This is a sequence of seven images of the lunar eclipse of this past October 27th.  It was done on one frame of film (remember film?), not a composite assembled in Photoshop.  I wanted to capture the Earth's shadow. It ended up requiring more planning than I thought it would.

    I used an Olympus OM1, and since it doesn't have a provision for taking multiple exposures on one frame, I had to lock the shutter open on bulb, and use the lens cap as the shutter.  I actually bought a lens with this project in mind.  It's a cheap 500mm f/8 mirror lens (a Mak-Cass).  Since it can't be stopped down with an iris, I had to make an off-axis mask with a small 7.5mm hole.  This brings it to f/80.  Without this, there's no way I could have done a manual "hat trick" exposure fast enough for the partial phases. It was removed for the 3 images during totality.  While experimenting though, I discovered that this mask caused severe vignetting.  A full quarter of the field on the side opposite the hole was completely dark.  So I had to plan out where to orient the hole for the beginning and end of the eclipse.

    I used Starry Night Pro to help me plan out the framing.  I decided to orient the camera equatorially as close as possible.  That is, North is up and East is left.  The moon moved through the field from lower right to upper left.  I set the field of view in the program to approximate the true field of the camera lens.  I even looked at the screen through the camera to see where the first image should start.  I had the program run an animation of the event to be sure the whole event would fit in the field of the camera, and to decide at what times I wanted to take the images.  I decided on every 36 minutes, centered on mid-eclipse.

    This animation showed me another challenge.  It shows outlines of the Earth's umbra and penumbra.  The shadow moves!  And not just by the same amount the sun moves around the ecliptic.  It would if we were at the North Pole or at the center of the Earth, but since we're on a surface that moves relative to the Earth-moon line, the parallax changes.  A whole moon diameter's worth during the 3+ hours of the sequence I shot.

    The camera rode piggy-back on my 4 1/2" Newtonian on an Orion EQ3 mount. I used the scope for guiding.  But now I've discovered that I can't just find a guide star and sit on it all night.  If I did that, the picture would come out distorted, with the images pushed together and partial phase images showing curved umbra edges that don't line up on a common circle.  The program showed me that during each 36 minute interval, the shadow moves 4.5 arc-minutes West and about 1 arc-minute North.  So I had to move the camera and guide scope by the same amount.  I have a guiding eyepiece with an illuminated reticle.  It's also adjustable so that the reticle can be moved to a guide star instead of having to move the whole guide scope.  I used this feature to help move the scope.

    Eclipse night was supposed to be a little clearer than it ended up.  I went to Batsto, NJ where a few WAS members were headed.  I decided on this spot for its horizons, lack of distractions and based on a satellite image, better weather prospects.  It turned out to make a difference since we were right on the edge of the cloud line most of the night.  And the lack of heavy light pollution didn't hurt.

    I got there with about 3 hours to set up.  It turned out I need most of that.  Set up the tripod, assemble the scope and camera, wait for it to get dark to do a polar alignment, wait for clouds to pass, critically focus the camera and tape it down, wait for the guide star to rise and more clouds to clear, orient the camera body, frame the moon right, re-acquire and center the guide star, eat another donut.  It all adds up.

    I started by positioning the guide star and reticle all the way over on the West side of its adjustment, and then centered the star.  Just before the first exposure, I moved the scope East and South the required amount, took the first shot, then moved the scope back to center the star in the reticle, and then waited there for the second shot.   This saves reticle travel.  I figured out that if I turn off the drive and let the stars drift, 4.5 arc-minutes of sky goes by in about 18 seconds.  Holding the 2X button on my controller for 18 seconds moved the scope West the right amount, and holding it 4 seconds showed me how far to move it in declination.

    I was worried that I might run out of reticle travel before I was done, so I used the Pleiades to guide.  I figured that if I did run out of travel, I could just move the reticle to another star.  It turns out I had just enough, but I did need the brightness of these stars when the clouds were around.  Fortunately they were usually thin.  As you can see in the last image, the clouds were thicker and I totally lost the guide star for that one.  I just had to trust that it hadn't drifted since I'd moved it after the previous exposure.

    I had to increase some exposure times to compensate for thin clouds.  I just had to guess, but it didn't hurt having Jerry Lodriguss set up right next to me shooting digital. He was able to show me instant results from bracketed exposures to give me an idea.  Exposure times ended up as follows.  1/10 sec. at f/80, 1/2 sec. at f/80, 8 sec. at f/8 through thin clouds, 35 sec. at f/8 through thicker clouds, 3 sec. at f/8, 1/2 sec. at f/80 through thin clouds, and 1/4 sec. at f/80 through broken thick clouds.  I used a table done by Fred Espenak as a guide to plan exposure times, but I had to be flexible.

    I was amazed it came out as good as it did.  We've been lucky to have 2 total lunar eclipses in the last 2 years visible in their entirety above our horizon.  I'm glad I got something good out of it.  At first that final image bothered me, but now I think I like it.  It adds realism and serves as a reminder of what it took to get the shot and how close I came to missing it.  Just after that last shot, we lost the moon completely to the clouds for the next couple hours.

    Maybe I'll just sit back and watch the next one.

- Scott Ewart