Can I save my iphotos directly onto My Passport Essential SE on my MAC?

I have just purchased the My Passport Essential SE 1TB to purely save my photos onto it and clear a space on my macbook pro.  Is this possible because I just seem to have the option of only backing up the whole of my computer.  I have read the instructions, and can’t find information on this - so please can anyone help?  Thanks!

You can manually transfer your pictures unto the external drive and change the setting on Iphoto to read the pictures directly from the external drive. 

Is not recommended to have the pictures in only one place since that way you are not protected in the event of drive failure.

If you just want to auto backup pictures only, the software that comes with the drive allow you to only select picture as the category to back up.