*THIS IS THE CORRECT PLACEMENT OF MY EARLIER MISSPLACED THREAD* I have little experience using filters in my photography; the times that I have tried to use them I've been less than pleased with the results. I shoot mainly black and white and so Ive only ever used an orange or red filter. I do know that using any filter other that a UV/Haze filter will require that a filter factor be computed into the exposure, but that in the case of a TTL meter on an SLR the filter factor is already computed because the light entering the lens and being metered first has pass through the filter. Ive also read that in cases when a heavy ND filter or a dark red filter are used the TTL system can be thrown off, resulting in an erroneous meter reading. Well here is my problem: I shoot with a Canon New F-1 (mid to late 80s center weighted meter screen) and also a Nikon N80 (bought 2005 with spot, center weighted and 3D matrix meter) and as far as I can tell neither cameras TTL meter compensates for a filter being placed on the lens. I have taken readings of a scene with both cameras recorded the meter reading and then placed my orange (G) filter or my red (A) filter on the lens and with both camera using either filter there was no change at all in the meter readings (there was a slight change with the red filter, but no more than 1/3 stop). I have looked up using filters in my basic photo how-to books and tried to find information on filters and metering in the Nikon N80 manual and have had no luck with either approach. I totally assume that the problem is all of my own making; that there is something that I am missing, so please fill me in on where I am going wrong. Thank you for any help.