So, I've been following this thread with some interest, and this raises an interesting if not entirely related question. For an infinity-corrected objective, my understanding is that the exit rays from the objective are parallel, in which case, the space between objective and tube lens is arbitrary ("infinity space" as you put it). But then, why is it that there are recommendations for this spacing for particular implementations; e.g., Mitutoyo objectives and Raynox tube lenses? Is it because the actual focal length of the tube lens is not exactly 200 mm? I'm trying to wrap my head around the optics and this is one of the sticking points in my mind.rjlittlefield wrote: I meant #1, with the polarizer in infinity space, but as far from the objective as possible.
For what it's worth, I do understand that the spacing between tube lens and sensor is related to the actual focal length of the lens, and that reversing the lens does not necessarily maintain this spacing (due to telephoto ratio). But I could swear I've seen recommendations for the spacing between objective and tube lens.