Consider whether or not your script is suited to the IMAX medium. The entire process is much more costly than filming on standard mediums such as video or even 35mm, and not all films belong on IMAX screens. A character drama would perhaps play better in a smaller, more intimate theater. However, if you're looking to create an action-packed thriller or a documentary complete with aerial shots and ancient ruins, then IMAX might be the best fit.
Purchase the equipment needed to shoot a true IMAX film. This includes 70mm film and a camera capable of shooting horizontally.
Hire a cameraman experienced with this medium, as 70mm film is costly and mistakes from an inexperienced director of photography will add up quickly.
Shoot the film. Keep in mind that sweeping vistas and action sequences will take the most advantage of the medium, though detailed close-ups can be impressive in such a large format. The sheer size of IMAX screens will magnify any mistakes you make, so take extra care to light each scene carefully and to make sure the scene is just the way you want it.
Edit the film. Keep in mind that the massive that the IMAX screen may require a different editing style than with regular movies. Run tests on an IMAX-sized screen, if possible, before finishing the final edit. A cut that works on a computer might not work when enlarged thousands of times to the IMAX screen.
Take extra time on perfecting the soundtrack. IMAX theaters can typically play back six-channel digital sound through more than 40 speakers, so a crisp and perfected soundscape is critical. Though it may require a great deal of work to make a film that still sounds good on this kind of system, it can be one of the best opportunities to use sound to the advantage of your story and film.
Finish and print copies of your film. If you have a contract with the IMAX company, finding willing theaters to screen your film shouldn't be difficult.