Star Trail - 1
Star Trails : A long exposure pointing towards Pole star(dhuruva Nakshatra) will result in star trail.i.e star moving across sky.Technically speaking,earth's movement.
This was taken with 15min exposure at f2.8,17mm focal length using bulb mode.
The dark blue sky is due to white balance set to incandescent.
Bascially,to get a clear view of stars,one has to move out of city's light pollution and the chosen day should be a new moon day or nearer(else's moon's light will offset start's light).
One of the challenges faced in long exposure in bulb mode is sensor' getting heated up leading to noise in the picture.Best recommended method to take star trail is to take photos in contionously for long hours without using bulb mode and stich them.
I have taken photos with bulb mode and long hours led to noisy picture.
Here is a very nice photo of star trail taken on the same day,same place by pratik,using long exposure technique.
Me,Pratik were planning to do Start trial for couple of months and it was happened on early morning of 5th march.Pratik has been doing quite a lot of research on the star trials and been sharing lot of techniques.When we reached our place of shooting(open fieldss,some 100km from Chennai),first challenge we had to encounter was the direction.A good star trial needs photo pointing Pole star,which normally appear to be static.Normally the Pole star appear in North side.We didn't have astro maps or compass to identify the direction.Mathew,one of our fellow photographer came up with google's Astro app which pointed the right direction of pole star,else we would have ended shooting in wrong direction(mean one cannot get the circular effect,but just an arc..).
It was a quite a good learning for all of us.Now we know what and what not to do for a good star trial.