5d mkIII long exposures

[wrk4no1]

I do a lot of night photography and also just before sunrise landscape. I want to know how can I get a better dark sky with long time exposures.

Thanks

[Waddizzle]

You could use image stacking to adjust the exposure of the sky, independently of other areas of the shot.  If you're trying to correct high contrast shots, then HDR could be an option.  I cannot say for certain without seeing an example, or knowing what "better dark sky" means to you.

[kvbarkley]

You might not be able to depending on conditions. If there is any overcast or glare from city lights, the sky is not dark. Where are you shooting?

[wrk4no1]

I am on the east coast near the beach. I am interested in shooting some pier shots with stars above.

[kvbarkley]

How close are you to a large town?

[Waddizzle]

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@wrk4no1 wrote:

I am on the east coast near the beach. I am interested in shooting some pier shots with stars above.

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You should post a sample of what you're trying to shoot.  Otherwise, any replies are pure speculation.

I think what you're after is a something best finished in post-processing.  Although I have never tried anything like that [but plan to do so this summer] I don't think HDR would achieve the results you're looking for.  The starscape could likely require very different post-processing than what the pier portion of the shot may require.  It would really depend upon how much light pollutoin is in your area. 

Most areas of the east coast are smothered in light pollution.  Visit the site Dark Sky Finder to see what I mean. 

http://community.usa.canon.com/t5/General-Camera-Discussion/Star-Mapping-Software

The above link is to a recent thread about software that is a virtual planetarium.  Use it to help choose when is a good time capture the shot that you want.  If you're really serious, then you may want to invest in a good compass what includes a declination readout, so that you can measure angles relative to the horizon.

A good image stacking freeware package is called Deep Sky Stacker.   Here is a link to an excellent video at AdoramaTV that shows you how image stacking could be used in landscape photography.  T

https://www.youtube.com/watch?v=yqAXR94X0T8#t=12

The guy, Gavin Hoey, just happens to be photographing a pier on a beach.  Finally, you may wind up using Photoshop to combine two separate shots from the exact same location into one shot.  One shot is a beauty shot of the pier, while the next is a beauty shot of the night sky.  They could be combined using Layers in PS.

[TCampbell]

Deep Sky Stacker is intended for use when the only thin in your images is the stars (no landscape) and you should also be using a tracking head.  It uses the points of light created by the stars as alignment references to "register" the frames so that they all align neatly.  Mostly this is used to allow astrophotographers to reduce noise in astrophotography images.

But this creates a unique problem when landscape is involved because our planet is spinning.  That creates the illusion that the stars are moving and if you stack images with stars and landscape using the stars as a reference for imaging registration then the landscape wont align. 

To get around this you need to get an image in which you capture the stars and landscape together in just one shot.

This creates another challenge... since the Earth is spinning, if the shutter is open too longer then the perceived motion of the stars will result in non-round stars and you'll have elongated stars that aren't attractive.  

On a 5D III (any full-frame sensor camera) use the base value of 600 and divide the focal length of your lens into that value.  The result is the number of seconds you can expose safely... without ending up with elongated stars.  If you used a 24mm lens (just as an example) then you end up with 25 seconds.  If you used a longer focal length, say 50mm, then you'd get just 12 seconds.  If the exposure isn't long enough then the stars wont be very bright and you'll really need to crank the ISO to compensate and now you've got to deal with noise issues.  If you use a shorter focal length... say 14mm ... now you can shoot for about 43 seconds.  

Focusing for stars is hard because the auto-focus wont help you (the stars aren't bright enough to provide the contrast that the camera needs.)  You'll have to manually focus and take your time getting that right.  You will likely need several test exposures to make sure you've got the stars focused to your satisfaction.

If you want to focus stack you can still do that ... once you've got a frame with sharp stars.  BTW, astro-images seldom come out of the camera with dramatic stars.  The sky usually requries a bit of exposure stretching to bring out the details.

[wrk4no1]

Thank you I certainly will check n out that video and find a good image to post up here of what I'm dealing with.

[wrk4no1]

I am located in Virginia Beach area I usly go n out of the ocean front lights to an area with less light pollution.

[Waddizzle]

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@wrk4no1 wrote:
I am located in Virginia Beach area I usly go n out of the ocean front lights to an area with less light pollution.

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TCampbell is the real expert astro-imaging around here, not me. Heed his advice with regard to using a wide angle lens.   It will make a difference in how much light you can gather.  I use a Rokinon 14mm T3.1 cinema lens, which is roughly equivalent to the Rokinon 14mm f/2.8 photo lens. 

Using a good, professional grade tripod and head will make a world of difference in your shots, too.  To reduce camera shake from pushing the shutter button by hand, I use the 10 second timer  in the camera, instead of a remote.  My best starscape images have started off looking like overexposed messes. 

Just be aware that Virginia Beach, and its' surrounding area, is pretty well drenched in light pollution.  If you have never been to a genuine dark site before, then it is hard to appreciate the difference. Being in the middle of the ocean, or at least a 50-100 miles from any shore, on a cruise ship is a good example of a dark site.  Check out the web site I linked.

My first experience with a dark site occurred when I was a young pup in upstate New York, in the center of Adirondack Park, where there wasn't a town with more than a thousand people in it for at least 75 miles in every direction.  The nights were so dark that you could look up in the sky and actually see the dense band of stars, and gas clouds, that make up the Milky Way.  The sky looked like photos you see of the Milky Way.  It was almost mid-August, just in time for the annual Pleaides Meteor Shower.  I was profoundly impressed by the sight of the night sky.

Like I said, I'm guessing that you may wind up combining two processed images into one final result: one being a beauty shot of the pier, and whatever surrounding landscape; the second would be a beauty shot of the sky, which could be created from a series of stacked images.  These shots would have be taken from the identical camera position, so that they can be precisely aligned on separate layers in Photoshop, and later combined into one final image.