Ah, your father has a wonderful face for photography and/or drawing, I must say. Full of character due to the wrinkles, folds, and brow. A very nice subject.
None of them really shine as any more than candid shots, but the last one would look simply stunning in black and white and with a bit of work in the darkroom / filters and the like in Photoshop to heighten the sense of contrast and varying values.
Try to localize your flash / light a little better as well, so that you bring the focal point to a stronger position.
Other than that, they look nice, but have room for improvement.
I am very, very fond of #4.
Something about it is almost...haunting. It makes me think about what he could be thinking about. Reflecting on something in his life.