4 replies to this topic

[MattSimmons]

Can anyone tell me what might be causing the stars flares in this image? The scope is a SW 190 Mak-Newt, ASI2600MM and Antlia V-Pro RGB filters. Scope has had the focuser replaced, but otherwise stock. Collimation with a laser, cheshire and autocollimator is spot on. About 12 hours of integration time. I love this scope and I can live with these flares on bright stars, but I would like to eliminate them if possible. Thanks!

 

 

[deSitter]

Can anyone tell me what might be causing the stars flares in this image? The scope is a SW 190 Mak-Newt, ASI2600MM and Antlia V-Pro RGB filters. Scope has had the focuser replaced, but otherwise stock. Collimation with a laser, cheshire and autocollimator is spot on. About 12 hours of integration time. I love this scope and I can live with these flares on bright stars, but I would like to eliminate them if possible. Thanks!

 

That looks like diffraction from the focuser tube impinging into the light cone.

 

-drl

[deSitter]

Note that diffraction artifacts are somewhat paradoxical. A focuser tube impinging on the light path will cause two thick spikes which would be hard to see visually. The spikes are opposed across the star. Likewise a 3-vane spider will cause 6 diffraction spikes.

 

-drl

[italic]

I have one of these scopes but haven't come across the flaring you've encountered (yet). It looks like something is presenting as slightly oval, so as mentioned, it could be the focuser tube crossing the light cone. The primary is bigger than the corrector's aperture, so even if off-center, the primary position shouldn't be the problem. Mine was modified by the previous owner to be more appropriate for imaging, so I don't know what the stock secondary mirror and stalk look like, but perhaps there's a surface catching light somewhere on the secondary assembly, like the edge of the secondary glass. Do you have a dew shield on it that might be flexing into the light path? Do you have any exposed threads that aren't painted with matte paint?

 

Also remember that Navi is an incredibly bright star so you'll get flaring and reflections on it no matter how good your scope is. Do you get flaring on all filters or only one or two? How long is your focuser draw tube? I have a Moonlite and the tube does not enter the OTA when in focus.

[luxo II]

The filter. I had an Antlia one that caused similar flares on every star, it was unusable in either of my scopes.

Edited by luxo II, 08 November 2024 - 07:39 PM.