I had given another answer:
I am whole but incomplete,
A camera is whole if no parts are missing, no doubts. But also, a campera is incomplete without the photograph, because it cannot act by itself.
I have no eyes, yet I see.
A camera can "see" with its photosensor but it has no eyes.
You can see, and see right through me.
If you use your camera, you look "through" it to get the perspective. That's not my subject and I cannot name it, but classic cameras have these monocular-like windows to look through. (If one could write the term as a comment, thanks.)
My largest part is one fourth of what I once was.
The largest part is the case, cameras have been very large in the past.