When is 50mm NOT 50mm?

Let me just lay out the scenario to see if we're on the same page:

My tripod is setup.  I shoot a scene with an APS-C camera and a 50mm lens focused to 20' at f/1.8.

I take the camera off the tripod and put a FF body on with a 75mm lens also focused to 20' but at f/2.8 to have the same DOF.

I have the same FOV, same "composition", same perspective, same depth of field.

Maybe the discussion went off track because we're not comparing apples to apples ?

- Dennis

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