Richard, Thank you :) The self modification is removing the "IR Cut" filter from in front of the cameras sensor. A lot of the deep space nebulae (not all) but the majority, are giving off light in the Hydrogen Alpha wavelength of the electromagnetic spectrum. Ha light is light that is given off by objects that have heat (infrared) same thing. The CMOS sensor in a dslr is naturally sensitive to this light, it can pick it up. The manufactures of the camera have to put a filter in front of the sensor to block the IR light from reaching the sensor so the pictures look normal. This really sucks for astro because you can't shoot a lot of these nebulae, and enhance a lot of galaxy shots with that filter in place. One problem with removing the filter is that if you replace it with nothing, the autofocus on the camera stops working for daytime use. To fix this you have to purchase a piece of glass to replace the IR cut filter. Baader makes some, they are not only made to replace the ir cut filter, but also made to help clip light pollution and to help prevent internal reflections that cause star bloating in AP. You can still use the camera with daytime photography by using a custom white balance to get the red out of the pictures, or by using an external IR CUT filter that goes on the lens of the camera instead of in front of the sensor. I used the instructions by Gary Honis here to do my modification. If you are uncomfortable with doing it youself, Gary also offers the service for about half the price you will get at other places. http://ghonis2.ho8.com/rebelmod450d1.html There is a lot more info on that site. Cheers! David Richard Tenney wrote:
David, excellent images all. What sort of "self modifications" did you make to your XSi? I also have one, but have yet to try any astro photos (nor do I have a good tracking mount). /R
--- On Mon, 10/12/09, David Rankin <David@rankinstudio.com> wrote:
From: David Rankin <David@rankinstudio.com> Subject: [Utah-astronomy] NGC 6949 (New Image) To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Monday, October 12, 2009, 11:46 AM
After tweaking out my setup and spending more than an hour trying to get everything setup. I was able to capture this one last night before the spotlight in the night came to ruin my astrophotography.
Enjoy!
http://www.slas.us/gallery2/main.php?g2_itemId=2557&g2_imageViewsIndex=1
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