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actually.. its more of 1st attempt at star trails / bulb mode and my new 18-270mm tamron lens. comments needed so i can try out more shots while im still up in the mountains in canada!

Main thing would be to get rid of all that terrestrial light. Turn off all the lights if possible or go somewhere its dark outside.

Then I would open up the lens as far as it will go, Increase the ISO as far as reasonable and use the in-camera noise reduction. Make sure you have fresh batteries though, especially in Canada in Winter! Also , make sure the moon has set

Check the recent posts. there have been some great examples of Star Trails recently from Broken Hill. bigv is one name that comes to mind. Anyway, they used a technique of layering lots of shorter duration exposures. Worked a treat.

Mr Darcy wrote:Main thing would be to get rid of all that terrestrial light. Turn off all the lights if possible or go somewhere its dark outside.

Then I would open up the lens as far as it will go, Increase the ISO as far as reasonable and use the in-camera noise reduction. Make sure you have fresh batteries though, especially in Canada in Winter! Also , make sure the moon has set

Check the recent posts. there have been some great examples of Star Trails recently from Broken Hill. bigv is one name that comes to mind. Anyway, they used a technique of layering lots of shorter duration exposures. Worked a treat.

a few questions.
1. should i on/off my on lens VC?
2. advantages/disadvantages of doing layers/30min exposure shot?
3. Why push up the iso and not just use 100?

lastlyyy
will try to walk around tmr. being an asian in -5 weather aint fun! and thanks for the quick comments

1. should i on/off my on lens VC?

I don't understand the question. What is VC?
If oyu mean VR (Image Stabilisation), this should always be off when you are using a tripod (or substitute)

2. advantages/disadvantages of doing layers/30min exposure shot?

I can't really comment as I have never used the layering technique. It does produce a staccato effect though. See links below. It does have the advantage that you can change the battery partway through, so you can get some REALLY long exposures. I expect you would also be avle to control how bright the scenery is using the layering effect too.

3. Why push up the iso and not just use 100?

Stars are faint. The more light you can get onto the sensor, the brighter they will appear. Open the lens wide to get as much light in as possible, then increase the sensor sensitivity to make the most of what light you do get. Of course, the higher the ISO, the more noise will affect your shot, so use the Long Exposure noise reduction to counter this as much as possible. OTOH if you cannot get rid of the ambient light, a low ISO will help keep the scenery dark.

These are three recent Star trail posts
http://www.dslrusers.net/viewtopic.php?f=18&t=35457&sid=27eda4e7101e2ecb1dfaf0810a4be826
http://www.dslrusers.net/viewtopic.php?f=18&t=35447&sid=27eda4e7101e2ecb1dfaf0810a4be826
http://www.dslrusers.net/viewtopic.php?f=18&t=35456&sid=27eda4e7101e2ecb1dfaf0810a4be826

and one I did a while ago for a competition here:
http://www.potofgrass.com/gallery/c21/Eternity002
From memory, this was a 20 minute exposure, which ran to 40 Min with the NR turned on. There was a single outside light on about 100m away. That was enough to illuminate the clothesline. And the moon had just come up - though still below the effective horizon - which washed out the sky to an extent.

Let me chime in here, firstly image stabilisation needs to be off. Secondly do not use in camera noise reduction because you will end up with big caps between the stars. The trick to getting these right is to shoot as long as possible before the background noise from street lights etc starts to show up in the frame. Selecting a higher ISO enables fainter stars to be detected but again it is a trade off with background light.

Now for the best bit, if you take lots of images and layer them you can beat down the noise issues but you need a minumum of 16 layers to see a reduction in noise and this works for any ISO. 64 layers is the ideal and any more than that is a real bonus. This means if you are in a light polluted area you can still do trails but it may mean that you would have to take 250 20 second images and layer but it will work! Lastly, personal preference but I always like to have some sort of fore ground object in the frame which is reasonable well lit to give a reference..

You are well on your way, make these changes and enjoy the mountains whilst you are there - at least for the next week the moon will not be a problem for you.

Secondly do not use in camera noise reduction because you will end up with big caps between the stars.

Can you explain this more Big V?
My understanding was that the long exposure NR takes a second frame for the same duration WITHOUT opening the shutter, then subtracts anything that shows up on that from the "real" image. Thus digital noise is cancelled without otherwise affecting image quality. ? This won't affect stray light though.

What you seem to be saying is that is not how it works in real life.

1. Definetly turn the VR off on a tripod.

2. Layering effect helps reduce noise in the image, and also does alow some comtroll over the scenery, i.e if someone drives up with their headlights on only one frame is runined not the whole exposure.

3. You definetly need to let as much light as possible into the camera, and on a really dark night running a high ISO and wide lens you would be surprised how many stars a camera will pick up, Untill i get of my proverbial and buy a decent timer remote im happy with the intervalimeter on my D200 once i worked it out it worked flawlesley, the only times i stoped it was to check exposure as the moon was rising.

Cheers
Adam

Mr Darcy wrote:

Secondly do not use in camera noise reduction because you will end up with big caps between the stars.

Can you explain this more Big V?
My understanding was that the long exposure NR takes a second frame for the same duration WITHOUT opening the shutter

Which means that you are not able to make another image until that second image has finished. If you want to get continuous/contiguous trails, you'll be wanting to make each exposure immediately following the prior one, with minimal delay between frames.

Using in-camera NR would prevent this from happening.

Gary is correct...

OK. Now I follow.
I was thinking in terms of a single long exposure. No need to take a subsequent image this way. It is what I have always done in the past. I have controlled ambient light by choosing my location carefully. Sometimes driving hundreds of km to achieve a dark sky. Set the camera up. Dial up a 20 min ( or two hour!) exposure, go for a cuppa, then come back a few hours later to recover the camera.

You are within the paradigm of layering. The trails would come out as morse code if NR was turned on.
I'll have to give it a try.

Greg, the beauty of using the layering method is two fold, you can take star trails from any location no matter how bad the light pollution and this gives you the creativity to frame the image any way you want. As an example I have done this from the centre of Adelaide with a statue pointing to the star trail. Secondly it will beat the noise down which would be an issue on a series of short exposures at higher ISO settings. You get a great deal of flexibility using this method.

Big V wrote:Greg, the beauty of using the layering method is two fold, you can take star trails from any location no matter how bad the light pollution and this gives you the creativity to frame the image any way you want. As an example I have done this from the centre of Adelaide with a statue pointing to the star trail. Secondly it will beat the noise down which would be an issue on a series of short exposures at higher ISO settings. You get a great deal of flexibility using this method.

Could I ask how this layering is done? Manually in photoshop? this would require a lot of memory have that many images open at the same time? Am I missing something here?

Thanks for the info Big V.

If you write an action and then run it as a batch under file automate, it will open 1 image at a time copy it paste it onto the first and then close it, uses very little memory and works really fast.