Couple of things-- the Alpha channel is not generally used for a bump map; bump maps reflect roughness of a surface. . .alpha corresponds to transparency. I assume that what you're trying to do is to take the alpha and create a new image, jpg or whatever, for use in the alpha channel of a 3d app like Max, right? Open the tiff in Photoshop, go to the layers, copy the alpha layer, then create a new greyscale file and paste the alpha there. . .now you have a file which is the alpha from your original Tiff. But again, this is generally not what you want for a bump map.