I'll be going to Oregon to view the solar eclipse in August. Initially I was planning on taking 5D Mark III with 100-400L II and 1.4 & 2.0 III Extenders, G3X and G1X (IR Modified). I will need to take 3 tripods and will use a gimbal with the 5DIII and ball heads with the others. Naturally I want to take pictures of the eclipse progression and therefore need to use a filter until the sun is fully eclipsed. I will be using the Lee Big Stopper and Little Stopper stacked together and have tried this combination on both the 5DIII and G3X with full sun and it appears to work fine. I've taken test shots of the sun to get a starting point for manual settings, but will have to refine them just before the eclipse starts. I can't see any difference between the pictures of the full sun from the 5DIII and the G3X, which is probably not surprising given there's not much detail on the full sun (both showed a few sunspots, and they looked the same). If I want to use both cameras at the same time, I will have to get another filter, which is an added expense (looking at the Marumi 16.5 stop 77mm filter @USD125 @ B&H, but there's no ratings and it's special order (noncancelable and nonreturnable) - anyone used this?) I'm now wondering whether it is even worth taking the 5DIII if there's no real image quality difference between it and the G3X for this application. However, it would mean I'd be limited to 600mm rather than 800mm, but I suspect some of the corona at full eclipse may be cut off at 800mm (I'm not sure on this). I don't know if the lack of apparent image quality difference between the two cameras would also apply to the corona when the sun is fully eclipsed. I'm driving, so it's not a big deal to pack the extra equipment, but it means exposing more equipment to loss or theft. However, I also don't want to fall into the trap of spending the entire time adjusting equipment and shooting pictures and failing to just sit back and enjoy the 2 minute (or less) spectacle of full eclipse. I'd appreciate receiving advice from those of you with experience in shooting solar eclipses. Also, I have been advised to only use live view to set up the shots and to not look through the viewfinder (even with the filters on). So far I have heeded this advice, but suspect it is an overly cautious approach. I have an angle finder and think it may be useful for this application (let's not restart the flippy screen debate here). Your thoughts?