I was just wondering about the correct method when using pre-exposure of film for increased shadow densities that involve exposures that require reciprocity compensation. In particular when the overall exposure time must be increased due to reciprocity but the ZoneII pre-exposure falls outside of the parameters requiring film reciprocity compensation. For example let's say I am shooting 100ASA film and get a reading of 9 on my Pentax Spotmeter and wish to use f45 for my exposure. At f45 the exposure time is 4 seconds and a compensation for reciprocity must be made. However, if I wish to employ a pre-exposure at ZoneII the indicated exposure time read from the meter is ½ second, this is outside the parameters of the films reciprocity. My question: Will the ½ second pre-exposure be sufficient to bring the increased shadow density or must this be increased by a factor due to the increased overall exposure that will be required because of the reciprocity effect? Thanks!