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.