These were taken on a Gitzo tripod with an Arca Swiss head mounted to the lens tripod foot. To expedite swapping filters, no hood was used. Mirror lockup and a timer were used along with no possible movement in the area to ensure the sharpest shot possible. Focus was set once for the baseline shot and never adjusted for the remainder of the testing. In theory the depth of the various filters could have some impact on sharpness, but I avoided refocusing per filter to keep things as consistent as possible.
I shot in Manual mode and manually dialed in the shutter speed to the indicated 0 EV exposure for the MIN shot and 25 seconds for the MAX shot.
For the B+W & Bower, I rotated until they locked on the MIN and MAX points. For the others, I aligned them manually to the MIN and MAX points.
The testing was done at night to avoid any outside light influence, and the lighting was consistent the entire time of the shooting. If you’ve read my blog reviews before you know my bookshelf well, so I’ve done the same basic testing but significantly more carefully to insure the best results possible.