Saturday, May 19, 2012

Getting Ready for the Annular Solar Eclipse

This is a test shot of the sun with a new solar filter I just created for my 300mm camera lens.  I did this to test the lens and filter combination to make sure there was no problems for the upcoming annular solar eclipse on May 20.  I will be driving to Albuquerque, New Mexico to hopefully catch the "Ring of Fire".

This is the same lens and filter combination taken the same day, but when the sun was starting to set behind one of the Rocky Mountains in Colorado.  The 1st image was taken when the sun was much higher, so the color is quite different from the reddened image of the sun at sunset.  The exposures were quite different also.  The 1st was 1/1600 at f/5.6 ISO 100.  The 2nd was 1/40 sec at f/8 ISO 200.  The slower exposure for the 2nd image is all due to light extinction from the earth's atmosphere at the lower elevation.  All that atmosphere also causes the higher wavelength blue light to be blocked and only the longer wavelength red light to get through.

This is the setup for the above images:  A homemade solar filter over the front end of my Canon 300mm f/4 L IS lens.  There is also a 1.4X Extender to make the focal length 420mm f/5.6.  It is attached to my trusty Canon Xti camera.  All on top of a ball and socket and tripod.  I will also be taking a 70-200mm f/2.8 L IS lens just in case I get lucky and get a chance to shoot the eclipse without a filter with some foreground scenery.

This is the filter I made for the 70-200mm lens.  Very simply made from Baader solar filter material and thin poster board.  I used double-stick tape to hold the filter between two sheets of poster board.  I then rolled a couple of sheets of poster board around the lens to create a tube and used double-stick tape to hold that in place.  The tube is glued to the board holding the filter with a bead of white glue.  Even though the Baader filter material looks wrinkled, it has very high optical quality.

If the weather is clear, my next post will show the results.