Perched atop the roof of the AW Smith building on CWRU’s quad, the 9.5″ Warner and Swasey refractor has been a mainstay of the Department of Astronomy for many years. Originally built in 1894 by Worchester R. Warner and Ambrose Swasey for their backyard observatory, it was donated in 1919 to the Case School of Applied Science when Warner and Swasey funded the construction of the University’s new observatory on Taylor Road in East Cleveland. After years of use at Taylor Road, the telescope ultimately found its current home on CWRU’s main campus in 1986. While bright Cleveland lights make deep sky objects difficult to see from campus, the telescope continues to give excellent views of the sun, moon, and planets. Recently, two CWRU students have used the telescope for a variety of astrophotography projects, and share their experiences here.
When I first walked up the five flights of stairs and out onto the dark roof of the AW Smith building, I had no idea what to expect. My good friend, Brad Odhner (PHYS/ CLSC), was going to be observing that night and invited me along to give astrophotography a try. I was blown away by the size and complexity of the telescope. He showed me how it worked: how the gears functioned, how the telescope automatically corrected for the rotation of the Earth, and how to home in on a specific point in the sky. He then proceeded to show me some stars, Saturn, and the moon. Seeing these objects through the telescope’s eyepiece was breathtaking, and I was excited to give my camera a try.
We removed the telescope’s eyepiece and replaced it with an adaptor made to fit Canon models (I use a Canon t4i DSLR), and just like that the 9.5″ refractor became my lens and the moon became my subject. I was very pleased with how much detail my camera was capturing. Being able to see the craters so clearly thrilled me! I tweaked the telescope’s position to my liking, adjusted the camera’s settings and snapped the picture. The resulting image instantly became one of my favorite photos. The fact that I was able to capture such a detailed image of the moon still amazes me, and I plan on using the telescope several more times before I graduate.- Eric
My favorite part about using the Warner and Swasey refractor is the sense of accomplishment that comes from locating a distant celestial object by manually pointing the large telescope in its general direction and searching around for it. So far, the faintest thing I’ve managed to observe is Uranus. Even though it appeared rather dim and featureless, it clearly wasn’t a star, and I was very excited to find something I couldn’t see with the naked eye. I was taking a photography class on black and white film techniques. Since there’s a lens mount adapter in the observatory dome, I thought I’d use the telescope as a giant lens for my little 35mm camera and try my hand at astrophotography. Unfortunately, the Cleveland light pollution washes out most Messier objects, and the planets don’t appear big enough to yield a sharp image. So I pointed the Warner and Swasey refractor at the moon.
One basic guideline for making correct exposures in manual photography is the ‘sunny 16 rule,’ which recommends a shutter speed equal to the reciprocal of the film speed at an aperture of f/16 for subjects in direct sunlight. As the full moon is, after all, a subject in direct sunlight, I used this as a starting point for the target exposure value. The moon has a low albedo, and some light is scattered in the atmosphere, so I figured I would need a longer exposure than indicated by the guideline. Since I was estimating the telescope’s aperture, I made several exposures across a wide range of shutter speeds to increase my chances of obtaining a good image. After I developed the roll of film, I made a 5″x7″ print from the best exposure, raising the contrast to emphasize the maria and craters. – Blaise
The Warner and Swasey 9.5″ refractor is available for use by all CWRU faculty, staff, and students. Contact Charles Knox for more information. This story originally appeared in the 2016 Department of Astronomy newsletter.