Photography Method

Afocal Point-and-Shoot

The first set of photos were taken about a month after getting my Orion XT10i so they are fairly basic, using a point-and-shoot camera, simply by holding the camera (a little 7.1MPixel Pentax Optio L30) up to the eyepiece, and using it pretty much in Auto mode, with a little use of the optical Zoom as well. The pictures were taken over about a half-hour period on 25/01/08 01:40-2:00am.

From the few photos I loaded onto my PC, I then used Adobe Photoshop CS2 to inspect and make slight Levels adjustments and Crop the pictures, and discarded any that were too dark or blurred, leaving the photographs shown below.

Really the point-and-shoot images are nice because they are a keepsake; they remind me of the excitement of seeing Saturn "for real".

As photos they're not great. The Auto mode results in many of the shots being over-exposed, and blurred. As I remember these were handheld against the eyepiece, ie. no bracket to hold the camera steady.

The Optio L30 has an ISO range of 64 to 3200, although the Auto mode used ISO64 for the darker shots, and the brighter shots ranged from ISO120 to ISO3200, and all exposures were 1/4sec. Apertures were generally f/3.1 to f/5.9.

Click each photo to view it full size, and after viewing hit your Back key to return to this page.

If your mouse cursor changes to a magnifying glass icon (+), you should be able to click to increase the picture to its full size.

The pictures have been optimised for quick download, however there are quite a few large images - so please be patient while they load.

The middle photo below represents fairly closely proportionally what you see through the 25mm EP + 2xBarlow.

  

The right-hand photo below is the sharpest I was able to take at this time. When you actually view through the EP the planet is bright and sharp-edged, and you can distinctly make out its moons, although they don't appear in this photo.
I was unable to make out the Cassini division (the main central dark band in the rings), but the rings are almost nearly edge on at this time, making it increasingly difficult to view the rings properly.

 

The right-hand photo below appears snowy simply due to over-exposure and noise, they are not stars.

 

 

This last photo below is very over-exposed so as to try to get the moons. To the eye through the EP the moons can be seen very clearly, but in this photo one larger moon is just visible as a smudge to the bottom. (See the webcam images further down for a better image of moons).

 

Webcam Photos of Saturn

Through the 25mm EP alone, to the naked eye Saturn appears quite small. Using the Barlow, and then the 10mm brings its size much nearer (now at 240x magnification), but I remember being astounded by the fact I could see not only the planet and its distinctive rings, but also Saturns moons, like little stars huddled around it. That was awesome, and made me realise I wanted to get a better eyepiece offering higher magnification.

This shot was taken a few weeks after I got my scope, now in March 2008, after buying a Philips SPC900NC Webcam from EBay.

I used it to take a 640x480 resolution AVI movie simply by aligning Saturn at the leading edge of the field of view, then leaving the scope static, and just letting Saturn traverse the field of view (which takes about 30 seconds). Afterwards I then used K3CCDTools which is a piece of software that will gather the best frames of the movie, enhances, aligns and stacks them all together, to make one composite picture, and this is the result.

Again its early days for me, but pleasing nonetheless to have taken the movie and then got to grips with the software, and it shows reasonable results can be obtained without motorised equatorial tracking! I might add that the sky was not particularly bright or clear on that evening either.

First have a look at the movie footage captured directly through the telescope, as it gives you a real sense of what you actually see (note that this movie was shot at 640x480, but is shown here compressed to half size at 320x240).

Click for Saturn movie footage - requires Quicktime or similar viewer.

K3CCDTools was used to capture the movie and perform the post-processing to align the frames, stack them and enhance to give this single still shot.

Saturn's Moons

Secondly, (see next photos below) using the same method I adjusted the Webcam settings to deliberately over-expose the image. This is why Saturn now looks bloated and blurry, but this enables five of the tiny moons orbiting Saturn to be captured instead.

Click for Saturn's Moons footage

Again processing using K3CCDTools gives the following final image. The image is not particularly sharp because it is zoomed in. Think about it. The actual CCD chip in the (cheap) webcam is quite tiny, and the moons project light onto probably only a few pixels on the chip (and the movie was taken at 640x480 resolution, at 10 frames per second), so the granularity or pixelation is unable to provide a good sharp image. Remember that several things contribute to problems here;

  • Minute movements of the scope
  • Bad visibility due to turbulence, poor transparency, poor seeing.
  • Low resolution webcam movie
  • Summing together of about 300 frames to produce the image, helps increase contrast and brightness, but also depends on how accurately the software can align the frames to produce the composite image.

You see we're making the best of a bad situation. A basic dobsonian mount does not have equatorial tracking, so we are relying on software to align poor movie footage. With motorised tracking you would have a steady image which could utilise longer exposures (with less webcam gain), resulting in better contrast and colour, and more detail at higher magnification.

Still - its mighty clever stuff, challenging to do it, and rewarding to get the results, even if they're somewhat rudimentary. As I see it, I am learning techniques I didn't know before - getting the best out of what equipment I can afford - and it's FUN!

Could you see 5 moons in the original movie footage?

Saturn has 31 known moons. Of them, Titan is the largest (seen at left in the above photo), and is the second-largest in our solar system. The other satellites have icy surfaces and many craters. Mimas has one crater that spans one quarter of it's diameter. Iapetus is another which is an enigma. It's surface appears to be divided into two sections. Most of the moons, which are small, were probably captured asteroids, and did not form with Saturn.

The capture I took of Saturn was on 19/3/2008 at precisely 22:54 GMT. Using this time I reproduced the relative positions of the planet and its moons by putting the date/time into Stellarium to discover exactly which of Saturn's satellites I was looking at, and this screen capture provides a record of the moment.

In fact comparing this with the photograph reveals that my picture actually shows 6 moons with Enceladus very, very faint just to the left of the rings. The visible moons are from left to right; Titan, Rhea, Enceladus, Iapetus, Tethus and Dione.

Saturns Moons positions

For more fascinating information about Saturn's moons, see Journey Through The Galaxy website.

Photos of Saturn taken with Celestron C6 SGT (SCT)

Saturn's Anniversary

The following photos were taken using my new Celestron C6 SGT telescope with my SPC900NC webcam. It is now March 2009 and you can see how much more tilted Saturn has become in comparison to the above photos, with its rings now almost edge-on to us. My C6 is mounted on a CG5 German equatorial mount to which I have added Goto capability. An EQ mount makes all the difference for astrophotography.

These pictures were created from just two different AVI movie captures from the webcam, but show the results of processing at different stages, and using different techniques. A 2xBarlow was used with the webcam, and also the 2xMode during post-processing to double the size of the image.

This is the basic image after selecting frames for good Quality and least Difference, then aligning and stacking using K3CCDTools.

The next pic below is after some basic tweaking of the Channels Histogram and some slight adjustment to reduce Gamma to produce a brighter image with a darker background.

The next picture uses the above, but now adding using the Unsharp Mask Filter to give some more edge definition and general sharpening of the image.

This photo is a variation but showing the Gamma increased, resulting in a general brightening of the image, and the Unsharp Mask filter being increased with some fairly hefty Radius and Amount values, which creates a patterned mottling particularly noticeable on the background. Not very attractive!

Another variation on the above with even heavier Unsharp Mask. While this causes the mottled pattern to become annoying it does accentuate some of the banding on the planet.

Generally the best results are obtained with subtle modifications to the original.

The next few photos are taken without the 2xBarlow (ie. just the webcam at prime focus). Unfortunately K3CCDTools decided it would crop off one edge of the rings, and I didn't notice until too late.

Now some adjustment to Channels Histogram and Gamma, followed by some Unsharp Mask. Notice how a very faint double-band around the planet is brought out in the right-hand photo (and one of the pictures I forgot to rotate thru 180 degrees).

Now taking a different approach using Registax V4 this time to do all the aligning/stacking pre-processing, and then post-processing, using its Wavelets to sharpen the image. Also the Red/Blue alignment adjustment feature was used to reduce slightly the effects of chromatic aberation.

Finally the same Registax image post-processed using Photoshop to add a number of different filters; Curves, Levels, Brightness/Contrast, Unsharp Mask, and some subtle Gaussian Blur.

While Registax is a bit complex to learn, in combination with Photoshop I think it produces the best results.

 

Useful Links

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  • K3CCDTools - This software allows you to take better control over your webcam to capture movie footage or still shots to your computer for later enhancement by K3CCDTools, or another software such as Registax. It is reasonably priced and has many advanced features that give special control over exposure and gain that your standard Webcam software may not provide. K3CCDTools is particularly of interest because it includes settings that hook into a "long exposure modified" webcam (Note that long exposures are useless without proper equatorial tracking).
  • http://burro.astr.cwru.edu/stu/index.html - Journey Through The Galaxy website, for amazing facts and information about our Planets, Solar System and Galaxy.
  • Stellarium (for free, this is a terrific piece of software!). Gives a very realistic representation of the night sky in real-time, very quick and easy to use, looks great.