On the night of Feb 04/05, 2024, under good conditions, I attempted to acquire images of the starfield in which the solar eclipse will occur on Apr 8, 2024. This was my second attempt. Things went better -- I was able to mount my camera piggyback on the 14-inch telescope -- but I wasn't able to take good images.
During the eclipse, the Sun will be located at (J2000)
RA = 01:10:32 Dec = +07:28:47
= 17.6333 = +7.4797
My goal was to use a Nikon Z6II camera together with a large Nikon 400mm f/5.6 PC Auto lens, which would yield a field of view around 3.8 x 2.5 degrees, a bit smaller than this.
In order to avoid trailing of stars due to the Earth's rotation, I figured I ought to mount the camera onto one of our telescopes, in the "piggyback" mode, and allow the telescope to track the stars during the exposures. I purchased a Losmandy dovetail plate single-axis camera mount and it worked perfectly:
After the sun set, I was able to move to the field and verify that I could see some of the brighter stars, such as eps Psc, in the camera's viewfinder. Here's one picture, a 10 second, f/5.6 exposure at ISO 800. North is up, East to the left; eps Psc is the bright star near the right edge, above center.
The problem was that I couldn't focus properly. The image above was taken with the focus ring twisted as far as it could go towards "distant objects;" in other words, the ring was moved to the infinity position. Nonetheless, stars were small disks, not points. I checked and verified that if I twisted the ring to a middle position -- turning the stars into big disks -- and then gradually twisted it toward the infinity mark, the big disks shrank gradually, but did NOT go through a point-like size and expand back into small disks. This was the closest to a point I could achieve. (There's also some chromatic aberration, clearly)
The double star in this zoomed-in section of the image is 77 Psc; its components are about 33 arcsec apart. The radius of the disk is not much smaller than that, alas.
I noted that the focus ring would not always hold its position when I released it; that made taking pictures even more impossible.
On the bright side, the dark frames I took, with the lens cap on, did yield some useful information. A 3-second dark image revealed that the great majority of pixel values (in the "g-band", after extracting the green-pixel data from the RAW images) were either 0 or 1 ADU. A histogram of the dark counts showed a small tail to larger values, with sawtooth-y pattern of period around 4-5 ADU.
I had to remove a small refractor from the dovetail plate on the 14-inch to mount the camera on it. When I tried to replace the refractor on the plate, one of the plastic "wingnut" or "thumbscrew" pieces broke. I guess it had just grown old and brittle. I ordered a set of replacements from Losmandy, both T-handle 1/4 and T-handle 3/8. I'll use them when they arrive. Fortunately, I can still mount the camera-holding unit on the dovetail.