query_tiff is working rather slow with my big files. Maybe my files are indeed too big, ~10k frames. Even query_tiff(filename,image_index=0) would take several minutes. On the other hand, I found read_tiff works quite differently in term of speed. If I have this big tiff stack here and want IDL to know the number of frames, is there any fast way? Do I need to know something deep about the tiff file format, head codes or the like? thanks