Friday, August 25, 2017

The 2017 Solar Eclipse

The day millions waited for years to come has arrived last Monday, and I was ready to observe and photograph the 2017 Solar Eclipse. While it was not total from my area, it was an 85 percent partial eclipse well worth the wait.
To take this photo, I used the same telescope, camera and film used for the whole disk pictures of the moon published here. Because I was photographing the Sun, an over the aperture solar filter was required. I considered opting for a glass filter, but instead bought a Baader safety film Mylar filter instead. It left the Sun with a bluish or violet cast but the image quality was excellent. The views are razor sharp and irregularities in the moon's limb were obvious at 64X through a 32mm Orion Optiluxe eyepiece and a 2-inch Highpoint mirror star diagonal. Even the photos show the rice like texture of the granulated photosphere of the Sun.
I shot a series of pictures with the mirror locked up, and the self timer used to eliminate vibration. Exposure times ranged from 1/2000th of a second to 1/125th of a second, with the best exposures being at 1/500th of a second. The sky darkened dramatically and the temperature fell noticeably. Shadows took on a peculiar sharp edge quality and though eclipse glasses the Sun was easy to see as a thin crescent.
I set up at a local school system's science education center, where the staff was video broadcasting the event and some staffers and students were enjoying the view between the photos I took. I mainly wanted to observe the eclipse visually, but I wanted to get a few photos too. Everyone enjoyed the experience and many came away with photos of their own.
I was able to watch the eclipse until about 20 minutes after the eclipse reached it's maximum for my area, before clouds moved in and threatened to douse the telescope in rain. I then dismantled the telescope and took the film to a local lab for immediate processing. I still have to look through the rest of the film and some Solar photos I took as a test the day before the eclipse. Once I scan and process them, they will be posted here.

Monday, August 21, 2017

The Waning Crescent Moon

Four days before the total solar eclipse that crossed my country from one side to the other, the first one to do that in 99 years, I came home from work and set up the Celestron to catch the rising waning crescent moon. After letting the telescope equalize its temperature with the incredibly hot and muggy night air and cleaning up from work, I first browsed some deep sky objects of the fall sky. Then I looked as the moon, and features such as the crater Aristarchus, Schroeter's Valley and Sinus Iridium. Then is was time to take photographs of the 25-day old waning crescent moon.
I used the same film, camera, and technique as the earlier photos, except I used much longer exposure times than I used for the lunar phases near full moon. I started at 1/60h of a second and went as long as two full seconds in an effort to see if I could record the Earthshine on the dark side. While I did get good shots of the sunlit portion of the Moon, apparently two seconds with Fujicolor 200 print film was not enough to clearly record the Earthshine, at least not at F/10. It seems the moon was too bright for it and I needed to expose the film much longer to record it, but a two second exposure blew out the sunlit portion of the moon completely. Even with the frame I scanned here, the moon's limb is bleached out.
I did use the lunar rate on the AVX mount, and it seems to track the moon fine for longer exposures I will be taking in the future. When the next total lunar eclipse comes along, I will be ready. The focusing screen paid big dividends in enabling a sharp focus to be achieved. With the last two frames of film, I took a couple of test exposures of the Double Cluster at F/10 to see how the film would respond to long exposures. A fair number of stars appeared in the second shot, but they were trailed because I forgot to switch back to the sidereal rate and I don't yet have an auto-guider to guide the mount. I'm going to get a focal reducer before I try taking any photos of deep sky objects through the 8-inch EdgeHD, or simply buy a 80mm APO and use that on the AVX mount. It was just a test anyway.
Today was a day I was long looking forward to, and that was the total solar eclipse that took place today. I set up the Celestron at a local school system's science center and when I was not giving folks a look at the deep partial eclipse as it happened, I took some photographs. The day before I photographed the Sun and the sunspot groups across its face. When I get the film back from the lab, I will post it here. It was despite the hot and humid weather, a wonderful time.

Saturday, August 19, 2017

The Twelve Day-Old Moon

The last two weeks were a period of almost nothing but thunder, lightning, strong wind, clouds and torrential rain, but one clear night came along where it was worth the time to set up the Celestron. After setting up and polar-aligning the mounting, it was time to do some visual observing and photography in the driveway. After observing the planets Jupiter and Saturn, and a number of bright deep sky objects, I turned the telescope to the moon. After looking at features of interest to me with a high power eyepiece, I removed the eyepiece and diagonal and replaced it with the Nikon F-3HP and T-Adapter to photograph the moon. At the time it was two days away from full, which ensured faint objects were washed out or invisible due to the moonlight flooding the sky.
As before, Fujicolor 200 color print film was used, and again the camera's mirror was locked up and the self-timer was used to eliminate vibration from the operation of the shutter. Vibration suppression pads under the feet of the tripod were also used. Because the moon was nearly full, I exposed a series of frames using shutter speeds from 1/500th of a second down to 1/15th of a second, which badly overexposed the film. The best negatives were exposed at 1/250th and 1/125th of a second, and after examining the film I scanned one of the negatives at 3,200dpi with my Canon flat-bed scanner which also can scan 35mm film as well. Final processing was done with Abobe Photo Shop, which consisted of minor adjustments to the brightness levels, light sharpening of the image and cropping. The D-screen I bought for the camera made focusing much easier than the stock K screen older Nikon cameras come with. As a result, all of the frames were at least acceptably sharp.

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.