David Hall's Page

 

About Me:

I am an amateur astronomer located in northern Jefferson County near Eureka, MO. Most of my imaging is done from my front yard.
My primary astronomical interest is in taking astrophotos of the Moon.

Equipment:

Telescope:

Currently I use a Stellarvue SV102ED refractor for lunar imaging. It is 102mm (4in) and has a focal length of 709mm. It has excellent optics. It is light weight, and easy to carry out to the mount and install. Its not a true APO, but I don't see any color fringing.

Tracking Mount:

Celestron CG-5. It is semi-permanently installed in the front yard. Its rated for 20 lbs, so the 10 lb Stellarvue is easy. Lunar tracking is excellent for a least 1-3 minutes. Polar alignment controls are pretty rough. Its been sitting outside since Fall of 2009 and still works fine. I cover the upper part with a couple of heavy plastic bags and an inverted plastic trashcan ("Dome by Rubbermaid").

CCD Camera:

I am using an Imaging Sources DMK31AU03. Image is 1024x768 and monochrome. Good lunar images are taken these days by stacking many (100s-1000s) short exposure video frames. Short exposures will "freeze the seeing" normally present due to atmosphere distortions. This camera has good sensitivity (0.05 lux) which permits short exposure frame captures of the Moon even near the terminator. The DMK31AU03 is capable of 30fps at full resolution through the USB port. At that rate 1800 frames can be captured in 1 minute. Some of the top imagers take 3000-4000 frames per video. That many frames should insure quite a few good frames are captured. Also, stacking frames reduces the noise in the final image. Image sharpening techniques yield better results when there is lower noise in the image.

This camera's pixels are 4.65um x 4.65um which is smaller than most cameras. Smaller pixels give better resolution all else being equal. High resolution images is what I am after.

I decided on monochrome primarily to eliminate any possibility of codec problems some people reported with color cameras. With B&W it is Y800. With monochrome I can experiment with filters and maybe improve resolution under certain condition. (Also, my instincts say that deBayering a color video might reduce resolution. I don't have any proof of that statement, but that bias was a part of my decision.)

The DMK31AU03 isn't as cheap as a webcam, but it has done a great job for me and I am completely happy with it.

Accessories:

Televue PowerMates - 2.5x and 5x. With these I can get focal lengths of 1772mm and 3545mm in addition to 709mm straight from the SV102ED.

Electric Focuser - I bought a motor and hand control from Orion and built an adapter to attach the motor to the tube of the SV102ED. Its probably impossible to take high resolution lunar images without an electric focuser. At best it is extremely frustrating.

Software:

Image Capture: Either Craterlet or IC Capture.

Image Stacking: AviStack.

Post-Processing: AstraImage for deconvolution and wavelets.

 

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Subpages (1): Lunar Images
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