Thanks again, dormouse. I might be traveling when this opens and this list will be invaluable!

EDIT: is it safe to assume 70mm means it's projected as film and not digital? My local theater showed Interstellar in 70mm IMAX and that same theater said from here on they're just doing "digital IMAX" whatever that means...

I am not an IMAX expert but when I was looking at someone else's IMAX website, for each movie it listed what format showings would be available for each movie. Often IMAX cinemas have multiple screens and they may show the same film in multiple formats. There may be contention for a 70mm projector (if they have one) such as Valerian and Dunkirk being released on the same weekend.

I think when it gets closer to time to buy tickets (now supposedly June 5) call your IMAX theater and ask them what formats they will show Dunkirk in, ask them how you can make sure what format you are buying tickets for, etc.

Here is a newer list I believe was found in the source code of the Dunkirk website. They will probably post it on July 5 which is when they now say IMAX tickets will go on sale.

http://imgur.com/a/G28Q8

I hope i get a chance to see it in 70mm