Startrail - What have I done wrong?
Startrail - What have I done wrong?
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Discussion

JimNotJon

Original Poster:

761 posts

238 months

Sunday 13th February 2011
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As the title says really. Went out to do some star trails last night after grasping the understanding of a lot of exposures merged with the startrail software creat awesome pics, but why do my start (i only used 5 pictures here) go in a straight horizontal line and not in a circular fashion as I have seen?


VxDuncan

2,850 posts

263 months

Sunday 13th February 2011
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Think it's simply that the camera is pointing in the wrong direction! Star trails will show best when the camera is pointed at the celestial pole (ie just of the pole star in the Northern Hemisphere). Using a wide angle lens, pointed North ish will show them best. If you imagine a sphere rotating on an axis, you've pointed the lens at 90 deg to the axis of rotation, where the trails are parallel to the axis of the lens.

rhinochopig

17,932 posts

227 months

Sunday 13th February 2011
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Agreed. Pointing the wrong way. Still a nice pic though

Easy way to find the pole star - at the end of the plough are two stars, draw an imaginary line up from these two stars and there you will find the pole star.

Rich K

906 posts

285 months

Sunday 13th February 2011
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rhinochopig said:
Agreed. Pointing the wrong way. Still a nice pic though

Easy way to find the pole star - at the end of the plough are two stars, draw an imaginary line up from these two stars and there you will find the pole star.
this may also help (courtesy of stellarium)


AndWhyNot

2,359 posts

228 months

Sunday 13th February 2011
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Face north for circular star trails. The other thing that affects the appearance of your trails is focal length - looks like you weren't that wide angle and longer lenses have the appearance of straightening the trails because effectively you're zooming in on a crop of the wide angle frame.

ESE or WSW will give you diagonal star trails which curve in the corners. Dead south gives a frown effectfrown

As an aside, looks like your trails skipped a little and you were using uneven exposure lengths. I try to pick a single exposure length so the ambient light remains the same throughout the stack. Personally I like the direction you've composed this for the foreground lighting but if you'd had the moon behind you you'd have been able to expose a stop wider/ longer without losing the star trails to the glow from the moon, so they'd have appeared brighter against the sky.

Fordo

1,572 posts

253 months

Sunday 13th February 2011
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I'm curious, whats the benefit of stacking over just having a really long exposure?

Must give astrophotography a try.. (i'm not hardcore enough- I think i'll wait till it's warmer in the summer!)

AndWhyNot

2,359 posts

228 months

Sunday 13th February 2011
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Fordo said:
I'm curious, whats the benefit of stacking over just having a really long exposure?
http://www.pistonheads.com/gassing/topic.asp?h=0&t=937787 smile

JimNotJon

Original Poster:

761 posts

238 months

Sunday 13th February 2011
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OK that's great, I was thinking last night that there was one thing I needed to remember, and that was it. I will go out and try on the next clear night.. few and far between at the moment.

CVP

2,799 posts

304 months

Sunday 13th February 2011
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With so much light pollution around here I thought I'd try the planes coming into land instead. unfortunately the speed they come in does give the dashed line approach frown Camera now back on tripod having attempt number 2 with a longer shutter speed - fingers crossed for a better outcome


plane trails by CVP1, on Flickr