Thursday, May 30, 2013

Planetary trio in the western sky


For the past several days, the planets Mercury, Venus and Jupiter have gathered together into a small region of sky. Through my 6-inch F/8 Dobsonian telescope, Mercury looked like a tiny, featureless gibbous moon with an orange tint. Venus was a tiny round, yellow-white disk. Jupiter showed it's oval shape, equatorial belts and Galilean moons. At 109X the poor seeing was evident, as was a prismatic color effect caused by refraction from their light passing through our atmosphere. It was beautiful and at the same time a good demonstration of why billions have been spent building space telescopes.

The next night I opted to photograph this conjunction which widened dramatically over 24 hours. I used my old Nikon F-3HP, a Leitz Tiltall tripod and 55, 85, 135 and 180mm lenses to take the pictures you see here. I used 200 speed Fujicolor film for color prints, exposing it for up to eight full seconds in the deepening twilight with the lens stopped down at first. A cable release was used to avoid jiggling the camera and blurring the images. Even though the camera's internal light meter was able to read the dimming scene, I bracketed my exposures to be assured at least a few will be correctly exposed. When it was nearly fully dark, I used f/stops ranging from wide open at F/2.8 to F/5.6. I used long exposure times because I wanted to record passing vehicles on the I-10 Bayway as white and red streaks. The location I used to photograph this event was a parking lot overlooking Mobile Bay, and the I-10 Bayway with the city of Mobile Alabama in the distance.

Once I had exposed film in hand, I took it to a local photography supply center for processing. I then scanned the negatives with a Canon Canoscan LIDE700F flatbed scanner that can also scan unmounted film at very high resolution. It is not ideal for those who must scan large numbers of 35mm negatives and transparencies on a daily basis, but it is well suited for those who mainly need to scan documents, photos and the occasional negative. It is a USB scanner that can also be used to copy and print documents if a printer is also connected to the computer. Conjunctions like this one are always nice to watch, they offer the chance to see two, three or even more planets in one session.

No comments: