The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. A quick review of the iStar Phantom FCL 140-6.5 Explore Scientific, 16 inch / F 4.5. The cookie is used to store the user consent for the cookies in the category "Performance". Article: Takahashi Mewlon 250 - An Astrophotography Perspective Recent Reviews. This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other. The cookies is used to store the user consent for the cookies in the category "Necessary". The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". The cookie is used to store the user consent for the cookies in the category "Analytics". These cookies ensure basic functionalities and security features of the website, anonymously. Necessary cookies are absolutely essential for the website to function properly. In your case, the origin of the ghost spike is a star outside the imaging field, but inside the field of view of your telescope □ This disperses the light more and tends to make the spikes smaller! But keep in mind that the light from diffraction ist not gone away, it will spread around the star. This can be remedied by a strip of velour attached to the side of the struts of the spider. This effect occurs with all secondary spiders, regardless of the design! On sheet metal spiders this effect is often not as clearly visible as on milled spiders, because the alignment of the spider arms is not perfect and therefore the diffraction is not as constructive in the second order compared to milled spiders. This is physics and with your telescope everything is fine! The brighter the star is, the more clearly these “ghost spikes” become visible. In between (between the first and second spike) is a minimum that can be seen as a dark region. The reason for the “ghost spike” is the secondary spider! What you normally see as bright spikes on stars is only the first diffraction order! What you see as ghost spike is the second diffraction order. The reflections are caused by bright stars that are outside of the DSLR’s field of view (red), but within the telescope’s field of view (green): Michael explains the reason for these reflections in his comment below. The big question is how to prevent these reflections… maybe darken the inner tube and the spider vanes… Update So far, I’ve no other explanation for it. So I think these reflections must be caused by bright stars outside the field of view. May 9, 2022īoth stars (Solafat and Sheliak) are around mag 3.5. If I check the field around my field of view in Stellarium I see a bright star on the reflection opposite side. Ghost reflection in the lower mid left area But there is also a reflection in the lower mid left area. No flats, darks or bias.Īt first glance no reflections were visible in yesterday’s image. Yesterday I did M57 again, but with the DSLR 90° rotated to see any difference in the reflections.
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