35mm Magnetic Film?

[tape2]

Riho postete
Hi,
I think there's no difference of sound quality because the magnetic material is still the same. The only differences are the motion speed, film width, perforation zona(s) and the basis (which probably is not made of polyester or acetate cellulose).

By the way, 17,5 mm is something new for me - never heared before. One rare format i know 9,5mm but never seen with my own eye. Why so many formats...?

Riho

1) Magnetic film was produced on AC basis and later on PE basis. The total thickness is around 100 microns, AC version was thicker than PE. Therefore the contact to the magnetic heads is worse than with "normal" tapes wich measure about 18 - 50 microns thickness, resulting in more dropouts. This a disadvantage.
2) Normally magnetic film is driven by its sprocket holes to maintain absolute sync to picture, this leads to incresed wow and flutter compared to tape driven by a pinch roller. There is an exception, the MWA MB51 and its successors were driven by a pinchrollerless capstan, but they still use a sprocket reel to measure the speed. So again, no advantage over tape.
3) The speed of magnetic film at 25 fps is 47,5 cm/s, this is an advantage for high frequency performance, but a disadvantage because of more low frequency frequency response ripple.
4) The magnetic properties of magnetic film are generally worse than tapes, there never were magnetic film versions of PEM 468, SM 911 or SM 900.

So I do not see advantages in using magnetic film compared to "normal" tape at 1/4, 1/2, 1 or 2 inch width, apart from the more "conservative" magnetic coating which might be more stable for archiving. But you could use tapes like PER 528 or the older PER 555 which proved to be very stable.

Magnetic film was produced in widths of 35 mm and 17,5 mm (split film to save cost, half the width of 35 mm) for 35 mm film, and 16 mm for 16 mm film.

tape2