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forestgnome
08-15-2007, 10:48 PM
I caught this Perseid fireball streaking through the Big Bear (Big Dipper) on August 11th...


http://i96.photobucket.com/albums/l190/forestgnome/8-11-07-copy4perseid.jpg

Happy Trails :)

Steve M
08-15-2007, 11:14 PM
Thats cool! Thanks for sharing.

Brad
08-16-2007, 06:33 AM
I went out on the dock to watch and there were too many low clouds to see much. Thanks for sharing. Any others?

Mike D
08-16-2007, 11:04 AM
I'm not a photographer, but I understand it takes a lot of knowledge and high end equipment to capture the night sky like that. What equipment do you use?

Bill O
08-16-2007, 11:20 AM
Did you enhance the stars in the big dipper or are they really that much brighter?

forestgnome
08-16-2007, 07:34 PM
Thanks for comments!

Mike D., no end equipment needed for such a shot. I used a cheap tripod(lightwieght for hiking), Canon Digital Rebel 300D, and a Sigma lens at 24mm. This can be done with any camera capable of taking a 20" exposure.

Mount camera on tripod, set aperature to wide setting, focus on infinity. Brachet exposures, because the meter is not reliable under these conditions. Those are the basics.

Tips: Learn how to focus at infinity in daylight with a distant peak, etc., because you cannot do it at night. Focus at infinity and make a mark on the lens barrel for reference at night. Also, try setting up in your home at night without lights for practice. A red led headlamp is extremely useful.



Bill O, no filters or anything. The Dipper stars are that much brighter than surrounding stars.

Happy Trails :)

Charlie
08-16-2007, 08:35 PM
that is cool nice shot ,thanks for sharing

Charlie
08-16-2007, 08:38 PM
you should summit this for the Photo Journal

Bill O
08-16-2007, 09:08 PM
Any hot pixels after 20 seconds?

forestgnome
08-17-2007, 06:07 AM
Any hot pixels after 20 seconds?

Yes. If you look closely you'll see some small, bright red "stars". Those are actually hot pixels. I will put the image back in Photoshop and zap those. :)

Mike D
08-17-2007, 09:38 AM
What the heck is a hot pixel? That is to say, what causes it?

Bill O
08-17-2007, 12:21 PM
What the heck is a hot pixel? That is to say, what causes it?

It really is caused by heat, and therefore becomes a problem during long exposures when the image sensor generates too much heat. People who are really serious about long exposure will use elaborate devices to cool their cameras, probably with mixed results.

Of the millions of pixels current cameras capture its rare to have more than 20 or so hot pixels. And they are usually very easy to clone out, especially since it is just one pixel. On my camera they appear to be bright green.

JimS
08-17-2007, 08:32 PM
It really is caused by heat, and therefore becomes a problem during long exposures when the image sensor generates too much heat. People who are really serious about long exposure will use elaborate devices to cool their cameras, probably with mixed results.

Of the millions of pixels current cameras capture its rare to have more than 20 or so hot pixels. And they are usually very easy to clone out, especially since it is just one pixel. On my camera they appear to be bright green.

There is a long exposure noise reduction feature on my camera (20D), where the camera compares the picture just taken to an 'exposure' of the same length directly afterwards with the shutter closed. This subtractive comparison between the two 'shots' cuts alot of noise and hot pixels. I'm not sure how many cameras have this, but it's worth looking into if the Rebel has it...