Normally you would use the same ASA and different

development times. In this actual tested example after seeing two of

the results a different ASA was clearly indicated. Thus demonstrating

the power of ZONE SYSTEM TESTING.

The blue ( I hope ) plot or the one with the highest density is HP5 @

400 asa developed in Rodinol diluted 1/32 for 8 minutes at 68 degrees.

The filmbase plus fog or Zone 0 is 0.25, while Zone 1 is 0.31. That

right there tells us that 400 asa is to high. How? The minimum

difference from zone 0 to zone 1 needs to be from 0.10 to 0.15

 depending upon whom you ask. Let's settle on 0.12.

Lowering the asa # causes more exposure

and the density goes up. The middle zones are right on, but, 7,8, & 9

are 10 % high. Zone 7 has a Zone 8 density. Huh???? I just discovered

the N+1 expansion ( at 400 asa ) while looking for normal !!!!.

The purple plot is the same setup @ 400 asa, but for 6 minutes .

Now Zone 1 hasn't changed ( actually 0.01 less, so development does

affect the low Zones albeit marginally ) so we still need to reduce the

asa value, but Zones 7,8,& 9 are just slightly below their theoretical

values, so 6 minutes will probably be too much time after we lower the

asa which tells our camera " this film is not as sensitive, give more

exposure " thus creating more density.

The third run in this test of HP5 and Rodinol , the yellow plot, was the

same setup as the others . And I mean the same exact agitation

However, the asa was reduced to 300 and the development time was

reduced to 5 minutes. And ........................................................

BINGO! Unbelievable, right on numbers.

Nothing ever works out this perfectly!

Extremely normal numbers!!!!

Honestly, I did not make this up.

Given the conventional thinking that Zones 1-3 should each increase

0.10 in density and that zones 4-9 or 10 should increase 0.15 and

given a film base plus fog of 0.25 then the

theoretical numbers are : and this actual test run was:

Zone 0 = 0.25                                      0.25

Zone 1 = 0.35                                      0.35

Zone 2 = 0.45                                      0.45

Zone 3 = 0.55                                      0.55

Zone 4 = 0.70                                      0.72

Zone 5 = 0.85                                      0.88

Zone 6 = 1.00                                      1.06

Zone 7 = 1.15                                      1.14

Zone 8 = 1.30                                      1.31

Zone 9 = 1.45                                      1.44