[Michael Piziak]

I've ordered a wireless remote control and think I may photograph the night sky at long exposure. Any tips ?

I found this info on the internet:

"When photographing the night sky with a long exposure, exposures of 15 minutes or longer will show the rotation of the Earth. You’ll need a wide-angle lens and a sturdy tripod, of course. You’ll want to use a cable release to eliminate camera shake of any kind, as it will RUIN your photo. Focus the lens to infinity and set the camera to B "Bulb" shooting mode. Set your aperture between f/2.8 and f/4 for optimal results, and depress the remote to open the shutter. You should keep your ISO at 100 to keep the digital noise at a minimum, because the sky is so dark and less prone to producing digital noise when the exposure is above 15 seconds. To complete the photo after your desired elapsed time, depress the remote again, and release the shutter."

[interested_observer]

The exposure time is substantially less than 15 minutes in order to not capture "star trails". 5 minutes is the most you can get using the O-GPS1 (and a K5/II/IIs or K3 body) and therefore using the sensor stabilization for star tracking (AstroTracking feature). Or you can use a tracking telescope mount (motorized) that will also remove the earth's rotation. With a telescope mount you can track all night - even with a barn door tracker. However with just a camera - you are limited to about 600/fl seconds.

• The rule of 600 or 600/focal length gives a good estimate in seconds of the exposure time (to try to not capture star trails).
• ISO - 800 is good, 1600 is better. You may need or want to use some noise reduction in post processing.

Here are some links....

• Dave Morrow Photography: Dave's Free Star Photography Tutorial
• Lonely Speck - Learn How to Photograph the Milky Way: Tutorials, Reviews, Workshops + More
• How to Shoot the Night Sky (Introduction to Astrophotography) - Digital Photography School

Also, head on over to ....

• https://www.pentaxforums.com/forums/6-pentax-dslr-discussion/113178-astrophotography.html

[Michael Piziak]

Thanks.
Perhaps I should have made it clear that I wanted to capture star trails
http://www.exposureguide.com/images/night-sky-photography-tips/night-sky-photography1-e.jpg

[Adam]

There are a few inaccuracies there. First of all, infinity on your lens may not be true infinity, so verify correct focus via the viewfinder or live view. This was probably the most challenging thing for me when I was shooting in the dark in the middle of nowhere

Last time I shot night photos I used a 35mm F1.4 lens and I recommend being as close to wide-open as you can, as the extra light makes a difference. My best photos were taken at F1.6 to 1.8.
So a couple of tips here:
-use a sharp lens
-never use a zoom lens

Since the shutter speed controls how long your star trails will be, you will have to either use a very short shutter speed or a very long shutter speed for good photos. You will need to adjust your ISO accordingly. My best non star trail pics were taken at 4-6 second exposures, whereas the actual star trails went anywhere from 10 to 30 minutes.

If you shoot really long exposures, it's a good idea to enable slow shutter speed noise reduction (aka dark frame subtraction). This adds extra processing time equal in duration to the original exposure, but it's well worth it if you're already going out of your way to shoot for several seconds. If you don't like waiting, bring a second body.

Another technique is shooting many shorter exposures and stacking them, especially for stars.

Adam
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[jtorral]

Funny I see this thread. I just opened a brand new site for astrophotography. When you get your shots feel free to post some there. IT would be awesome to see members from the forums I frequent post their astro pictures there.

Astronomy Photo Gallery | Astrophotography.photos

YOu can also see a press release on Astrophotography.photos Website Launches | PhotographyBLOG

[jimr-pdx]

Practice, practice* - what you like may be different from others who have done this, so try everything at least once!

*And a spare battery

[gifthorse]

A sturdy tripod is a must! An alternative, and in some ways better choice, is to cradle the camera on sandbags on the ground. (excluding earthquake country.) Any movement at long exposures will 'kink' the star trails. Get away from lights, at least 30 miles from any large towns. Shoot when there's no moon up. Moonlight will wash out the sky, making the stars hard to see. Longer focal length lenses produce longer trails, shorter focal lengths produce shorter trails (for the same exposure duration). Pointing the camera toward the pole will produce shorter, curved trails, pointed east or west will produce longer, straighter trails. If you use exposure times of less than 30 seconds, consider using the camera's built in intervalometer. A flashlight with a red lens will be real handy. If you can get one of those lights that you wear on your head, that's ideal. Compose so that there is something (trees, buildings, etc) in the frame to provide context, otherwise it's just streaks on a dark background.

[interested_observer]

Here is a good guide for capturing star trails

• How To Photograph Star Trails - Photography by James Vernacotola

You need a dark place - and here is a map to find a dark location.

• Dark Sky Finder

It also works better when there is no moon - so that is on a 28 day cycle. In between, you can catch good shooting times after sun down and before moon rise, or after moon set and before sun rise. TPE will give you the times based on your location. The embedded topographical maps are also good to find a location with some interesting landscapes if you so desire.

• The Photographer's Ephemeris

Stellarium is great to give you an idea as to where to aim the camera to get the greatest concentration of stars - essentially the milky way.

• Stellarium

You can use any post processing utility, however Gimp has some additional tools and features

• GIMP team revitalizes astrophotography tools |

[Eagle94VT]

I am still trying to work on keeping the frost off the front lens - here is what happened after my first overnight time lapse!

[Aaron28]

oh boy! frosty!