I know you want to see the latest blockbuster in IMAX 70mm on opening night, but if you want the absolute best presentation you should wait 7-8 days after it comes out to see it. Why? Because IMAX 70mm film is dirtiest when it’s new. It takes about 30 screenings before the print is fully cleaned and once it’s clean it stays clean.
Why is this?
Prints arriving from the lab are fairly clean, but they can pick up dust on the edges of the film in shipping. After that the print needs to be assembled on a platter. During buildup a print generates static (especially during the low humidity & winter) and it attracts dust. Dust in the air can also settle on the print even if humidity is higher.
Before the film gets to the lens it passes over particle transfer rollers which are kinda sticky. These rollers pick up dust and any foreign matter stuck to the film. These rollers are also the only roller that actually touches the frame image. A piece of dust will eventually end up on the field flattener and it will stay on the screen until it’s wiped away (which doesn’t always work). If you see a speck of dust that is in sharp focus and doesn’t leave the frame it’s because it’s stuck to the field flattener lens and hasn’t been wiped away yet.
By the way, the audience never sees the wipe. It’s a really ingenious design.
Typically new movies premier Thursday evening and are shown twice, after that depending on runtime and turnaround they will typically be screened 4-5 times a day. Oppenheimer was screened twice before opening to the public, 1 tech screening and 1 promo screening. After that we had 2 showings on Thursday and then 4 a day after that. It took just over a week to get 30 passes, after that the print was flawless.
I was invited to screen Dunkirk with Christopher Nolan in IMAX 70mm a few weeks before the world premier. That print was so dirty. I felt terrible for Nolan, but I doubt he knew. Every director I’ve interfaced with never stays to watch their movie in these type of screenings.
It looked amazing, but it just had so much dust that needed to be wiped away. With so many flying scenes it was easier to notice on a bright sky.
I’ve seen 20+ year old prints that look brand new with no dust or dirt on the screen. If an IMAX 70mm print is cleaned and doesn’t get damaged it will last probably 100 years and still look flawless the whole time.