One of the most basic types of astrophotography and yet equally stunning is that involving star trails, particularly
around the celestial poles or immediately due east or west. In addition to capturing the motion of stars around the
north pole which are circumpolar and, hence, never rise or set, we also have the ability to capture seasonal
constellations and stars in such photos, thus allowing for different opportunities during different seasons. Star trail
photos also provide direct evidence that our planet rotates and does so at a rate of 15° per hour. Furthermore, by
studying the arc for a particular star, especially as far away from the pole as possible, one can indirectly estimate
the length of the (total) exposure which often ranges from seven to eight hours in duration and is totally dependent
on the end of astronomical twilight one evening and its onset
the following morning.
Many star photos are centered on Polaris, a double star system which represents our quickest means to locating the
north celestial pole, for it lies less than 1.0° from it, and is an excellent starting point for the polar alignment
of a telescope (and finding your way home if you are lost!). Due to the extended length of the typical exposures
involved, the best film for such work is Kodak Elite Chrome (ISO 100) whose reciprocity failure is nearly zero or
Fujichrome Velvia and Provia (ISO 50 and 100) emulsions with equally impressive curves! With respect to equipment, it
is rudimentary, for a camera with extended exposure capibility is required along with a firm tripod and shutter
release and locking cable. It is also preferable that the camera used have a mechanical shutter so that battery
consumption and power does not become an issue during mid-exposure. The final requirement is a location with dark
skies - the darker the better so that the trails and their colouration will be as bright and contrasty as possible -
with, preferably, an interesting foreground which can be used to enrich the final result.
Note: According to Greek mythology, mermaids are the daughters of Triton, eldest son of
Poseidon and Amphitrite, and who graced the seas and oceans as demigods. Believed to number approximately 3000, they
are cited by the epic poet Homer in The Odyssey and represent beautiful sea nymphs whose head and torso is human whereas
their legs were a tail fin similar to a fish. They would express their anger by making the seas very rough for both ships
and sailors whereas the seas would be very calm when they were at peace. They were stunningly beautiful female creatures
who quite often would lure sailors and their ships with their singing to wherever they wanted leading to both good and bad
outcomes for the ships and their crew. The stunning metal statue below is the work of the acclaimed sculptress Natalia
Mela (1923-) and was erected at the Old Harbour of Spetses Island in 1993.
Proper Star Name: Polaris Bayer Letter: á Ursae Minoris Tycho Catalog: TYC 4628-237-1 SAO Catalog: SAO 308 Luminosity 2290 +/- 282 x Sun Distance: 431 +/- 26 light yrs RA / Dec: 02h 39m 31s / +89° 17' 39" B-V Color Index: +0.570 mag Magnitude: 1.98 |
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Date: Aug 18-19, 2017 21:50 - 04:15 UT+3 Location: Old Port, Spetses, Greece Equipment: Canon EOS 6D Baader BCF2 Filter Canon EOS EF 28mm/f1.8 USM @ f7.1 Exposures: 385 min (190 x 120 sec) (RGB) 010 min (005 x 120 sec) (Dark) ISO 1000 JPG Fine Image Format 5472x3648 Image Size Custom White Balance Manual Mode Continuous Servo Mode Software: Startrails V2.3 Photoshop CS5 Processing: Dark Frame Reduction Layers and Lighten Resampling Unsharp Masking JPG Compression |