16 bit TIFF & .PSD convertion to 16 or 32 bit BMP

I am unable to convert/"save as" a 16 bit TIFF or .psd file to 16 bit BMP. The only way I am able to do it is to first convert the TIFF or PSD to an 8 bit file.

Once a TIFF or PSD is 8 bit you can "save as" a(n) 8/16/32 bit BMP. Is there a workaround? Obviously if I want a 16 bit BMP I do not want to throw out all that data in my file, by going to 8 bit first and then back to 16/32 bit.

That's because a 16-bit TIFF files measn you have 16 bits per channel for a total of 48 bit (in RGB with no Alpha channels)

A 16-bit BMP has a grand total of 16 bits (IIRC, 4 bits per channel, plus 4 bits for an image mask) and a 32-bit BMP a grand total of 32-bits (again, IIRC, 8 bits per channel plus 8 bbits for an image mask).