Method of setting bit cell length for magnetic recording of data in a

Abstract

A method of setting recorded data bit cell length on an APS film magnetic layer in a camera of the type having apparatus for normally setting bit cell length as a function of measured film transport velocity. The method comprises detecting the occurrence of an invalid film velocity measurement and substituting a default data recording frequency that results in a recorded bit cell length on the film which ensures that a maximum number of intended data bits are recorded in a given available length of data track which might otherwise not result if the invalid film velocity measurement were used to set the recorded bit cell length. Determination of invalid velocity measurement can be made by sensing mis-positioned film in the film gate at the start of film advance, for example by detecting alignment of a perf used for velocity measurement with the velocity determining optical sensor or by detecting a delay time between start of film advance and velocity perf detection that is less than a minimum threshold delay amount associated with normal film position. Alternatively, actual film velocity may be measured and a default bit cell length set when the measured velocity is outside a range of measured velocities associated with normal film advance operation.