How to capture Big Dipper on DSLR?

[bharat]

Inspired by some of the astrophotography pictures posted on this site, I decided to make an attempt in my own small way!

With my Nikon D5000 mounted on a tripod (with the 18-55mm lens), I tried to shoot the Big Dipper. Alas! all that I managed to capture was an illuminated sky with the star appearing as very faint dots in the background. My questions are -

1. In first place, with the above set up, is it possible to get a decent picture of the Big Dipper stars?

2. The settings that I used were as follows:

i. Aperture: Wide open
ii. Exposure time: varied from 3 to 5 seconds
iii. ISO: varied from 1000 to 2000

The pictures were taken with the 18-55 lens on full zoom position.
In each picture, the camera exposre meter indicated the correct exposure amount.

3. Should I try again with different settings? For eg. reduce the aperture and increase the exposure time?

4. SHould I take the pictures in RAW format or is jpeg ok?
5. Is any post editing necessary to eliminate the sky illumination?

Thanks!

[swat_pup6433]

the ans to question no.1 is YES with the stated setup you could get pretty decent shots of constellations. BUT. it actually depends on where you are and how decent you want it to be. in dark places far away from light pollution, you could get nice bright stars with dark background. but for places like singapore with serious light pollution you would get kind of a red sky background and longer exposure would just make the sky glow even worse. which would make very low contrast photo of the constellation. wose case you would over expose the sky and not see the stars at all.
also regarding the exposure time. the longer the focal length of the lens you are using to take the photo, the shorter the maxium exposure time u can get on a still tripod before the stars start trailing and appear like streaks due to the earth's rotation.
regarding the maxium exposure time with regards to focal length. you could look aroudn in the forum abit. i remember there was a post about maxium exposure time for pinpoint stars on a still tripod.

hope it helps.
clear skies!

[Clifford60]

http://www.singastro.org/viewtopic.php?t=3800

The link to the post about the max exposure time by Weixing.

[orly_andico]

ideally you'd want a light pollution filter because Singapore skies are so brown :-)

(DSLR imagers call this the "brown fog of death" or the extinction limit)

unfortunately I don't think light pollution filters are cheap if they are large enough to screw onto the front of a camera lens...