How are you determining your ISO 160 frame or sheet is the correct "Zone I" exposure? I suspect you may have made an error in math when making or recording or reading your negative.
How are you determining your ISO 160 frame or sheet is the correct "Zone I" exposure? I suspect you may have made an error in math when making or recording or reading your negative.
I left the notebook where I took my notes at home. I'll post my results tonight, when I get home.
--Mario
--Mario
Here are the results of my test:
Ilford Delta 100 + Ilfotec DD-X
68F
12 minutes, intermittent agitation
Source: The Negative by Ansel Adams
Zone V: f5.6 1/60
ASA f Shutter Density No Density 1. No exposure (blank) -- -- -- 0.17 -- 2. Zone I 100 22 1/60 0.37 0.20 3. 1/3 stop less than #2 125 22 1/3 1/60 0.31 0.14 4. 2/3 stop less than #2 160 22 2/3 1/60 0.26 0.09 5. Zone 0 200 32 1/60 0.22 0.05 6. 1/3 stop more than #2 80 16 2/3 1/60 0.40 0.23 7. 2/3 stop more 64 16 1/3 1/60 0.48 0.31 8. Zone II 50 16 1/60 0.57 0.40
--Mario
I sure don't understand that chart.
The negative density drives the zone correlation, not the other way around.
The chart should be in order by negative density, not bouncing around.
In this case, line 4 should be labeled Zone I, not line 2.
- Leigh
If you believe you can, or you believe you can't... you're right.
1. place a black card in shade
2. meter it
3. close down 4 stops (zone 1)
4. focus at infinity
5. make the exposure
6. develop normally
7. read the negative on the densitometer
8. note where the reading is in relation to film base plus fog
9. If not .10 above interpolate by 1/3 stops (remembering that .30 on densitometer equals 1 stop - exposure is recorded in terms logarithms and the log of 2 is .30)
Hi Leigh,
The graph makes sense with Ansel Adam's book in hand. Negatives are exposed as if metered at rated speed, and that reading placed on Zone I. The remaining rows have test exposures relative to that Zone I at Box Speed shot. It's an arbitrary test sequence, not organized sequentially. Mario found a negative which meets the 0.10 over B+F criterion at an exposure 2/3 stop less than Zone I placement at Box Speed, which makes the test result indicate rated speed 160.
I think Mario's development is correct. But I would say the variables of the camera/lens/meter/shutter/flare which are also included in Mario's test (because of the nature of Ansel Adams' instructions) amounts to nearly +2/3 stop.
Mario, I'd be very cautious before choosing EI 160 for a 100-speed film.
Here are my test results with 100TMAX and D-76. I only achieve a 160 speed when I develop in stock D-76 undiluted for 24 minutes, and I barely hit 200 in 48 minutes.
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