Full Frame Focus

We're getting close now to the big event - the April 8th Total Solar Eclipse! And as the days fly by I'm trying to finalize my strategy for getting some memorable shots while balancing my desire to also "be in the moment" during the 4+ minutes that are going to whip by in time-warp fashion.

For the 2017 eclipse I used our "family" camera - a Canon t6i - attached to my Vixen 600mm refractor. That particular model has an APC (or cropped) sensor, which has the effect of increasing the focal length. Per Fred Espenak ("Mr. Eclipse"), a cropped sensor will increase the size of the Sun in your photo by about 50%. And while I was blessed to get some very nice shots using it at the 2017 eclipse, I felt that I wanted to have a bit more space around the Sun to better capture the full extent of the corona. While the 300mm telephoto lens on the t6i would certainly do that (and worked well for the Albuquerque Annular eclipse), I like the sharp optics and higher focal length of the Vixen.

And so began my research into getting a "full frame" camera body. There are basically two options now - a standard DSLR that has a flip-mirror in the optical path, or a "mirrorless" design where the sensor feeds directly to the screen on the camera rather than looking through a view finder. The latter is still fairly expensive (IMO anyway) at over $1,300 for a decent quality unit. 

But with users switching over to the mirrorless format, I reasoned that their old cameras might be popping up on eBay. After an afternoon of evaluating the offerings I found a Canon 5D Mark II camera body for $350. Sold!

A few days later the camera arrived. The body cosmetically looked acceptable, so the next step was to charge the battery to verify it turns on and works. That test passed, but then the challenges of getting it eclipse-ready started. The first disconnect was the SD card I ordered did not fit - these older units take a much larger UDMA card. Fortunately I could find one with adequate capacity and good transfer rate.

With the camera charged and outfitted with a card I turned my attention to hooking it up to the Vixen to see if I could get some Sun pictures. While my existing T-ring that I use to hook up my Canon t6i fit the Mark II, I immediately realized that since it was a 1¼ inch design I was shooting myself in the foot by not having a 2" T-ring. A little internet searching turned up a great company, Telescope Adapters, that had just what I needed. A couple days later I had my adapter and was ready to target first Solar light for the full frame camera. On the 9th of this month that took place, and I was pretty impressed with the wider field.

The final hurdle was to integrate the camera with laptop software to automatically take a sequence of shots during the eclipse. In 2017 I had tried Eclipse Orchestrator but did not feel confident enough to let it run the session, and ended up manually taking shots via the Canon app on my tablet. That definitely impacted my ability to "be in the moment" for the eclipse (but it was still a riveting, surreal experience!) Additional research turned up the Solar Eclipse Timer and Camera Controller (SETnC) application. This seems a little simpler and hopefully will prove to instill greater confidence in turning the camera control over to it.

Last weekend I set the Vixen up again and played with the SETnC taking exposures. While setting up an exposure sequence and executing it went well, I did find that the best rate for snapping off shots is roughly 1 per second, even with the premium UDMA card. That is a bit of a disappointment as I was hoping to be able to click off at least 2 shots per second to provide some bracketing during the C2 and C3 events  (e.g., trying to capture Bailey's Beads or Diamond Ring). Given the age of the camera it is really not a surprise, but at this point I think I am going to let fate dictate the outcome and hope for some great souvenirs of my last Total Solar Eclipse. After all, luck is always a factor in any such endeavor (just ask someone who's been clouded out for their celestial event!)

Image of naked-eye sunspot AR3590
with Mark II and Vixen 80mm