[APML] Esthetical effects filters

[Emmanuele Sordini <vega@bloomingstars.com>]

Hi everybody,
I occasionally run into some widefield piggyback pictures (i.e. no 
telescopes involved, only telephoto lenses) which have some pleasing 
effects on the stars in them. In particular:

1) Some of them have the brightest stars which are bloated way beyond what 
you could expect from their apparent magnitude. What kind of filter is used 
to achieve that effect? Perhaps by utilizing what is called a "fog filter"?

2) In some others (but fewer anyway) the brightest stars have many nice 
rays/points. Since those rays do not come from a telescope secondary 
mirror's spider vanes, what filter is used in this case? Perhaps a n-point 
star (n=6, 8...) filter?

I'm all ears...

Thanks in advance and clear skies,
Emmanuele 

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