Making Sense of Jupiter’s Problems

Starlog Late Evenings of August 19th through 22nd, 2021

My sessions on Jupiter’s opposition night did not go as well as I had desired.  After imaging what I consider to be my best Jupiter ever a few weeks prior, I had a lot of hope for this night.  It was relatively clear, though not as clear as Saturn’s opposition.

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See the first image in this post?  You should notice two issues with it.  First, Jupiter is a tad blurry.  Second, the Galilean moon is shown as double.  Both may be due to the same out-of-focus issue, or so I first thought.

I remember seeing all the Jupiter videos as they were being shot, from my DSLR camera’s LCD screen.  Through practice, I have gotten pretty good at guessing the final quality, based on the real-time LCD image.

But this night’s issues were a mystery.  What went wrong?

I decided to retry on the next available night, which happened to be a couple of nights later on August 21st.  Here is the best final image from that session:

I did a lot of post-processing to clean this image up, but it is still a tad blurry.  And more importantly, this time I noticed, on the live LCD screen, that I could see Jupiter’s moons as double, like in the first image.  I kept trying to “fix” the double moons, but no matter how much I refocused, the double-ness remained.

So I tried again on the following night, August 22nd.  It was partly cloudy and not ideal for telescope imagining.  Still, I wanted to try troubleshooting, like playing with the order of my Barlow and filter.  I also cleaned all my optics.

When I started the August 22nd session, clouds were on and off, and I only got in a few video sets before Jupiter was completely covered. But I could see to the West that clearer skies were rolling in.  It was going to be a patchwork of opportunities, and I knew my next window would be in about 20 minutes.

(It should be noted here that the early Waning Moon was out and well to the East of Jupiter, illuminating the sky and playing tricks with cloud cover.  This added a little complexity to guessing when the area around Jupiter would be clear.)

And so I went inside for a while, taking my camera.  Sitting in my living room chair, I began to fiddle with the camera’s settings, and the thought occurred to me…maybe a setting is off?  I immediately noticed that “image stabilization” was set to ON.  It was the highlighted setting.  Did I accidentally bump that setting between Jupiter’s opposition night and now?  As a general rule, any image stabilization should be OFF for astrophotography.  IS is to make a stable frame when you are videoing your kid blowing out his birthday candles, not for recording pictures of Solar System objects hundreds of millions of mile away.

Yes, I turned IS off at this point, and tried videoing Jupiter again, once the clouds broke.  Visibility was not great, but sufficient.  I did observe that I could still see Jupiter’s moons as double on the LCD.  So did IS make a difference, or is that just a video screen artifact?  I still do not know.

It may be difficult to tell after post-processing, but I do feel turning IS off on the very last sessions made a difference.  Below is the best late result from that evening.  It is not up to my prior Jupiter, but enough to convince me to ensure image stabilization is OFF from now on for the planets.