Friday, July 4, 2014

Astrophotography Again

The curse of the big telescope rebuild has apparently worn off.  We had a pretty clear night, and I was able to take some pictures.  Keep in mind that I still don't have an equatorial tracking platform for Big Bertha yet, so I am limited to very short exposures.  Complicating matters, the wind started to whip up part way through the evening so even short exposures were not doing well.  This was prime focus, ISO 100, 1/60th of second (with a bit of processing through GIMP 2):

These were taken using eyepiece projection with an 18mm orthoscopic eyepiece at ISO 1600, 1/60th of a second:

I tried some more photographs with 9mm eyepiece projection, but by then the wind was gusting enough that even 1/60th of second wouldn't do the job, and besides, that takes a lot longer than 1/60th of a second with that much magnification.

By the time Saturn was clearly visible, the wind situation had become quite a bit more difficult.  At prime focus, Saturn is tiny.  This was 1/350th second, ISO 1600, and tightly cropped to get anything at all.  It really doesn't do justice to how it looks through the eyepiece:

Here it is with 18mm eyepiece projection, 1/30th of a second, ISO 1600, not quite as tightly cropped:

I probably needed more like 1/60th exposure to get details, instead of a blur.


Jim Dunmyer said...

In the 3rd picture, there's a sizable crater at about the 7:00 position, not quite half-way between the center and edge of the frame. Just for reference, do you have any idea how big that thing is, in "miles across"?

Clayton Cramer said...

I'm guessing that the overall picture is about 250 miles from top to bottom.