Don't get me wrong. Just because something has flaws doesn't mean it doesn't work. I'm just saying that the ZonetoTone testing method is practically identical to the Zone System and as such has the same misconceptions. We all know the Zone System testing can result in quality work, but that doesn't mean it's perfect and there exists some fundamental misconceptions. In a nutshell, the results you are getting might not be the results you think you are getting. Isn't better accuracy one of the points of testing?

The explanation for misconception one can be found at http://www.apug.org/forums/forum37/9...-exposure.html

The ratio between the ISO speed point and the metered exposure is 3 1/3 stops. ZS uses 4 stops. That means that the resulting values cannot be the same under identical conditions. This is the cause of the preponderance of lower film speeds by the ZS method compared to ISO speeds. Now, there's nothing wrong with the lower EIs produced by the ZS. It's basically the same as film speeds before the 1960 standard which eliminated most of a safety factor. ZS testing just puts it back in. The potential problem comes for thinking ZS testing produces the "true" film speed, or believing it has determined a more accurate rating, or attempting to comparing the results it to the ISO speeds. As they have different testing methods, this can not be done with any real meaning.

A good simplified alternative is to a) only stop down 3 1/3 stops b) just shoot at the box speed c) stop down four stops with the understand of what the results really mean.

The explanation for misconception two can be found at http://www.apug.org/forums/forum37/1...ain-sight.html

This is actually simple. While the scene being photographed might have a seven stop range, inside the camera, it will average around a 6 stop range. Flare will reduce the apparent luminance range at the film plane. Now, if you have low to no flare testing conditions (like the ZS method) and measure at seven stops, you will be measuring for a longer illuminance range than what will exist when shooting a seven stop scene and consequently the negative density range determined at the point will be too high.

Here's where it gets more complicated. You can pick an aim density range that compensates for the testing in no flare conditions. This range would be higher knowing that when shooting, flare will reduce it to where you really want it. The ZS does this accidentally. If you look at the film gradient based on the testing parameters defined by the Zone System, and the gradient defined by tone reproduction theory which incorporates flare, they are the same.

Consider the NDR for the ZS 1.25 and 1.20 for ZonetoTone's method. These values are much higher than the NDR aim for a grade 2 paper printed on a diffusion enlarger, 1.05. But as all three methods use basically the same gradient value, the resulting negative density ranges for identical scenes will to be the same. Not just will be but have to be the same according to basic physics. Considering one method factors in flare and one doesn't, and one conforms to the NDR for a grade two paper and one doesn't, there can be only one conclusion as to the real resulting density range?

With the Zone System method, you are testing the film to a density range of 1.25, but you are ending up shooting with a density range closer to 1.05 for a seven stop scene. This will print well on a grade 2 paper. So there's no need to change anything, just understand what's going on.