Finally found the southern polaris (stair trail attempt)

[siddr20]

Well i think i may have found the southern polaris. Well im pretty sure i have.
But the stupid clouds came in the way and i couldn't experiment further.

I normally do stacking for star trails, but i thought i give one long exposure a go.

Here is the result with the clouds coming over :(

http://i7.photobucket.com/albums/y276/siddr20/1-4.jpg

Hope you like it.

Hopefully the next couple of days i can get some clear skies.

[Nighthound]

You found it alright. Wow, there really is no bright star at the center to help locate it.

Great shot.

[Canon Pete]

nice shot and I agree with Steve , thats gotta be a PITA to locate due to it being near other dim stars. Saying that , you guys in the Southern skies have got some really amazing targets to go for.

Pete

[Celestron]

Congratulations !! Job well done !

[siddr20]

Thanks guys :)

Had a quick question. How do you all get black backgrounds? I have seen plenty of star trails with black background. Mine always comes up blue no matter what. Is it due to the light pollution?

[Joergeske]

I would venture to guess that many of the pure black skys you are seeing are done in PP, the sky even at night has blue in it. To get a darker sky with sharper trails though try and find a night where the moon is either empty, or has not risen yet.

[siddr20]

Cheers for that :)

Also what do you mean the moon is either empty??

[troypiggo]

I'd say he means "new moon" when there's less light pollution.

You familiar with using curves or levels in PP?

[siddr20]

I have played around with it a few times, but im no professional at it.

What will the curves do?

[troypiggo]

I asked because you asked about getting black backgrounds. You can use levels or curves to play with the tones in images. Think this is what people mean when they refer to "stretching". Levels is probably simpler to start with. Curves takes a little more to get used to.

I'll try to explain generically what I'd do, but add some comments after relevant to your image above.

So what you'd do is open your image, go to your levels tool, make sure the channel is set to "value" or whatever your PP software equivalent is (ie don't pick red, blue, or green channels yet), and see the sliders under the histogram? You want the left one (for shadows/dark tones) to slide from left to right until it hits the left-most part of the histogram where it drops back to zero. You can go further to the right (try it) but you will get what they call "clipping" where you're telling it to output black where the tones should be greys. You'll lose detail, particularly for very faint dark colours like nebulae. Ideally you'd pick the point where the histogram just touches the bottom of the graph.

Now do the opposite thing for the right-most slider (for highlights). Slide it from far right to the left to the point where the right-most part of the histogram hits the bottom/zero of the graph. Again, don't go too far left or you'll clip some of the lighter tones white.

What you have just done is "stretched" the dynamic range (think that's the right term) of your image by telling it to output tones only within the range captured by your camera. You'll get much more detail.

Now play with the middle slider (midtones) up and down the histogram until you get the midtones just the way you like.

That's the basics. You can play with the red, blue, and green channels if you like, but you'll find that will change the white balance of the image. I'm finding I need to drop the red channel midtones for my astro images, but it's all experimentation.

Now for specific comments on your image above. As someone mentioned, you don't need the sky black. And you'll find it does snuff out some detail. Plus, you'll notice the histogram of your image above doesn't meet the bottom axis until the left-most part of the graph anyway. It's already clipped. All that means is that some parts of the image you took are pure black or severely underexposed. So you won't be sliding the shadows slider to the right, unless you want to clip for some reason (who knows, it might look better to you).

As you slide the highlight slider left, you'll notice the clouds more. And playing with the midtones slider you'll see more detail where there was none before.

Pretty cool, hey? :)

That's pretty simple to do. Curves is similar to the above, but much more control. Bit more complex to get your head around, though.

[superdiver]

Very cool, how do you stack them, i have figured out how to?

[troypiggo]

Deep sky stacker (http://deepskystacker.free.fr/english/index.html) is free and easy to use. Some pretty good tutorial/explanations on their site. Pretty much click n go.

[superdiver]

I use Macs, any suggestion for stacking on a Mac? I did find DSS, but no Mac version last I checked...sad...

[troypiggo]

Don't know about Mac, but a quick google turned up this:

http://keithwiley.com/software/keithsImageStacker.shtml

[superdiver]

That does look promising. Am looking for a tutorial to make sure it does what I am after.

[siddr20]

I asked because you asked about getting black backgrounds. You can use levels or curves to play with the tones in images. Think this is what people mean when they refer to "stretching". Levels is probably simpler to start with. Curves takes a little more to get used to.

I'll try to explain generically what I'd do, but add some comments after relevant to your image above.

So what you'd do is open your image, go to your levels tool, make sure the channel is set to "value" or whatever your PP software equivalent is (ie don't pick red, blue, or green channels yet), and see the sliders under the histogram? You want the left one (for shadows/dark tones) to slide from left to right until it hits the left-most part of the histogram where it drops back to zero. You can go further to the right (try it) but you will get what they call "clipping" where you're telling it to output black where the tones should be greys. You'll lose detail, particularly for very faint dark colours like nebulae. Ideally you'd pick the point where the histogram just touches the bottom of the graph.

Now do the opposite thing for the right-most slider (for highlights). Slide it from far right to the left to the point where the right-most part of the histogram hits the bottom/zero of the graph. Again, don't go too far left or you'll clip some of the lighter tones white.

What you have just done is "stretched" the dynamic range (think that's the right term) of your image by telling it to output tones only within the range captured by your camera. You'll get much more detail.

Now play with the middle slider (midtones) up and down the histogram until you get the midtones just the way you like.

That's the basics. You can play with the red, blue, and green channels if you like, but you'll find that will change the white balance of the image. I'm finding I need to drop the red channel midtones for my astro images, but it's all experimentation.

Now for specific comments on your image above. As someone mentioned, you don't need the sky black. And you'll find it does snuff out some detail. Plus, you'll notice the histogram of your image above doesn't meet the bottom axis until the left-most part of the graph anyway. It's already clipped. All that means is that some parts of the image you took are pure black or severely underexposed. So you won't be sliding the shadows slider to the right, unless you want to clip for some reason (who knows, it might look better to you).

As you slide the highlight slider left, you'll notice the clouds more. And playing with the midtones slider you'll see more detail where there was none before.

Pretty cool, hey? :)

That's pretty simple to do. Curves is similar to the above, but much more control. Bit more complex to get your head around, though.

Thank you so much for taking your time to write up this. It was helped a lot and i will try and post up the results in the next startrail i do :)

Thank you once again mate!!