Friday, June 22, 2007

Near-IR Imaging

I finally got around to really playing with the NIR filter I bought. It really screws with my camera. I had never really had a good focus, and I finally figured out how to make it work properly. First, the R G and B channels are at very different focuses from each other (chromatic abberations), and to top it off, the proper focus for any one channel is really really far from where I expected. To focus on the Big Island (infinity), I have to put the camera at 3foot focus. Messy huh? Anyways, I've got some good crisp shots and I'm doing the processing now.

One other thing I noticed when trying to stack a bunch of images is how much the images wander. My tripod was "drifting" and "bouncing" with time. When I add together 50 pictures to make a HDR image, I get a bunch of smearing.....

Here's the Mauna Kea telescopes simply added without aligning the images.

Here's the shifts I found - it drifted a bit horizontally, and it bounced & drifted a lot vertically.

After aligning the images (cross-correlating), here's the result. Those who know the summit would be able to find the twin Keck's and Subaru by their shapes. I'm going over to the left-most one tomorrow morning with Liz and Christian to do some observing there. Good thing I'm already night-adjusted.


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