For those of you who have flown a DSLR, I'd greatly appreciate any info on the lens or lenses you have used.
I have done two flights with a DSLR so far. I am using an old canon T2i with a 10-18 Canon zoom lens set to 10mm. (The zoom is obviously useless for this application, but it is the widest lens I currently own.) I am running the camera on shutter priority mode with the shutter speed set to 1/500, on an intervalometer set to fire every ten seconds . ISO and aperture are automatic.
I'd like to try a wide prime lens, perhaps a fisheye. Canon has a fisheye that would work but $1250 is a lot to pay for a lens I may never see again. Rokinon has some lenses in the sub-$300 range that are interesting, but it is very confusing, even on their own web site, as to which models of the lens have a chip so they can electronically communicate with the camera. Otherwise it is a manual lens, which is fine for focus, but I need the camera/lens setup to be able to operate in shutter priority mode to be able to automatically control exposure. It appears some of the Rokinon lenses do have a chip in the Nikon version, and I would even consider buying a (cheap) new Nikon D3400 just so I could use a Rokinon with it, but the first review I read of the lens was from someone who bought it for their D3400, and it didn't work, in spite of the manufacturer's statement that it was compatible for electronic exposure with that camera.
I'm new on this forum, as I'm planning something similar for this summer, but I can share with you my thoughts on the camera setup.
Most of the lenses from Rokinon are manual focus, but that's just a better thing for you.
As you're using a wide ange lens, and you're taking pictures to a quiet high altitude, you have just to lock the focus on the lens to infinity, with that you can also avoid lot of problems related with 'point to shoot focus'. I'll not recommend a fisheye lens (just to let you know, rokinon has a valid option also for a fisheye, that doesn't cost 1000$), that's a personal opinion, maybe, as you're shoot with an APS-C camera, check the rokinon 10mm f2.8, I used to have it before.
Also, for the exposure setup, I suggest to lock the aperture at around f5.6-8 max, and let the iso stay below 1600 and the shutter speed below 1/320. I know you're flying at 5m/s, and everything's moving, but with a wide lens, you don't need a so fast shutter. For sure, keeping the aperture as said before, will help you with sharpness.