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.

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