stars

I'm wanting to take a few snaps of the stars when i venture down south to Devon, England. that way i can get rid of the light pollution.

I've had a look through a couple of posts but no one has really given any advice on how long the exposure should be and what settings are needed beforehand.

could anyone give any advice on this matter.
thanks

You need to be aways from the lights as much as possible for the light pollution.

Exposures will depend on your camera, but for crisp stars no longer than 30 seconds.

My settings are 1600 iso f2.8 @ 30 and 20 sec. for most.
I will also shoot at 3200 iso.

I've been shooting stars for a long time with marginal success - mostly due to the conditions I've had. Astrophotography is dependent upon so many factors that it is often hard to predict the outcome of a photo session. A couple of things I've learned:

1) The sky can look fine to your eye but a long exposure can see things you will not.

2) Light pollution is VERY hard to escape and any amount will affect your photos. Don't assume that because it looks dark it is dark - long exposures can find the light pollution your eye can't see.

3) Wide angle lenses are almost a requirement if a stable and accurate tracking system is not used. A normal tripod and a wide angle lens (say 18mm) is good for up to about 30 seconds. Some simple trackers for exposures in the minutes category are possible without much expense but will still not work very well with long lenses. The kind of mounting system used for a telescope is required for long lenses (which are the same as a telescope anyway). An equatorial mount is required for very long exposures (> 5 minutes) or an altitude/azimuth mount for exposures between a few seconds to 5 minutes - approximate times of course.

4) Atmospherics, including humidity and 'seeing', will have a dramatic effect on long exposure photos of the sky. Seeing is the term astronomers use for the amount of disturbance in the air that causes stars to twinkle and apparently change colors. Clarity of the air and air temperature are also factors. How these will affect your image is always a difficult question to answer.

5) Calculating an exposure time for your circumstances will be difficult - I've never gotten it exactly right myself although I've captured a few pretty good images. It is best to settle on a specific target and take many images of different exposures and camera settings to, in effect, do a super bracket for the photo. I vary the ISO, exposure time, and even the aperture to capture a wide range of camera settings.

6) Don't neglect focus. For wide angle it is less important than narrow angle shots but in either case don't assume setting your camera on infinity will produce great results. Take a couple of sample exposures and then using your LCD, zoom in on a bright star and see how well focused the camera really is. I actually tape the focus ring in place (you should always use manual focus of course) so that it doesn't move after I've gotten a good focus.

Hope some of that helps.

BBB

Good tips. What about PP? I've read threads about blending multiple exposures to reduce noise etc. Plugins? Tips?

I would just add that you need a wide angle because above 10 seconds you'll see stars moving on your picture. You can reduce this effect by pointing at the celestal north, this will give you the impression that stars are moving around the north.

Unless you live in a very polluted area, noise can mostly be corrected by your camera. Most of the canon have a functionality to clean noise for longer exposures.

Composition of several pictures is not really an option, stars are moving!

I understand stars are moving, but I'm sure there is software around that aligns them to make the photo clearer. Perhaps it is specific for mounted cameras for telescopic shots like the ones Nighthound in the nature forums here takes. Absolutely breathtaking. He takes many exposures and combines them.

Stacking software exists to take multiple short exposure images and combine them to have the effect of longer exposure. I haven't tried it with photos taken by a camera. Most of the benefits come from using many very short exposure captures like the frames from a webcam. I know there are applications used to stack photos but each varies in the details of how many reference frames are needed, whether a lenscap-on exposure is required to filter thermal noise, that sort of thing. I recommend posting in the Beginner's forum of Cloudy Nights (http://www.cloudynight​s.com …eads/ubbthreads​.php?Cat=0) and asking the telescope crowd. They are very helpful.

BBB