Untitled

The Moon orbits Earth in an elliptical orbit, meaning that its

distance from us varies depending on where it happens to be in its

orbit. Occasionally, the extremes of these distances coincides with a

full Moon. The left image was taken last night (December 16, 2013)

and represents the Moon at its greatest distance from Earth (apogee).

The image on the right was taken on the evening of June 22, 2013 and

represents the Moon at its nearest distance (perigee). Both were

taken using a Canon 5D attached to a Meade ETX90 with a fixed focal

length of 1250mm and a fixed aperture of f/13.8. Your thoughts on

whether or not this is an effective photographic comparison are

appreciated. Also, can you identify any differences between the two

moons besides their apparent size, of course. Speaking of size, you

can click for bigger. Thanks for looking!

Hi Jeff,

A well accomplished set of images. It provides visual support for what you have indicated in your discussion section.

The telescope that you used is well matched with the Canon 5D.  I have several of these smaller compound mirror systems, as I use them with different cameras for various types of observations at my observatory. Since these tube assemblies are light weight and compact in size, they also make fine  telescopes for tracking on subjects that require an independent guider .

Best Regards, Mike

Jeff,

Nicely done!  The difference in libration suggests the possibility of making a stereo pair.

Nice images! 

It has turned a bit from bottom to top, eh? Reflects the seasons on Earth?

Now that's really interesting. Yes, there seems to be a slight difference in tilt almost from bottom right to upper left. How did you figure out how to show the relative size difference?  Just what showed up on the sensor? did you use exactly the same imaging conditions? Nice clear resolution as well.

Thanks for the comments, everybody!

Gregory & Verena, although both images (apogee and perigee) were reduced in size to fit the PN upload limitations, the whole image was created using 100% crops of each image so their relative size would remain the same.  I cropped each RAW image using a square that would easily encompass the larger of the two Lunar spheres (2400x2400, in this case).  I then assembled those images on a 4800x2400 canvas and flattened the layers.  Then I reduced the overall size to 1280x640, or about 25% of its original size.

There does appear to be some rotation, or it could be a seasonal anomaly?  Both images were taken from the same place and with the Moon at approximately the same altitude (about 40º above the local horizon).  There were vast differences in ambient temperature between the two shots.  The apogee shot should have been much sharper due to cooler (in California, we call it "cold") temperatures and better atmospheric stability but there were some hazy clouds that offset any advantages the cooler, more stable atmosphere might have offered.

Mike, your expertise and thoughts are always appreciated.  I've not gotten to the point where I am competent enough to align either of my mounts accurately enough to do anything more than a few seconds of exposure at higher magnifications.  For these shots, I pulled the ETX off the fork mount and put it on my tripod so, no tracking.  The perigee was shot at 1/250, ISO 400, apogee was shot at 1/100 ISO 100.