Setting Exposure Compensation Using Filters

<p>I am using an 81A Filter on my lens attached to a 35mm film camera (Nikon F5). My question concerning how to set exposure compensation is as follows. With the Hoya 81A filter attached do I set my exposure compensation +1/3 stop or -1/3 stop? I will be using 35mm color negative film listed as iso-100. I have read and observed charts which specify how much I need to compensate, but they never really state if the compensation is to be set as + or -</p>

<p>For a camera metering through the lens TTL no compensation should be needed at all. If you use a flash in auto mode you have to compensate + since the flash sensor does not "know" about the filter.</p>

<p>If the filter is darker than nothing, as it use to be, the compensation should be set to a positive ammount... this way you`ll be <em>adding</em> a little more exposure. Think that the filter is something that blocks some of the light... hence the sensor/film will receive a lower ammount of light. You need to <em>increase</em> the exposure in order to reach the correct level.<br /> I suspect this is the reason because they never specify if it is "+" or "-" (it is always "+").</p>

<p>And at the opposite, if the compensation is aimed to give a lesser exposure, then you have to set the wheel to minus ("-"). It could happen, e.g., when the camera meter is used on darker than medium gray surfaces and you want an incident-like reading (darker images).</p>

<p>As Markus says, if the camera is metering via TTL (Through The Lens), no compensation use to be needed. We could say the filter is then "considered as a part of the lens".<br /> Don`t forget that the ISO on the box could be different depending on the color temperature of the light source.</p>

<p>Leo, why are you even bothering to use an 81A filter with colour negative film? The effect of the filter is so slight (a less than 20 mired shift) that it can easily be emulated or compensated for in the printing process. A full CT filter like an 85 or 80A is a different matter, and is outside the correction range of negative film, but not so the pale amber of an 81A.</p>

<p>In any case, as has already been said, the TTL exposure metering of your F5 will automatically compensate for the filter factor.</p>