I have been successfully exporting targa sequences with embedded Alpha's from FCP using QT conversion. However, the compression that is automatically put on this, (which is probably RLE or LZW?) is creating individual targas with different file sizes, ie, 128kb, 72kb etc etc.
When exporting from AE you have the option to turn off the RLE compression which results in consistent file sizes, (about 1.6mb for D1 Pal frames). Does anybody know if it is possible to turn the compression off when exporting from FCP?