Filtterit ja halot

[einari]

Jotkut filtterit tuottavat kirkkaisiin tähtiin halo-efektiä.
Tätä on nyt tutkittu:
https://www.researchgate.net/publication/365687384_Understanding_Filter_Induced_Star_Halos

[Pappis]

Lyhennettynä: Johtuvat lähinnä suotimen sisäisistä heijastuksista (päästökaistan ulkopuolella). Eli suotimen laadulla on iso merkitys.

[Harri Räisänen]

"The following conclusions regarding the behaviour of filter induced star halos have been drawn from the various experiments and analyses summarized in this report:
1. The primary cause of filter induced star halos is intra-filter reflections.
2. The angular size of the halo is dependant only on the thickness of the filter glass and the telescope focal ratio. Filter distance from the sensor has no impact on the visibility or size
of the halo.
3. For stars of the same visual magnitude, filters are more prone to generating halos around
hot blue and cool red stars than moderate temperature orange, yellow, and white stars.
4. Filter off-band blocking performance is the primary characteristic affecting halo
generation.
5. The use of anti-reflective coatings can help to reduce halos, but it is a lower magnitude
impact compared to off-band blocking."