The sensor on my Olympus DSLR is in the 4:3 aspect ratio. This is one thing that sets it apart from the more common APS-C DSLRs. It's just one difference but I thought I'd mention it.
I do a lot of airplane photography. I find that the 4:3 frame usually leaves too much space at the top and bottom of the frame. So, when I post those pictures online, I often crop them to 3:2 (matching the 4x6" pint size) because it is more suited to the long, slender aircraft body.
One the other hand, I also do a lot of car shows. I find the 4:3 frame is extremely well suited to photographing cars from the 3/4 front position...the common "beauty shot" angle. Therefore, my auto pictures are generally posted using the full frame.
Back in the old days, I did most of my own darkroom work. I still have a couple of enlargers assembled in my basement. I doubt if I ever printed more than a handful of photos at the full frame in it's original aspect ratio. It's not that I purposely made a decision to crop all of my photos; it's just the reality that my various cameras produced different sized negatives and none of them perfectly matched available photo paper.
If I HAD to print a full frame, I could do so but I would then have to trim the photo paper.
This is one of the nice things about digital photography. It's much easier to match aspect ratios and subject matter when you can do your own post processing in the computer.
