What IMAX 70mm film actually is

Camera

Large-format photography normally exposes a 65mm negative.

Release print

The 70mm print added edge space that historically carried magnetic sound stripes. The format name follows the print.

35mm 4-perf Academy camera aperture

Sound-era 35mm photography intended for the Academy picture shape, with space reserved beside the image for an optical soundtrack on release prints.

Gauge: 35 mm
Perforations per frame: 4
Travel: vertical
Physical aperture: 22.00 × 16.00 mm
Physical aperture ratio: 1.38:1

The 22.00 by 16.00mm values are the SMPTE Style A camera aperture.

Their physical ratio is 1.375:1.

The standardized Academy projected aperture is smaller, 20.96 by 15.29mm, and is approximately 1.37:1.

The dimensions here must not be used as projected-aperture dimensions.

65mm 5-perf spherical camera negative for 70mm prints

Large-format spherical photography for 70mm roadshow release prints, usually projected near 2.20:1 after allowance for print edges, soundtrack, and projector aperture.

Gauge: 65 mm
Perforations per frame: 5
Travel: vertical
Physical aperture: 52.63 × 23.01 mm
Physical aperture ratio: 2.29:1

The values are the nominal 65mm camera aperture specified by ANSI/SMPTE 215 and reproduced in professional format references.

SMPTE EG 25 independently establishes a nominal maximum scan width of 52.48mm and a 23.52mm limiting height that includes tolerance, so those transfer limits must not be substituted for the nominal camera aperture.

A 70mm release print is wider than the 65mm negative.

Its projectable image is smaller and normally masked to about 2.20:1.

Ultra Panavision 65mm 5-perf camera negative

65mm photography with anamorphic optics. The classic Camera 65 and Ultra Panavision process used a 1.25:1 squeeze to produce a nominal 2.76:1 screen image from the standard 5-perf 65mm frame.

Gauge: 65 mm
Perforations per frame: 5
Travel: vertical
Physical aperture: 52.63 × 23.01 mm
Physical aperture ratio: 2.29:1

The physical camera aperture is the same as other 5-perf 65mm photography, so the aspect_ratio field remains 2.287266:1.

The wider image exists only after optical unsqueezing.

Historical Camera 65 sources specify 1.25:1 and 2.76:1, while modern Panavision material describes the revived lens set with slightly different squeeze language.

The classic process value is used here and the conflict should remain visible.

IMAX 15/65 camera negative for 15/70 presentation

Very-large-format IMAX photography. The 65mm negative runs horizontally, and release printing places the image on horizontal 70mm stock for 15/70 projection.

Gauge: 65 mm
Perforations per frame: 15
Travel: horizontal
Physical aperture: 70.41 × 51.61 mm
Physical aperture ratio: 1.36:1

SMPTE ST 417 Table 1 specifies a nominal camera aperture of 70.41 by 51.61mm for the horizontal 15-perforation 65mm negative.

Its physical ratio is about 1.3643:1, not the projected 1.43:1 ratio.

A reported 15/70 projectable print aperture is 69.60 by 48.59mm, or 1.4324:1.

The public name 'IMAX 70mm' refers to the release print.

The camera negative itself is 65mm stock, so gauge_mm is correctly 65 here.

IMAX 15/70 projectable print image

The image area exposed through the projector aperture during an IMAX 15/70 film presentation.

Gauge: 70 mm
Perforations per frame: 15
Travel: horizontal
Physical aperture: 69.60 × 48.59 mm
Physical aperture ratio: 1.43:1

Unlike the other primary diagram records, these are reported projectable-aperture dimensions, not a camera aperture.

The original cited measurements are 2.740 by 1.913 inches, converted to 69.60 by 48.59mm.

They explain the 1.43 presentation label.

This record is included so a diagram can distinguish what the camera exposes from what the projector shows, but the exact dimensions need confirmation from a directly accessible SMPTE print-aperture standard or IMAX engineering document.