This is neither speculation nor pontification on my behalf, Sal. ULF shooters went crazy sticking little tabs of putty or ATG tape on holders to try and prevent sag. Serious concerns like Sinar tried to reinvent the filmholder. Until that problem is solved, how can anyone trust your casual method of testing, or that of anyone else who just wings it. And even your opinion about various lenses differs from that of many others who use these same lenses. It's a crap shoot unless you interject some controlled objective methodology to it. No, not all lenses are equal at f/64. And probably no lens at f/64 is going to be equal to the very same lens at f/45 unless depth of field is itself the priority. But by definition, this forum is concerned with the behavior of sheet film under such circumstances. Bringing 35mm lenses into the discussion doesn't do anything to solve that - and please, Fishbulb, don't tell me something I haven't already known for decades. I'm not about to test some stupid Sigma lens with respect to 8x10 shooting.