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Author Topic: Night Sky Exposures  (Read 5240 times)
Photolandscape
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« on: November 01, 2008, 01:24:36 PM »
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I am going to be in the Eastern Sierras and Nevada in a week or two. I want to try some time-exposure shots of the sky while I am out in the middle of nowhere, perhaps with an old building or other objects in the foreground. I have seen some outstanding examples of this sort of thing from Art Wolfe and other photographers.

I have a Leica M8 + 15mm, 35mm, 90mm, and 135mm lenses for it. And of course, a great Gitzo tripod. The only meter I have is the one within the camera.

I would like to take some very long exposures, showing the movement of the stars in relation to Earth.

So of course I should stop down the lens. I have an ND filter that fits my 35mm lens. Any other thoughts on how best to do this?
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wolfnowl
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« Reply #1 on: November 01, 2008, 04:52:22 PM »
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Well, it's not rocket science... and you're shooting digital so you don't have to worry about reciprocity failure.  Find a good place out of the wind, set the camera on 'B' for a multi-second exposure, and have at it.  If you have more or less complete darkness, you can have exposures of an hour or longer.  According to Leica the M8 is threaded for a standard cable release, so you'll need one of those.   After exposure, have a look at what your histogram/ viewfinder shows you.  Being an M8 you don't have to worry about MLU. If you have a flashlight, see if you can get a red filter for it so it doesn't completely destroy your night vision.  Also, if you are going to be turning on a light, try to keep one eye closed you only lose night vision in one eye.  Of course, turn the light off between exposures.  DOF only comes into play if you're shooting sky trails against an earth-based foreground.   As you know, or might know, because of the earth's rotation stars show up as concentric arcs on long exposures.  If you aim the camera at Polaris, you'll get concentric circles instead of just arcs as the earth's axis is more or less in line with that star.  Also, different stars are different colours, so be prepared for white, red, yellow, green, blue...  There's probably more, but trial and error is a good teacher.

Mike.
« Last Edit: November 01, 2008, 11:34:40 PM by wolfnowl » Logged

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jasonrandolph
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« Reply #2 on: November 01, 2008, 07:40:12 PM »
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Mike gave some excellent advice.  I've found that a lot of long exposure photography relies on trial and error, since light meters don't work very well in the absence of light.  The good thing is that you will have instant feedback with the M8.

I don't know how the Leica sensor performs with regard to noise, but this may become an issue.  When exposing any digital sensor for more than a second, noise may seriously degrade your images.  If you have Long Exposure Noise Reduction in the M8, you may want to try shots with and without it.  I find that shots that I intend to convert to B&W yield better results without any in-camera NR.  For color work, I prefer to use it.  I use a D300 though, and every sensor is different.  

Also be mindful of hot pixels.  The longer your sensor is "on", the more heat will be generated.  If you have a shot with star trails and some stars don't seem to be moving, those dots aren't stars; they're hot pixels.  You can clone them out in PS, but they may play a role in your shots.

The last thing I would say is be mindful of your battery situation.  If you are going to make some very long exposures, you should bring along some spare batteries.  This is an example of where film wins hands down.  Battery life is finite, and if the batteries are dead, so is the camera.

Anyway, best of luck!  Despite all the complications involved with night shooting, it's a lot of fun, and it can produce some very unique images.
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vandevanterSH
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« Reply #3 on: November 02, 2008, 03:55:32 PM »
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"Also be mindful of hot pixels. The longer your sensor is "on", the more heat will be generated. If you have a shot with star trails and some stars don't seem to be moving, those dots aren't stars; they're hot pixels. You can clone them out in PS, but they may play a role in your shots."
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Can the heat as shown by "hot pixels" cause permanent damage to the sensor?  

Steve
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feppe
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« Reply #4 on: November 02, 2008, 04:13:48 PM »
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Quote from: jasonrandolph
The last thing I would say is be mindful of your battery situation.  If you are going to make some very long exposures, you should bring along some spare batteries.  This is an example of where film wins hands down.  Battery life is finite, and if the batteries are dead, so is the camera.

Many (most) modern film cameras require the battery to be functioning to keep the mirror up, so film in itself is not a solution.
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John Camp
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« Reply #5 on: November 02, 2008, 08:44:09 PM »
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How long can you expose before you start to get star-point enlargement due to motion?

JC
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Paulo Bizarro
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« Reply #6 on: November 02, 2008, 10:25:05 PM »
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I have done quite a few of this type of photos. I use a EOS 1V and Velvia 100 film. I have used 16-35 and 50mm lenses, depending on the location. The best results I have gotten thus far have been taken in nights with no moon (new moon phase). With these conditions, I can expose for 4 or 5 hours, and get excellent trails around the Pole Star. My advice:

1. Set up your shot before it is dark; find an interesting foreground subject while you can still see;

2. Use a sturdy tripod and a cable release that allows the camera to be locked in Bulb. Otherwise, you will have to keep pushing the cable release button for a few hours...

3. I have used intermediate apertures in the lenses, say around f/4 to f/5.6. Stopped down more than that, it is more difficult to capture the fainter stars.

In the end, it is really easy.
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jecxz
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« Reply #7 on: November 03, 2008, 04:43:43 AM »
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Quote from: John Camp
How long can you expose before you start to get star-point enlargement due to motion?

JC
Just 1 minute will produce a slight star line. I suggest, however, leaving your shutter open for 30 minutes or more. Great results for an hour plus.

I also suggest that you experiment with pointing your camera towards Polaris (north star).

I have a few examples of star/night long exposure on my website, but a simple Google search will yield beautiful examples. Good luck to you.

Kind regards,
Derek
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jasonrandolph
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« Reply #8 on: November 03, 2008, 09:34:56 AM »
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Quote from: feppe
Many (most) modern film cameras require the battery to be functioning to keep the mirror up, so film in itself is not a solution.

Steve, you are right with regards to modern 35mm SLRs and some medium format models.  I guess I was thinking of my own situation where I have an old 4x5 Crown Graphic and my Voigtlander Bessa rengefinder which uses batteries only for the meter.
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jecxz
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« Reply #9 on: November 03, 2008, 10:29:13 AM »
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I've shot H2 with film - battery worked fine fine for about three hours (didn't shoot longer than that but my battery wasn't dead either). Could have shot much longer. Temperature was not warm either. Don't know about other cameras. Battery drain while shutter is open is probably minimal.
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clearescape
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« Reply #10 on: November 12, 2008, 11:58:29 AM »
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Be mindful of the moon first and foremost, it can be your best friend and worst enemy.  But experimentation is always the best advice lowest ISO possible, cable release and your good

Eric
Eric Blackman Photography
« Last Edit: November 12, 2008, 11:58:52 AM by clearescape » Logged
Sigi
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« Reply #11 on: November 14, 2008, 07:55:01 AM »
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Quote from: Photolandscape
I am going to be in the Eastern Sierras and Nevada in a week or two. I want to try some time-exposure shots of the sky while I am out in the middle of nowhere, perhaps with an old building or other objects in the foreground. I have seen some outstanding examples of this sort of thing from Art Wolfe and other photographers.

I have a Leica M8 + 15mm, 35mm, 90mm, and 135mm lenses for it. And of course, a great Gitzo tripod. The only meter I have is the one within the camera.

I would like to take some very long exposures, showing the movement of the stars in relation to Earth.

So of course I should stop down the lens. I have an ND filter that fits my 35mm lens. Any other thoughts on how best to do this?


Have a look at this article on Luminous Landscape:)

http://www.luminous-landscape.com/tutorials/d60-night.shtml

Sigi
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bill t.
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« Reply #12 on: November 14, 2008, 12:49:38 PM »
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I have used Image Stacker for star trails and other types of night work.  Highly recommended!

Instead of a single long exposure, you can make several shorter exposures (with minimal time in between), then add them together.  This has many advantages, the main of which is greatly reduced noise.  Another is that if an airplane or headlights or electronic flash intrudes in your shot, you lose only a slight amount of arc rather than the whole sweep, you can just call it quits at that frame and add up good exposures leading up to the problem frame, or just skip the problem frame when you add and fill in the gap with a little Photoshop work.

http://www.tawbaware.com/is_help/imgstack_help.htm#stack

The author has a few star trail shots in his galleries, worth looking for.

http://www.tawbaware.com/maxlyons/ST_IMG_2...s_Startrail.jpg
« Last Edit: November 14, 2008, 12:53:34 PM by bill t. » Logged
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