Last Sunday night was a mostly clear night out in the Cahuilla valley. That provided the opportunity for some astronomy and astrophotography. The night before might have been a bit better, but it was cold with the temperature already below freezing at 9pm. Yes, that’s really that cold, but it’s awfully cold to be outside with a telescope.

Earlier in the day, I had installed the new drive motor and tested the new controller for the CG-5 mount. Everything seemed to be working fine. The first order of business was to collimate the scope. The last time I had critically looked at the collimation of the C-8 the out-of-focus view of a star was quite asymmetric. It took a good 45 minutes to get it done, but I am now confident that the C-8 is in good collimation.

The Moon was getting close to full, only two days away, so I was planning on Lunar imaging. Dew became the first problem. I believe that my prior CG-5 motor controller box was destroyed because I used a hair dryer to dry the corrector plate while the drive controller was plugged into a Radio Shack 6v transformer (not a regulated unit but a little brick). Given this, using batteries for the CG-5 drive was required.

The next problem was that my new ImagingSource firewire camera did not respond. The computer did not see it. I tested the firewire port and it was fine. Gloom. The I remembered that I did bring my trusty Phillips ToUCam Pro. I got that set up and focused on the Moon.

I have always wanted to try creating a mosaic. I shot four shots around Copernicus crater to create my first mosaic. I processed each AVI as consistently as possible, in the end, doing no wavelet or exposure correction in Registax. I combined the four images in Photoshop, using the built-in panorama capability. Registax had been shifting the histograms of the stacked images which made the composite uneven; I turned off that option in Registax.

After combining the images in Photoshop. I did all the processing in PixInsight (now a commercially available product!). I had to crop the image before deconvoluting the image as the white space caused errors in processing. here is the processing story.

1. I changed the image format to 32 bit depth, and then doubled the pixel depth by increasing the resolution. Even though this added no data (and probably introduced noise), I could not get decent deconvolution results at the lower resolution.
2. The combined image had some strange color tints to it, probably the result of creating the mosaic. I extracted the luminance and worked with that.
3. I then used the Regularized Van Cittert deconvolution algorithm in PixInsight to sharpen the image. The tutorial they have is excellent. I used a standard deviation of 2.75 and a shape of 1.5, with standard noise reduction and a 0.15 increase on the highlight in dynamic range extension. That final bit was important so I did not clip the bright areas during deconvolution. This step was the key step in creating the image.
4. The next step is where I created two versions with different contrast profiles. On the first, I applied a default HDRWavelet transform to the image to bring up the dark areas without clipping the whites. In the end, this led to a more even image overall, but one with more contrast in the details. On the second, I skipped the HDRWavelet transform.
5. On both versions, I applied a moderate noise reduction with GREYCstoration and a final tweak to the contrast with curves.
6. Final steps were to shift to 16 bit integer, then move to Photoshop to save as web size.

This is version 1, with a sharper contrast in the details, but flatter overall.

The second version is here. It is a bit softer in contrast.

I’d be curious to see which version people like better.