either something got between the lens and the cell, or a centering/adjustment screw (if present) is applying a bit of excess pressure.
11 Oct, 2024 Reply

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