Hmm, okay, this is all very interesting, thanks! I’ve had macro lenses for years, but my experience is just in real-world flora and fauna, not these ultra-controlled conditions. I seem to have gone down this as-close-to-perfection-as-possible rabbit hole, but I want to be sure I’m capturing the best scans I can, so I have really been experimenting and scrutinizing the results. It would be a shame to have my settings off just a little and discover I could have done better with just a tweak here and there.
I found that my lens was sharpest at f6.3 under regular conditions. For some reason, I was thinking I needed to change my aperture to accommodate the polarizing filters, but now I see that it makes more sense to leave the aperture where it is and compensate with shutter speed. I do use a remote shutter release and a delayed shutter, but I could always make my stand a bit sturdier.
The results I get using cross-polarization are fantastic, not just for silvering but also for those pesky textured prints, so I’m really glad to hear that this might be an easy fix. Thanks for the guidance! I’m looking forward to re-scanning this album and comparing the results.