Talk about beating a dead horse. The guy can EASILY get to a slow shutter speed (assuming that is what he wants) using the film he has with a couple of the filters he already has -- and without having the stand on his head and spit nickels. I know that, and you know that. Now he knows it, as well.
At /22 good, modern 4x5 lenses are diffraction limited. If this is important or not... this will depend on what one wants, and if it's better or not to stop beyond /22 because DOF vs sharpness is a technical matter. Bullsh*t is manure, so not a photography term.
A still unsolved problem for me is when using heavy ND filters, that stray strong internal reflections could happen at some camera/light angles, (that were not light leaks, lens well shaded) somehow light bouncing in the optics or camera... You might see this if a bright light (like the sunset, very bright lights/reflections/beach sunshine/desert) on or slightly off lens axis... Usually a broad flare covering much of the neg...
Stacking filters is out for heavy ND's...
Steve K
Stacking filters has a variable effect, it depends on:
> Fiter quality, Hoya HD3 have less troubles than inferior Hoyas.
> Scene, sun in the framming is not the same than a subject in the shadow.
> Focal, sun in the scene delivers more relative parasite light with a long focal than with a wide.
> Clean filters vs not perfectly clean ones.
A polarizer in the stack is very good if sun is in the framming. As direct sunlight comes strongly polarized the Pol will remove a big share of it, reducing parasite light to a fraction. I guess placing the pol in the outer side of the stack may be the best, as direct sunlight is reduced from the begining of the bouncing chain.
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