lens to lens distance is not 2f in "4f system"

Dear,
I studied 4f system and I've got a question.
As far as I know, 4f system is optical filtering system (attached file).

In the configuration in the attached file, region between L1~L2 is infinity optics(ray components from P1 is parallel with each other) so that distance between L1~L2 shouldn't affect the image at P3 as far as the distance between L1~P2 is 'f', in my guess.

Am I correct? Is there any difference between "1), 2)" below?

1) P1~L1=f, L1~P2=f, P2~L2=f, L2~P3=f (standard 4f system)
2) P1~L1=f, L1~P2=f, P2~L2=not f, L2~P3=f

Thank you in advance.

Sungsik.

Attached Images

108201_1_4.jpg (38.7 KB)