Shortly after we published early versions of our telescope program, a local San Jose astronomy buff named Charles Chew -- shown at left, in Steve's driveway -- contacted us for a registered copy of the software, and showed us HIS own program to calculate astrophoto exposures, written in BASIC. A strong friendship was forged and Charlie and Steve still share many anecdotes about observing and equipment, as well as an occasional viewing session now and then.
So, when Charlie acquired a pair of Meade imagers -- the "Deep-Sky" and "Lunar-Planetary" models, inexpensive devices that are well within the affordable entry-level price range, we perked up our ears and eyes. Charlie was kind enough to let us test them on a number of our scopes, ranging from a very simple unguided achromat refractor (an 80mm Orion "ShortTube" f5 richest-field model) to a new Celestron GPS-11 Schmidt-Cassegrain (on a driven alt-azimuth mount, a "goto" scope that finds and tracks any of 40,000 celestial objects in its database, or anywhere in the sky by means of an external control program, such as a star-chart). The results showed that, yes: practically ANY novice who at least understands how to use a scope, can image the Moon with pretty good results, and even get a recognizable planetary image. At least WE could, to our huge relief and delight!
But DSO's are a challenge, using the Meade DSI CCD, that we find too daunting at present. The Meade imager works probably best on a Meade goto scope, so that one can use the software to center and lock the telescope and more easily acquire the appropriate field in the CCD chip. Wth a Celestron or other brand scope, which won't work with Meade's goto drivers, one has to work a bit harder, losing out on the built-in star chart program in the Meade software suite. Furthermore, when imaging objects at culmination, it is impossible to switch easily from the CCD to the necessary "parfocal" ocular directly on the visual back of the scope: it's too close to the base plate of the fork. One must use a diagonal, losing some light and contrast. Frankly, our attempt to get M27 with an f/10 optical system in the severe light-pollution of San Jose -- and with a nearly full Moon just rising, yet! -- didn't yield an intelligible picture, other than the star-field. But Luna and Mars cooperated nicely.
We had one slight glitch during the software installation process: puzzlement over the setup of the USB driver for the Meade DSI (an installation anomaly that is explained on this helpful webpage); otherwise, setup on an old Pentium III PC was straightforward, and though the AutoStar suite program opens and executes rather slowly on a 667 MHz machine, it is workable (display mode of 1024 by 768 pixels is ESSENTIAL, or you'll fail to be able to 'reach' important buttons to make the software function, something we did not realize at first, since our computer display was set at 800x600.)
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But the attempt to install the AutoStar suite in the "astronomically dedicated" system we use in the field for our scope, a brand-new Acer Aspire laptop (1.4 GHz) using Windows XP Home (trademarks apply, ya-da, ya-da...) yielded a result that was almost IDENTICAL to the problems reported in the Weasner website article, above: we quote -- Subject: Meade DSI - First report! Sent: Tuesday, October 26, 2004 07:36:53 From: Roy (roymc@frontiernet.net) Since I am one of the first to get a production model of the Meade DSI CCD camera, I thought I would share my experiences. I spent three days trying to get the thing to work. I kept getting "No Imager" faults every time I tried to run the software that controls the camera. After much frustration trying to get the camera to work, I tried installing the software and camera on my desktop... several tries meaning installing and re-installing the USB drivers ... I finally got it to "see" the camera and thought I had it made. I later installed Desktop Universe and the drivers wouldn't work anymore. More frustration followed... ...I decided to buy myself a new notebook...an HP Pavilion that was configured similarly to my Dell except that it didn't have a wide-screen. I tried to install the camera and drivers. To make a long story short, I couldn't get the CCD camera to work on the HP either... ...On a whim I checked my Windows version. I was running XP with service pack 1. I downloaded service pack 2 and installed it on my system. It worked, and it worked well. ... Roy F, McCabe The upshot of all our testing on three computers is that we are convinced that while Meade has not done a very reliable job with the installer, the star chart software program -- adding the Hubble Guidestar catalog -- is an extremely practical, usable, and simple yet detailed program, one which very quickly yields satisfactory results compared to some of the complicated and fancy ones already on our machine. |
Aside from the bewilderment of learning how to negotiate the tradeoffs in setting the gain and offset, and to prevent a too-bright image at the CCD, swamping the chip, one soon learns how to adjust the exposure time and other parameters, and to begin capturing images. The Meade software can "lock" on a swimming or drifting image on-screen, so that the layering of multiple pictures is seamless and in proper registration (helpful with an alt-az goto scope that doesn't have the most ideal tracking -- and has intrinsic field rotation.)
Our earliest trials were terrestrial images using the Orion 80mm refractor. We got amazingly good results, as attested by the image of our friend Charlie, who was standing nearly a block away! (He had to maintain a very steady stance, causing him to settle into a rather stern expression that reminds one of a 19th century Daguerrotype, done with head-clamp.)
The picture named Moon-dusk-ST80 is our very FIRST attempt at a celestial shot, made with the ST80 and LSI CCD even before dusk had really set in: the sky was still rather bright blue. We tried to subtract a bit of the color and to enhance the contrast. It simply shocked us that we could get a usable image under such conditions, and so easily!
Next, about an hour later -- with a fairly dark sky background on the evening of 15 September 2005 -- we got a better photo of the Tycho region in Moon-Tycho-ST80. And in the subsequent Moon-ST80-2xBarlow -- pretty self-explanatory -- we increased the image scale (and also, of course, the exposure time) for a 'closer' view. These photos are composites of several shots each, in the range of a bit less than 1/10 second exposure to prevent noticeable smearing, since the scope was being used with NO clock drive whatsoever.
Having the Celestron GPS-11 SCT sitting nearby was too much of a temptation, and we quickly switched over to it and made moon-Gassendi-C11 which is more-or-less our very first try with that instrument; we got several similar composites that came out fairly identically. The one that seemed just SLIGHTLY better is the one we used here for the processed version, with unsharp masking and some contrast-stretching. It is a layering of about 10 short 1/25th second exposures.
On the night of 19 September we tried the DSI but decided that our attempt with M27 was doomed to failure in the midst of San Jose light pollution; so we utilized the Moon again. Frankly, TheMoon-DSI does not please us at all; it is too soft, and we had trouble adjusting the exposure on such a high-contrast image source. The device must be better suited to faint views!
Early after midnight on the morning of 20 September, we turned to Mars, nearing opposition and with a diameter of about 16 arcseconds. But the seeing was very poor, and in a high-powered ocular the planetary image danced and twinkled and boiled. We tried to shorten the exposure time to the fastest practical setting but still managed to smear some of the detail and to lose the crispest instants of clear and steady air. And we had to limit the composite exposure so that the limb of the planet did not become excessively fuzzy: so the vague dark markings are rather indistinct. A 2x Barlow was absolutely essential, not only to increase image scale but also to cut down on the brilliant glare. If we do this again, a 3x would be even better: perhaps we can put an extension tube between the 2x and the LSI and refocus. The larger the image on the chip, the better (up to a point) so that one can use a degree of efficient unsharp masking. We couldn't do much; otherwise the small image became too pixellated. So the result is distinctly inferior, compared to the fabulous work during this Mars opposition that has been contributed to the Marswatch website. Well: one can only try, try again. Mars looks perfectly dreadful to the eye, at high magnifications, about 95% of the time during any good opposition; one has to wait for the moments of supremely steady seeing to enjoy detail (see Regina's article about the 2003 opposition), and the morning of 20 September offered no such experiences, as our digital image of the red planet, taken with the C-11 and Meade LPI, can attest.
Incidentally, we assert that it IS at optimal focus. The computer monitor was about 15 feet from the scope, so we carefully adjusted the focus while staring through binoculars at the screen! It must have taken us the better part of an hour to be sure. The softness of the image is due to the seeing (and perhaps to our novice-incompetence!)
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For this evening's test, Stephen and Charlie had studied the manuals more carefully, and were prepared to spend more time in perfecting their results with the deep sky imager. But our observing venue was in the heart of San Jose, California, with naked eye star limiting magnitude of barely 3.5; and light pollution was evident, particularly from "auto row" on the Capitol Expressway, a mere mile off. Our attempt to take a color image yielded an enormous amount of ugly background noise, nasty yellowish-purple pixels that swamped everything else. So we switched to monochrome mode, and were at last, after infinite fiddling with the gain, offset, contrast, and histogram controls, able to acquire two (lousy) images of Messier objects that were nearly overhead: M57 (the "Ring" nebula), and M56. Normally these bright objects are easy to see in the C-11 scope, and really look quite fine to the eye even viewed here in a large city: the "Ring" has distinct shape and good contrast, though the 15th magnitude central star is invisible even at 600 diameters of magnification or even higher, and the globular M56 is a nice, neat, compact bright little knot of stars, partially resolved. But the DSI images were frankly wretched. We spent at least an hour on focusing to try to make certain that the we were getting the sharpest possible image, given the variations in individual short exposures. The light pollution caused a certain background noise and mottling, and an uneven field illumination, that could not be entirely corrected by substracting dark frames. M57 was essentially "unphotographable" except in a longish exposure that tended to burn in the brightest parts of the nebular shell; and seeing caused the central star to wobble and smear, though it could be seen clearly enough on individual frames. We presume that the major stumbling block was the f/10 focal ratio of the C-11; no telecompressor lens was conveniently available. So we don't feel comfortable in judging the DSI or its software under a test that is not best-case: for not only was the optical system "too slow" for optimal exposures, but also the variations of seeing were exaggerated by the longish exposure times, probably an order of magnitude lengthier than if the camera were used on Charlie's f/4 Meade Schmidt-Newtonian (not ready yet for our tests.) We offer these two pictures, below, as being entirely unsatisfactory first attempts made "all wrong", in that we used a poor environment and an optical system that was too slow. That something is seen, under the circumstances, is perhaps reassuring. But we nevertheless felt a bit disappointed that our tests failed to yield the results that Johnny Horne raves about in his review in the October, 2005 issue of Sky and Telescope.
RIGHT: Charlie Chew jokes with the binoculars that we had to use to see the screen from the Celestron scope, while the individual frames of M56 slowly build up. The M56, 57 images (below) are composites of 15 to 20 exposures, 12-15 seconds for "The Ring Nebula", and 5 seconds each for the globular cluster. (After more experimentation, we have posted a second version made from the same raw data, with further image processing, contrast enhancement, and sharpening, done on 06-12-2006.) The Mars image is a composite of 15 images, around 1/15th second, with edge enhancement added after exposure no. 8. All images were further processed and optimized before being cropped and rescaled. |
Improved registration, done from original 2005 data in June, 2006.
Further Speculations:
After considering the results of our admittedly rough and crude first attempts using the DSI to get two deep-sky objects in the light-polluted sky of middle-San Jose, Charles and Stephen decided that the FOV of the images results in an incorrect impression by the viewer, one that is all wrong: similar to the overmagnification that one would attain if trying to look at them with, say, 600x! Thus, the objects are way too large, causing an apparent fuzziness that makes the images seem exceptionally coarse. This was predominantly the result of using a telescope with a focal length of 2800 millimeters and a focal ratio of f/10. So, we did a quick graphical editing job and placed the images inside the artificial field of an ocular. Unfortunately the original data taken for the pictures of M56 and 57 are narrow-field and did not include all the stars in an area of 30 to 60 arcseconds around the objects; so bear with us and imagine in our simulations, below, that the faint field stars are there. Thus, we attempt to show how the Messier objects and planet Mars might really appear in eyepiece views: M57 at about 71x, the lowest power available with Stephen's C-11 with its supplied 40mm eyepiece; M56 and Mars at about 250x. We had to adjust the contrast to reduce the brightness to what one might perceive visually, and to reduce the enhanced color of our digitized Mars so that it was paler and less distinctly orange. Now the images seem less grotesquely out of proportion. What do you think?
We certainly don't propose that all astronomical images should be altered to seem "realistic" relative to telescopic eye views, but offer this experiment as a kind of trick in order to save your pictures if you think they don't stand up to scrutiny at actual original pixel size: make them smaller and they may seem much nicer!
Eyepiece Simulations:|
As I recuperated, I thought more and more about the opportunity to capture something lasting, and found that so too were the thoughts running through my friend Charlie's mind. He had just acquired a 6" aperture Orion Maksutov-Cassegrain and a Celestron goto German equatorial mount, but the rig wasn't ready for prime time. His attempt to image the planet on 29 October with his Meade LPI yielded a picture that he says isn't much better than the ones I've listed above; so he hasn't sent it to me -- yet! So, for one last good try, Charlie and I rendezvoused in my driveway just after the last trick-or-treaters had packed in their goodies and stuffed tummies, leaving my property free from curious, sticky hands. The preferred webcam, used by the Mars imaging experts, is a discontinued Philips ToUCam, but one could not be had easily for this experiment. On Monday afternoon I had located a reasonable alternative: a Logitech "Quickcam" Zoom, for a mere $32 in its full commercial package, at Surplus Computers in Sunnyvale. This unit features a CCD chip that has a resolution of 640x480 pixels and a control panel that allows one to turn off automatic imaging mode, an absolutely necessary requirement for getting the gain in the correct range. To set it up properly, the thing should be modified, the optics removed and a proper attachment added to fit into a telescope focuser (as described in this article by Geoff Chester of the US Naval Observatory.) The Quickcam proved incredibly easy to install, and took nice "daytime" images (as illustrated by its own 'self-portrait' made by me, holding up a mirror.) But without modifications, it was extremely difficult to mate it successfully to a telescope. Late-afternoon experiments with my Orion ST-80 refractor showed the placement, and the eyepieces necessary for a reasonable image scale. With the C-11, it was necessary to use the "zoom" function to increase the image scale, and to employ a 7.5 mm ocular with long eye relief (for a resulting focal ratio that I roughly calculate to be about f/50 to f/60, estimating the approximate distance from the ocular to the CCD chip.) My first trials on the C-11 were dismal: a mere bright yellow featureless blob. But ten minutes of fiddling with the control sliders gradually brought the delicate details into clarity, and even a quick snapshot looked promising. But after trying to stack a series of images with the software program "Registax 2" and to improve the contrast and sharpness by processing, the result was distinctly disappointing, so an urgent call to Charlie persuaded him to bring over the Meade LPI. The improvement yielded by using this, instead of the webcam, was astounding! Even a raw image had detail that surpassed what could be seen by eye. Three careful series were captured, about 25 to 28 pictures each, and the second of the trio was selected for final processing, as the adjustment of focusing and contrast seemed slightly superior. The final processing, done at 2 AM in my chilly garage, yielded this picture: using the C-11 with 3x Orion Barlow, 28 individual 1/50th second exposures, with a slight edge enhancement added after the 5th picture, registered and stacked by means of the Meade Autostar software package. A slight amount of unsharp masking was applied to the composite, plus careful tweaking of the contrast to yield as much latest detail as possible. After comparing this with a number of recent amateur images, I decided that I had not done enough processing. What latent image details were buried in the data? Using "PhotoStudio", an image processing program that had been supplied free with my scanner, I created two image layers, one having the color image (above) and one that contained the monochrome data, heavily edge- and contrast- enhanced. By adjusting the balance between the two visible layers, and then applying even more processing -- and scaling the image a bit larger in size -- I could see that I was beginning to make the picture more like the detailed amateur images, such as those by Dr. Clay P. Sherrod. So, I went a bit further, resampling the image to increase the size while multiplying the number of pixels; reprocessing; then shrinking to a size that was even larger than the previous image. The smooth, bland markings began to take on some depth and irregularity (but, was it a spurious effect?) I confess that the end results seem just a bit strange. The images have a certain odd quality not unlike some of the eyepiece drawings of Percival Lowell, with too much smoothing and stylization to seem absolutely realistic. And because of the enhancement of contrast, Mars no longer looks like the bright shimmering orb one could see at the telescope. A reminiscence, yes; but not a "real" one. It is more like an over-glamorized oversimplification, especially when compared with pictures taken by other amateurs with better equipment and more advanced skills, from the "Marswatch" website. Update, 3 November: After showing this image to Charlie (as well as Ken Sablinsky, the manager of the Orion Telescope Center store in Cupertino, who has taken a superb 'webcam' image of Mars, showing more realism than mine) I decided to scrap my processed version and try again. I took the composited LPI picture, split it into several modes (B&W, with various levels of enhancement of contrast and edge detail, and color renderings) and layered them together again. The intent was to eliminate the coarseness of the previous processing, and though the photo is not nearly as garish and ghastly, hitting you in the face with the boldness of the dark markings, it is a bit more realistic, though very soft compared to the images by experts. So, what do you think of this result? Too big? Would you prefer a slightly smaller scale image? Update, 19 December: While looking around the web for Mars images, I was so discouraged by one that was done with a 'lowly' 105mm aperture Maksutov, which fairly "blew away" mine, that I decided to emulate the creator's particular type of image processing using Regitax 3. Yes: it made a difference, and stacking 22 images acquired with my C-11 on Hallowe'en night, I obtained this result. I suspect that some of the contrast and shading is, however, "manufactured detail", not really an honest depiction of the boundary and color difference regions but so amplified, stretched, and exaggerated by the software as to be phony. Oh, well: if true, then it's merely just one more example of any number of amateur planetary images that have been overprocessed in a vain attempt to give them a "wow factor". Nevertheless, even my odd-looking picture is an 'image to die for' if considered from the viewpoint of, say, 1986. For instance: in that year, my friend Ron Wood tried to photograph Mars with his 8" Newtonian, using Kodak Gold 400 film; and after several exposures the best he came up with was this snapshot; yet his deep-sky photos with the same equipment tended to be spectacular. So, the amateur digital imaging revolution marches forward! The Images:
USB-Struggle Update, 18 January 2006: As explained above, we had nothing but trouble and intermittent performance on our PCs running with Windows versions earlier than XP, while trying to connect and activate the Meade DSI, and even a small amount of trouble with the LSI. Various fixes have been suggested, including the use of a powered USB hub to supply a more reliable current source, closer to the imager and not drawing current from the PC's own USB port. So, we tried a USB 1.0 hub that worked correctly in our office computer. It failed to connect. Our office machine had a different brand of USB card, so we tried to upgrade the garage machine with similar hardware. But, no go. WHAT is so unreliable about USB under Windows 98SE or ME? One time, a device will connect, intialize, and function; yet on another occasion, it won't. Further experimentation with a variety of USB devices -- mouse, scanner, digital camera -- tended to suggest that the USB 2.0 card we had installed was not reliable. All we could do was to buy another one, with different chipset, and try again. Finally after two failures, our third card worked. It is a "USB Turbo 2.0" by ADS Tech, model USBX-2000, sold by MicroCenter in early 2006 for $16.99. It has a CDRom containing an installation program with drivers for Win 98SE, ME, 2000, and XP; and for Mac OS X on Mac GS300 or later. The card worked properly immediately. And it recognized our Logitech webcam right away. But, when we hooked a USB 2.0 powered hub to it, the problems began. The hub relied on Windows to supply a driver, and Windows seems to have taken three full cold reboot cycles to complete the process of registering it! So, to get the hub to work, we had to open and close the OS and wait and wait and wait...the hourglass appears on the screen, various dialogue boxes open and close...it seems interminable. Finally, perhaps ten or twelve minutes later, the hub was recognized! BUT...now it would not work with the Logitech webcam! That required TWO MORE complete reboot cycles. Now, we're into some time-wasting! In the background, we listened to the entirety of the Rachmaninoff Piano Concerto No. 3, followed by the Concerto No. 4 by Anton Rubinstein. And we STILL were not finished. At last, Windows ME came up, recognizing the powered hub and the Logitech webcam. We took a picture. We cheered and danced around the garage in glee, to the finale of the Rubinstein piano concerto. NOW: the final test. Our hands shook a little as we connected our twenty-foot USB 2 extension cord to the back of the PC, and into the powered hub. We rebooted the computer. NADA. Nothing happened except the opening of the Windows desktop. The Logitech webcam would not initialize, even though the power light on the camera was bright green, and the lights on the hub glowed properly. We told Windows to shut down. Instantly, a dialogue box opened up, and we got a quick glimpse of a message that Windows was searching for a device. NOW? Too late? While Windows is shutting OFF? How ridiculous! But we went through the shut-down; powered off the PC; and tried to reboot. To condense this story a bit, it took FIVE SUCCESSIVE OFF/ON COLD REBOOTS of Windows ME before the hub recognized the Logitech webcam. Now, we had finished playing Beethoven's Emperor Concerto and were getting sick of piano concerti... The picture that the author took at this very moment shows his elation. Now, the next step will be to see if we can operate the Meade DSI at the end of the USB extension cord, through the powered hub. Update: I just discovered this interesting sequence of pictures done by well known Toronto amateur astronomer Paul Markov, showing his progress with a Logitech QuickCam 4000 and the Meade DSI Pro digital imager on an alt-az mounted Meade LX200 GPS scope, posted on his 2005 observing logbook (relevant entries being Feb. 4, 13, Mar. 26, June 24, Jul. 23, Aug. 6-7, Sep. 3, and Oct. 1) and his 2006 observing logbook (look for the entries for Jan. 20, Apr. 8, 19, 28, etc.) His progress is quite remarkable, culminating in a very detailed "Crab" nebula, with filaments clearly recorded -- during a full moon! -- and a beautiful color M27. -- 3/29/07 |
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Friday 15 December 2006 at 12:55 pm; last edited on Monday 4 February 2008 at 11:12 am.
Stephen sometimes has trouble getting to the telescope,
since the animals don't much care for astronomy
but DO like listening to shortwave --
or looking at "Pet of the Day" on the net.
