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Images Taken Through a 6 Inch Newtonian with a Webcam

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Astrophotos Taken Through A Discovery 6 Inch Newtonian



As an example of what can be accomplished with a small telescope, this page presents images captured with a Discovery 6 inch Newtonian (f/5) telescope using a Modified QuickCam Express Webcam. The telescope is a favorite of mine because with its six inch aperture it can help me see a lot, yet it is light and compact enough to be easily moved around my yard. The vendor I bought it from no longer sells that model, but the Celestron Omni XLT 150mm Telescope is virtually the same instrument.

The features of the telescope that make some photography possible is that it is on an equatorial mount that is reasonably solid, somewhat facilitated by the light weight aspect of the short f/5 telescope. Also, the telescope mount is clock driven.

I replaced the original clock drive on this telescope as it had a hand-held speed controller that I didn't find convenient, and the motor caused some vibration. I was lucky to find an old style sychronous motor drive with built in clutch at JMI Telescopes. Since the mount already had slow motion controls, the clutch driven motor has proven sufficient for my photographic needs.

The QuickCam web camera was converted into an astro-camera by disassembling and retrieving the circuit board to be mounted on the end of a plastic bottle bottom that happened to fit tightly on my T-adaptor. Images were taken at either prime focus or through a 3x to 4x Barlow. The higher than common Barlow projections were necessary because of the short focus (750 mm) of the Rich Field Telescope. You can see more details of how I constructed it at the aforementioned link, but affordable web cam conversions like the Orion StarShoot Solar System Color Imaging Camera are readily available for photographing solar system objects through your telescope.

Some of the images shown here indicate a 5 inch f/6 instrument. For those, I used my 6 inch f/5 telescope stopped down to 5 inches. The Barlow projection images were made using my trusty old Edmund Barlow. I've recently semi-retired the old Edmund Barlow by purchasing a Televue 2x Barlow. By focusing the telescope without the stop, then taking photos with the 5 inch stop in place, I found that I decreased critical focus problems by increasing the depth of field. It's the same principle as using a higher f-stop on a camera.

All of the moon photos except the Apennines image are composites made by averaging from 2 to 50 or so of the best images for the region. My earlier efforts involved taking a few individual snapshots, but I learned that it was better to make movie strips (avi files) which would let me get tens of images of each target. I now typically take 20 second or so movie exposures, yielding 200+ frames. These are then thinned down to the best 60 or so frames by my Yorick image stacking program and then registered (aligned), and averaged together for a final image.






Click On Any Image For A Larger View

The Equipment: Discovery 6" f/5 Newtonian on equatorial mount.
Clavius Image, Feb 2, 2009, Modified QuickCam Express Webcam, 6" f/5 Newtonian, 3x Barlow. Stack of 15 images.
Webcam Pic of Lunar Terminator

Composite of 3 frames taken with 6 inch f/5 Newtonian (masked to 5 inches) and Quickcam Express webcam. Shots were all taken at prime focus, each photo is a stack of about a half-dozen frames.

Moon Image, Albategnius Region, Modified QuickCam Express Webcam, 5" f/6 Newtonian, 3x Barlow.
Moon Image, Straight Wall Region, Modified QuickCam Express Webcam, 5" f/6 Newtonian, 3x Barlow.
Moon Image, South Polar Region near Tycho, Modified QuickCam Express Webcam, 5" f/6 Newtonian, Prime Focus.
Moon Image, Plato Region, Modified QuickCam Express Webcam, 5" f/6 Newtonian, Prime Focus.
Moon Image, Apennine Range Region, Modified QuickCam Express Webcam, 6" f/5 Newtonian, 3x Barlow.
Moon Image, Alpine Valley Region, Modified QuickCam Express Webcam, 5" f/6 Newtonian, 3x Barlow. Averaging but a few images brings out the subtle variations in surface color.
Moon Image, Eratothenes crater, Modified QuickCam Express Webcam, 5" f/6 Newtonian, 3x Barlow. I always thought I could glimpse about 3 mountains in the crater. These images, excellent for the 6 inch f/5 I think, show the mountains clearly.
Moon Image, Tycho crater, Modified QuickCam Express Webcam, 5" f/6 Newtonian, 3x Barlow.
Jupiter Image, Oct 16, 2000, Modified QuickCam Express Webcam, 6" f/5 Newtonian, 4x Barlow.
Jupiter Image, Nov 1, 2010, Celestron NexImage, 6 inch f/5 Newtonian stopped to 5 inch, 3x Barlow.
Saturn Image, Oct 16, 2000, Modified QuickCam Express Webcam, 6" f/5 Newtonian, 4x Barlow.


Personal Notes

I took these photos with my short focus 6 inch Newtonian. I found that stopping down the instrument to 5 inches after focusing helps insure the images are in sharp focus. One could certainly do as well with greater convenience using something like a Celestron NexStar 5 SE Telescope. It's more compact, has about the same aperture, and has a clock drive. I've done that, with the results shown on the NexStar 5SE Astrophotos web page.

Most of these images were obtained with my modified web cam, and a few of the more recent ones with a Celestron NexImage camera. If you have a laptop, that form of photography is reasonably convenient. Early on I only had a desk top computer (used for the planetary and Lunar Appenine photos), and dragging out the equipment was quite a chore.

I now use an HP laptop running Puppy Linux to take my pictures. It has a web cam software application that lets me take movies (avi files,) from which I select the best frames. The Celestron NexImage comes with a software package that runs in Windows called RegiStax. The program can be used to stack frames from a web cam movie to produce a final, optimal image.

As I use Linux much more than I use Windows, I use a Yorick script I created that aligns and averages the images to produce the type of images shown here.

Many people have had good results with general purpose digital cameras. The advantage to using them is that they are self contained -- no computer required. I've constructed a mount so I can use my Fuji digital camera. The Mercury transit images at The 2" Lens were taken with my Fuji digital in this manner.