Jim, let me tell the way I used several times to calibrate apertures, as I rescued many of my lenses from trash I ended swapping several shutters, also I upgrades several lenses by purchasing the cells alone...
1) Prepare a "wall" (indoors is possible) that has an stable and uniform illumination
2) Take a patron lens that has well calibrated apertures, mounted in the view camera focus at infinite.
3) Point (with the patron lens) to the wall you prepared, use a luxometer to measure the LUX reading in the GG plane (GG removed may be better perhaps, id the patron lens has very different focal) in all apertures , you may sustitute the GG by a clear glass for total precision in the sensor position, you may use a $20 luxometer for that:
Attachment 202088
4) Rest is easy, isn't it ? Mount the lens you want you calibrate, focus infinite, point to the approx. same point on the wall, ajust aperture to match the LUX reading in the patron lens for each aperture, and make the marks in the aperture scale.
It is a transmission based aperture, not a geometric based aperture, but the newly calibrated lens will expose like the patron lens, speed accuracy apart.
I have this one
https://www.amazon.com/-/es/2000-Cue...504212&sr=8-45
But the one having the cord for the sensor is more convenient, I got that one because it is takes 0.01 readings, which I use to calibrate film in LIRF conditions.
Another choice is mounting a (say) Nikon F-Mount extension ring on a monorail camera lensboard, place that lensboard in the rear standard and mount an SLR on it, (so you don't need to touch a DSLR
) use the camera meter readings to match the reading of the apertures of the two lenses, the patron one and the one you adjust.
You may also use a probe meter if you have one:
Attachment 202089
...but the numeric reading in the luxometer will allow a more accurate matching.
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Not necessary to tell you that the view camera has to focused at infinite which each lens to avoid the compensation factor... I point it because somebody else may use that procedure in the future...
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After doing that and calibrating shutter speeds exposures were totally perfect.
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