Wednesday, January 2, 2013

Fun With Telescopes!

Like many amateur astronomers, I've got more than a couple telescopes.  Most are better at some tasks than others.  Some get used a lot, others seem to get passed by.  This post is about a 4.5" (11cm) apochromatic (APO) refractor that for various reasons, isn't used very often.  More often I grab the smaller 80mm F/6 APO that has taken multitudes of pics for this blog...  Shown at right, the 11cm William Optics version has a great focuser, but the longer focal length makes it very sensitive to vibration - likely one cause of my issues with it...  I did use it the other day for the picture of the sun - at right is the "Green Flash" picture taken with the 11cm with 1.4X extender to make it about 1080mm focal length.
That same night, I took a profile shot of Kitt Peak National Observatory from that spot near Milepost 8.5 of the Catalina Highway, then we stopped down near Milepost 3 for another shot.  Taken from the 2 locations about 3 miles across, it is a substantial-enough baseline that I thought they might show some 3-D effect from the nearly 60 mile distant Observatory, even though all the scopes are about the same distance.  Now realize that the two pictures shown here are taken nearly 30 minutes apart, accounting for some of the brightness and color differences...  But I put them together, and sure enough, the stereo effect is quite apparent for the "south ridge" domes and solar telescope at right, as well as the separation of the central ridge of the mountain.  This is a cross-eyed view, as always, cross your eyes slightly to look at the right picture with left eye and left picture with right eye.  The central image will show depth.  Click the image for the full-size view.
The a day earlier I had taken this same telescope up to "A" Mountain to the west side of downtown Tucson, to try a time-lapse sequence of the cranes working on a stadium addition on Campus.  While nearly 3 miles away, the resolution was quite good, though I had to go to some effort to avoid vibration.  I enabled mirror lockup on the camera and also used a 2 second timer to allow vibrations to damp out before the image was taken.  The full frame is shown at left - the telescope again used with the 1.4X extender to lengthen the focal length to 1080mm.  While not extra-ordinary, don't forget these images are compressed a lot for the blog, so I made a full-resolution crop of a frame section at right.  From the nearly 3 miles, the resolution appears to be about 2 inches or so.  Again, this is the same frame, but not reduced in resolution when you click to look at the full frame.  The resolution is quite good, considering that the white building behind the crane is Catalina High School, another 2.5 miles behind, with lots of heat waves seen in the longer distance.
When used without the extender, only the central part of the image is sharp to my fussy eye.  It may be worth my while to invest in a corrector made especially for this telescope to recover the full field.  But with the extender, and pending corrector, it is a scope worthy of more use!

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