Wednesday, August 2, 2017

Three nights

Last weekend I was able to observe, and photograph the moon on three consecutive nights with the 8-inch Celestron Edge HD telescope at home on my driveway. As before I simply connected my Nikon F3HP camera body to the rear cell of the telescope with a "T-adapter" and "T-ring" for Nikon cameras. In so doing, I turned the telescope into a 2000mm F/10 telephoto lens. The film was again Fujicolor 200 color negative film and I exposed it with shutter speeds from 1/250th to 1/8th of a second. From examination of the processed film, it seems the best exposures were at 1/60th second or so. To suppress vibration that would otherwise blur the photos, I manually raised the camera's mirror that flips out of the way of the shutter before it operates and tripped the shutter using the self timer. Again, vibration suppression pads were used under the tripod's feet.
The result you see here is a montage of the three photos I took over three nights. I focused the telescope, exposed a series of frames with the mirror locked up, then unlocked the mirror and refocused the telescope before exposing another series of frames. I repeated this process until the entire roll was exposed. In this way, I maximized the chances of getting perfectly focused negatives. Before taking this pictures, I bought a replacement focusing screen more suited to this kind of work than the standard "K" type screen Nikon cameras such at the F-3 came with. I found a "D" type screen which is simply entirely an entirely fine matte screen without any micro-prism or split image array. It's made for very long focal length telephoto lenses and thus well suited to the Celestron since Nikon did make a 2,000mm mirror lens in the past. It did make getting exact focus easier but I think for dimmer objects I'll either need to buy a Beattie Intenscreen or find a DW-4 finder for my Nikon that magnifies the image by six times. For now, the focusing screen I bought will do.
After scanning a frame from each roll of film at a resolution of 3,200 dpi, I imported the files into Adobe Photoshop and created this montage after adjusting the brightness levels, color balance and lightly sharpening them. As you can see, the changes of illumination across the lunar surface are quite dramatic over three days.

Saturday, July 29, 2017

Another success with my 35mm camera........

 Two weeks ago I imaged the moon with my webcam imager and my Nikon F3HP 35mm camera. Several days ago I picked up the processed film and found that most if not all the negatives are in at least acceptable focus, and a good many were well exposed. As before, I used Fujicolor 200 color negative film and exposure times from 1/250th to 1/15th of a second. To suppress vibration, I used vibration suppression pads under the feet of the tripod, and I used the mirror lockup my camera is equipped with. I then used the self time to trip the shutter to avoid vibration from my hand touching the camera.
Once I found a suitable negative, I scanned it with my Canon LIDE 700 flatbed scanner, which also comes with a film strip adapter. This scanner is not ideal for scanning film, but it is adequate for occasional use in that way. After initial scanning, I imported it into Adobe Photoshop then adjusted the levels, brightness, contrast and color balance. I also lightly sharpened it. Before scanning the film, I checked the calibration which eliminated the odd magenta tint that had appeared in the last photo. This picture is a full frame image of the original negative. As you can see, with a focal length of just over 2,000mm, the moon occupies a large portion of a 35mm film frame. Eventually, I plan to photograph the moon on film through an entire cycle of it's phases. It will take a year or so to do that given the interference from weather, work and other considerations that come first.

Sunday, July 23, 2017

Two visitors from deep space

While I have been spending time familiarizing myself with the 8-inch Celestron EdgeHD Schmidt Cassegrain I recently bought and taking photos with it, I've also been observing with my 15-inch Dobsonian last week at the local club's dark sky site. Normally, it's cloudy and murky here during the summer, but windows do open in the weather of good conditions for observing faint objects from time to time. While I observed the usual Messier, NGC and IC objects that are prominent in the summer skies, I stopped to take a look at two icy visitors to the inner Solar System that are observable right now as soon as the skies are fully dark. They are the long period comet C/2015 V2 Johnson and the periodic comet 71P/Clark.
C/2015 V2 Johnson is a long period comet that has been on the scene for months now, and now it's on it's way back into the frigid, dark outer reaches of the Solar System. Discovered by Jess Johnson of the Catalina Sky Survey, this comet is escaping the Solar System on a hyperbolic trajectory forever after reaching perihelion last June. It's original orbit had an aphelia of about 59,000 astronomical units or nearly a light year away from the Sun, but gravitational perturbations from the giant planets have accelerated it to Solar escape velocity. Through my 15-inch at 227X, it appeared as an elongated object of about eighth magnitude with a bright inner core. Right now C/2015 V2 Johnson in Virgo, soon to be lost in the twilight then daytime skies. It's soon to be a very faint object for large telescopes only, so if you wish to see this comet, take any opportunities available now since it will never return.

The periodic comet 71P/Clark on the other hand has been seen on a number of occasions since it's discovery in 1973 by Michael Clark at the Mt. John University Observatory. This periodic visitor has an orbital period of 5.5 years, an orbital inclination of 9.5 degrees and an eccentricity of .499. That places perihelion at 1.56 A.U., or just outside the orbit of Mars, and aphelion at 4.68 A.U. which brings it close to but not across Jupiter's orbit. It is therefore under Jupiter's gravitational spell. It has been observed at every apparition since it's discovery. Through the 15-inch at 227X, it looked more like a remote and faint galaxy or globular cluster than a comet. It had a round, diffuse appearance with a very weak central brightening, it was a little difficult to see due to the light pollution that pervades the Gulf Coast. This comet is impossible for small telescopes or anyone in badly light polluted areas, therefore plan to look for 71P/Clark in Scorpius from at least a reasonably dark area and an 8-inch or larger telescope. The comet just passed through perihelion three weeks ago, and is now fading quickly. The next appearance of 71P/Clark will be in 2023.

Friday, July 21, 2017

The last quarter moon

Last week, I set up the Celestron to image the last quarter moon at some of the same places I imaged it two weeks before as well as new locations I have not imaged yet. The images below are the result, using the same camera and Barlow lens, which I am probably going to be upgrading soon. There seems to be a color fringing problem that originates with the Barlow lens, it's most definitely not the telescope itself. They can introduce chromatic and spherical aberrations, which the EdgeHD telescopes otherwise stamp out completely. I'll have to purchase some top shelf Barlow lenses to cure this defect, and even at that the atmosphere can also introduce color fringing because it acts like a weak prism. The only remedy for that is imaging when the moon or planet are as high in the sky as possible.
The Straight Wall or Rupes Recta is an immense thrust fault formed when the surface to the left of this feature dropped downwards relative to the ground to the right. Contrary to the namesake, it's not a vertical cliff, scarp or even a steep slope. The actual slope is about ten degrees, which people can walk up to the top easily over its 1,300 foot height and sixty five mile length. To an astronaut on the ground, it would look like a high hill that extends to both sides as far as he or she could see. To the right is a rille that formed when a lava tube collapses or the ground drops between parallel faults in the lunar crust. When the Sun angle at the site is low, both features are easy to see near the moon's first and last quarter phases through a small telescope. At first quarter, the straight wall is visible as a black line, at third quarter the Straight Wall's steeper face is illuminated and appears white. At other times it's very hard to impossible to see.
Rima Hyginus is an immense rille formed by faulting and collapse of the overlying rock and large scale volcanic eruptions, including fire fountains and pyroclastic flows. The pits along it's length are not impact craters, they are volcanic vents and collapse pits where a large dike channeled magma from the lunar mantle to the surface. From there the lavas spread out over the surround area. The largest pit Hyginus is a caldera. Between Rima Hyginus and the crater Triesnecker are the numerous but much shallower and smaller Triesnecker riles, which cover the lava plains like a fracture pattern in a window across Sinus Medii. They are not related to the crater Triesnecker, but instead are related to the deposition of the mare lavas that formed Sinus Medii. These are likely of tectonic origin.

Near this large and nearly buried by lava flows carter is the strange impact feature known as Davy Catena, a line of small impact craters that formed at the same time. It's thought a small asteroid or comet was disrupted by the Earth's or Moon's gravity before the fragments plowed into the Moon. The impacts occurred after the lavas invaded the region then hardened as evidenced by their fresh appearance, along with most of the other smaller craters in the region.

Near the moon's south pole the surface is entirely composed of lighter aluminum rich rock and is saturated with craters. In other words, the formation of a crater destroys one or more craters already there. Here the large crater Clavius dominates the scene near the center of the photo, with the younger and smaller crater Tycho at the top center. The immense heat of the impacts that formed the larger crater left pools of impact melt that hardened into a smooth crater floor before being crater by smaller and less numerous impactors. Clavius itself has an arc of smaller crater of decreasing size across it's floor while the much younger crater Tycho still has an impressive series of rays extending from it. It was formed about 107 million years ago by an asteroid or comet striking the moon. The 56-mile wide crater has a central peak two miles high in the center that was pushed up by the rebound of the Moon's crust during the impact that created Tycho. Photographs from the Lunar Reconnaissance Orbiter show a 120-foot wide boulder resting on the summit of Tycho's central peak.

The 50-mile wide crater Archimedes lies in Mare Imbrium with the nearby smaller and younger craters Autolycus and Aristillus. After the impact that formed Archimedes but before the impacts that formed the other craters, the lavas that formed Mare Imbrium invaded and flooded the crater floor from below and the surrounding plain. By the time Autolycus and Aristillus formed, Mare Imbrium has solidified into a vast plain of dark basaltic rock. Despite the flooding of the crater by lava, the rim towers over two miles above the lava that forms the present crater floor. Consequently there is a flat crater floor under which the central peak and original crater floor is now buried under lava flows. Luna 2, the first probe to reach the moon crashed into it between the crater Archimedes and Autolycus.
In general, l had a successful run of imaging that lasted until dawn was underway. However, I will clearly need to upgrade the way I'm increasing the magnification to get these lunar close ups and planetary photos. That requires better Barlow lenses, one of which with greater magnification than the 2.8X University Optics Barlow I am using now. When the seeing is very good, I clearly could use a 4X or even 5X to get all the detail I can. That will require careful polar alignment because any error will cause the moon to drift as the telescope tracks. That will make close up imagery much harder, even with stacking video frames. All of these pictures were 75 frames stacked from 20 second AVI video files taken the week before. With the coming favorable apparition of Mars, I'll want to be ready to image this challenging planet before it's out of view for another eighteen months.

Wednesday, July 12, 2017

Success at last!

After a semi-successful beginning, I succeeded in getting a sharp picture of the entire moon with my Nikon F3HP camera. I tried using a Bahtinov mask to focus on the bright star Antares, which was nearby, and fired off a series of exposures using the mirror lock up and the self-timer to prevent mirror slap and vibration. That could have blurred the photos. I found the mask not to be as helpful as I expected, thus I am looking into obtaining a replacement focusing screen for my camera appropriate for astronomical photography. So I then refocused carefully without it, and took another series of exposures which ranged from 1/250th to 1/15th of a second to ensure one or two would be well exposed, but not too over or underexposed to be useable. I then refocused again and exposed another series of frames until the entire roll was exposed to assure at least one or two negatives would be in focus. That was the error I made last time, I thought I had got the moon in focus when in fact I hadn't, thus all of the negatives were blurred.
To couple the camera to the telescope, I simply used a T-adapter and T-ring for my Nikon to connect it directly to the rear cell of the telescope. I then took the film to a local photo lab for processing. After scanning, I used Adobe Photoshop to adjust the levels, resolution, image size, color balance and contrast before sharpening the image a little. The negatives are of good enough quality to make prints on photographic paper. Now that I can get sharp, well exposed shots of the whole moon, I will start taking photos of it through the whole lunar cycle. I'll also be able to do the same thing with the Sun, for which I now have an over the aperture solar filter on the way. A total solar eclipse is going to take place in the U.S. on the 21rst of August, and weather willing I'll be able to photograph it. For now, the Sun's very quiet magnetically, so few sunspots are visible on it now. When and if sunspots increase in number, I'll be photographing the Sun too.

Saturday, July 8, 2017

More images taken through the Celestron

During the holiday weekend, I set up the Celestron and proceeded to start taking 30-second AVI video files of the moon, Jupiter and Saturn with the video eyepiece for later processing. I then imported them into Registax 6, and extracted these still images from them. I have been learning how to use the features of Registax then Photoshop to suppress noise and get as sharp a picture as possible with a limited capability camera.
The crater Eratosthenes, lunar Apennines and crater Archimedes.
Saturn and it's rings.

The lunar north polar region, the crater Plato and the Alpine Valley.

Close up of the Alpine Valley.

Close up of the crater Clavius.

The Straight Wall and its surroundings.

The planet Jupiter and the Great Red Spot.

Close up of the crater Eratosthenes and lunar Apennines'.

Close up of the crater Tycho and its central peak.

Lunar terminator with the craters Clavius and Tycho.
Close up of the crater Plato.
The extreme close ups of the moon and the images of the planets were made in the same way, by placing a 2.8X University Optics Barlow lens between the telescope and the camera to stretch the focal length to nearly 6,000mm. The wider area images of the moon were made by directly coupling the camera to the telescope's visual back.That gave the required image scale for closes ups of lunar craters and the planets while the image remained relatively sharp in spite of the turbulence in the atmosphere overhead. The seeing was good, but not excellent. As for the color fringing I noted, it's not due to the Barlow lens of the optics, it's refraction caused by the atmosphere and the low altitudes of the moon, Jupiter and Saturn that are the norm during the summer. I have been able to partially remove that with Registax 6, but not entirely. However, I am very pleased with what I have been able to achieve thus far, especially with the close ups of the lunar craters and other lunar features such as the Straight Wall. I will keep working with this camera until I can find a better one, possibly a camera that can be used for both planetary and deep sky objects.

Sunday, July 2, 2017

Some early results with a "video eyepiece" and my very old Nikon film camera

Now that the Fourth of July holiday weekend is underway, and I now have a polar alignment scope and dew heater controller, it's time to begin mastering this optical and mechanical marvel known as a Celestron EdgeHD Schmidt-Cassegrain and an AVX mount. I have been practicing getting good polar and GOTO alignments, and learning how to use the All Star Polar Alignment feature in the hand controller. I have been able to get a star to stay still for half an hour, and just tonight I got the polar alignment scope roughly calibrated, then a decent polar alignment with is right afterwards.

At the same time, I was trying the telescope out with my inexpensive video eyepiece on the Moon, Jupiter and Saturn. I'm also starting to learn the intricacies of a nifty free program called Registax6. It extracts frames from the AVI video files, aligns them, and stacks them to form a still image that can be sharpened enormously BEFORE you import it into a photo editing program such as Photoshop. The results I have achieved so far include the work below.

The photo of Saturn was made with a 2.8X Barlow lens, but all of the lunar photos were taken at prime focus. In other words, I simply used the telescope as a giant telephoto lens. I'm sure I could indeed photograph VERY distant subjects during the day time with this telescope, but turbulence would blur the photos.

 I achieved much more success so far than I was ever able to with my old Meade model 628 6-inch Newtonian and equatorial mount and my camera. I wasted whole rolls of film because finding objects and focusing the camera were VERY hard, I got the exposure time wrong, the polar alignment was WAY OFF or some other glitch scuttled my photos. It was wonderful to see the result as soon as I finished recording the video on my lap top. However, these pictures also show I will have to get a much better camera and among other things, a flip mirror and filter wheel. The limitations are obvious, especially when I was trying to image Saturn. It's faint and quite hard for the camera to record it well. I would also like to be able to record video of deep sky objects or take still images at some point.
However, I will be using my film camera, which is a Nikon F-3HP that I had for over 25 years. It's was a top of the line camera when it was introduced back in 1980, and still is today as far as 35mm film cameras are concerned. I have a T adapter that make connecting my camera to the telescope simple and allows me to use it as a 2,000 mm F/10 telephoto lens. That is how the last picture was taken, using Fujicolor 200 color print film. I found focusing the camera difficult, and to address that I got a Bathitnov mask, but it appears a clear focusing screen is needed, or a flip mirror. The photo wasn't as sharp as it should have been, but aggressive use of un-sharp masking and careful scanning of the film made a presentable picture possible. The photo is of the entire frame, not cropped.
I am used to the simplicity and quick set up of Dobsonians, and I won't be retiring them any time soon. They beat the EdgeHD SCT handily in terms of light gathering power and resolution. My 15-inch Dob easily shows objects that simply cannot be seen through any 8-inch telescope at the same site. However, the SCT has very good image quality. Combine that with a mounting that is stable and has excellent pointing accuracy once you align it correctly, this telescope is a very good choice for an all around telescope. For someone who wants a GOTO telescope that can be used for imaging at a later date, in a package that will fit in any car and is easy to set up, an 8-inch Celestron EdgeHD SCT is a telescope you should consider. If I was starting out in astronomy today, I would have wanted this telescope for my first telescope, even though I would have had a lot to learn along the way.