Re: [APML] Esthetical effects filters

["John C. Mirtle" <jmirtle@shaw.ca>]

Here's a couple...
http://members.shaw.ca/spampit/cayley.htm
http://members.shaw.ca/jmirtle/m44.htm

These were done with a glass 8 point "star" filter. They are available in 4,
6 and 8 point - possibly more. There are two types of star filters - glass
or plastic. The glass ones usually are AR coated and work well, even when
left on for the entire exposure. All the stars are sharp. The plastic ones
usually introduce a so-called "soft focus" look. While this may make for
nice romantic portraits, they are totally devastating for astrophotos. Stick
to glass.

John Mirtle
http://members.shaw.ca

----- Original Message -----
From: "Emmanuele Sordini" <vega@bloomingstars.com>
To: <astro-photo@seds.org>
Sent: Wednesday, May 07, 2003 1:18 PM
Subject: [APML] Esthetical effects filters


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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