Eclipse 2024 Preparation

Final setup and tests for Monday’s totality from Jackson, MO. I’m fortunate enough to have family living pretty much on the centerline for this one. Depending on which eclipse map web site I visit, the centerline either goes by about 50 meters west or 50 meters east of my location. This is a 1200×1200 crop from a 6000×4000 frame; this was taken from the JPEG preview, not the raw data, and had a mild unsharp mask applied. If I can get this good of a focus on eclipse day, I’ll be happy.

This is the same image as above, but a 200% zoom of the upper right quadrant. North is right in both images

I was already certain I had everything in place but needed a clear day to take some images and confirm my plan’s selection for exposures. Good thing I did as I had expected to need about 1/2000 sec at ISO 200, but that was overexposed. The histograms are tricky to interpret when you’re trying to stare at a washed out screen (inside a laptop “tent” to help) as the sun itself is only a small part of the image, so the histogram is dominated by a huge spike near zero.

In any event, I got fooled by the preview images and the automatic scaling which never work the way I expect. Backyard EOS does not seem to to show me a raw histogram which is annoying. The raw images I took from the RedCat 51 (250mm FL, f/5) are severely underexposed at my ISO 100 1/4000 sec exposure with a max intensity of about 0.075. The ISO 200, 1/2000 sec show a max of about 0.18, and the ISO 200 1/1000 sec show a max of about 0.24. So I can easily go to ISO 400 and 1/1000 sec or maybe even 1/640 sec. for the fastest. I’ll want to show a few longer to get partial phases when haze/clouds pass through, even knowing I’ll probably be throwing most of those away.

The obvious thing I can’t test is the exposures during totality. For those, I just have to go with Mr. Eclipse.